Outstanding and comprehensive videos (this one and for EGR and VSV troubleshooting)!! I change the valve cover gasket, on my wife's 1998 Rav4, and soon afterwards it sounded like the valves were clacking while the engine was loaded at 2G just before automatic transmission made a shift up in gear. Originally thought and feared I would have to remove valve cover again to perhaps adjust valves. After 3+ months, a P0401 code came out. Thanks to your videos I have a gameplan to troubleshoot my EGR components! Thank You!!
Seriously though. These are amazing videos. So clear and concise and well explained. And the video and audio quality are awesome. I would pay money for these for real. Wheres your Patreon? 🤩
You're the BEST Instructional Toyota Mechanic on UA-cam! I've learned so much, and with your help, fixed all kinds of problems on all of our family cars...saving all of us big bucks! With your HELP, I can usually do the diagnostics, buy the right tools and parts, and get the problem fixed RIGHT the FIRST TIME! Please keep up the GOOD WORK!!
I am at owe with everything in this video… the level of detail, structuring, information…the editing, description….it is all above and beyond. Thank you so much for the effort. I’m trying to fix my sister’s 97 RAV4 and this is exactly what I needed. Again, thank you for this educational video! I learnt so much!
Great job making your videos! In my case my 2000 RAV4 failed the vacuum to EGR valve test due to a completely clogged port on the intake manifold where the egr bolts to the manifold. Cleaned the port and all is good! Thanks! You rock!
Very thorough walk through of the EGR system that allowed me to diagnose the source of my P0401 OBD code: the EGR valve had blocked up with carbon deposits over the course of 240K miles so it failed Test 1 in the video. I cleaned the EGR valve and manifold port with carburetor cleaner, reinstalled it, and the OBD status is OK. Great video
This is the most comprehensive video regarding EGR. I don’t own a RAV4, but I do own land cruiser from that period. Therefore, the component is identical. Thanks for the Awesome course.
It's been awhile since you posted this video yet timely and informational like being in a mechanics seminar,,, thanx for presentation on the EGR Circuit.😊😊
I have an '89 Toyota pickup and found that your detailed component tests for individual EGR components could be reused to test the components in my truck without difficulty. Thank you! Your bench tests are fantastic and go above and beyond the FSM - was able to diagnose my problem in 10 mins after fully digesting your video. Happy New Year! I should add that you taking the time to make careful indices/a table of contents is just astoundingly useful for going back and refreshing specific procedures after the fact.
Wow, that's so great - excellent diagnosis on your pickup! I'm so glad the video helped, and I'm glad you like the timestamps (I like to jump around while watching videos, too, which is why I like to include timestamps) Happy New Year to you, too and thanks for watching! : )
As always L35, super instructive video. My RAV EGR issue back 2008 turned out to be the VSV with the in-engine vacuum test. Interesting, but the hose to the MAP you mention developed a small crack leak and caused an idle issue a few years ago.
Love your calm, clear and assured demeaner. The videos are well lit and the post production graphics help a lot! Thank you very much and keep up the good work!
Thank you! This video helped with a P0402 issue on my 1999 Tacoma. The VSV was bad. Your detailed explanations in this video helped me troubleshoot my issue
@@L35inColorado i am planning on replacing some vacuum hoses for the egr. Would you happen to have a link for the specs? Thank you. (Will replacing it with silicone type be good?)
Always looking forward to your excellent instructional videos. You go above and beyond. I still have my 99 toyota rav 4door running great. 245,000 miles. Muchas gracias paz stay safe
My vacuuum modulator diaphragm went bad causing P0401. One junkyard trip and $14 later, problem fixed with a replacment from a junk rav. Who knows how long that will last but i got a spare VSV, vacuum hose set, and EGR oem valve too just in case. Wow, the vsv is so easy to get to on front wheel drive models. Was able to stick a long extension up to the 12mm vsv bolt and unbolt in 10 seconds. Very different experience from my AWD manual Rav... Thank u for the great video
Thanks for 1,200 Subscribers! Links for the EGR Valve and VSV replacement videos are below the Timestamps: EGR Components Detailed Explanation: 00:01:10 What is EGR (Exhaust Gas Recirculation) 00:01:50 Path of Exhaust Gas from Exhaust Manifold to Intake 00:02:27 EGR Valve location and begin explanation 00:02:28 EGR Pipe location 00:03:08 EGR Valve in hand 00:04:15 EGR pintle when under vacuum 00:06:17 Connection between EGR Valve and Vacuum Modulator 00:06:35 The two "sides" of the EGR circuit (vacuum side and exhaust side) 00:07:13 VSV, Vacuum Switching Valve explanation 00:08:59 VSV with shorter hoses for demonstration 00:11:18 VSV under vacuum, not energized 00:12:37 VSV hooked up to 12v battery for demonstration 00:15:41 Vacuum Modulator explanation 00:16:52 Vacuum Modulator in hand 00:17:43 How to remove Vacuum Modulator 00:18:10 Opening the top of the Vacuum Modulator 00:19:18 Explanation of Q, R, and P ports of Vacuum Modulator 00:22:37 Vacuum sources at Throttle Body 00:23:40 Holes for Ports E and R 00:27:59 Role of ECU (engine computer) in EGR circuit 00:28:49 Role of MAP (Manifold Absolute Pressure) sensor in EGR Circuit Begin Engine Tests: 00:30:44 Begin In-Engine Tests 00:30:51 Check all vacuum hoses for leaks 00:32:18 Check for vacuum at Throttle Body 00:35:04 Test 1: Check EGR Valve directly to see if it opens 00:39:50 Test 2: Check VSV function with Key OFF and Key ON conditions 00:46:10 Test 3: Check Vacuum Modulator for flow 00:47:59 Test 4: Check Vacuum Modulator for diaphragm response to backpressure 00:50:09 Prepare hose tees and gauges for next tests 00:51:36 Test 5: Check vacuum at Q port 00:59:17 Test 6: Check vacuum at EGR valve with engine cold Warm up engine before Test 7: 01:01:10 Test 7: Check vacuum at EGR valve with engine warm 01:04:14 Test 8: Check vacuum at Q with full manifold vacuum on P Bench Tests: 01:11:20 Bench test EGR Valve 01:13:27 Bench test Vacuum Modulator 01:19:42 Bench test VSV Mini EGR Circuit: 01:25:47 Mini EGR Circuit with no vacuum at R port and some backpressure 01:29:30 Mini EGR Circuit with vacuum at R port and no backpressure Link for the EGR Valve replacement video: ua-cam.com/video/O3yb5RIlqPM/v-deo.html Link for the VSV Video: ua-cam.com/video/1Z-sy6z14D8/v-deo.html Thanks for watching! Please leave any tips, comments, or question in the Comments section. And thanks for 1,200 Subscribers! Good luck with your repair!
I have a 1997 4 door, 2 wheel drive with a P0401 code. Using the content in this video I determined the culprit was the VSV. During the bench test it would hold a vacuum, but unlike in the video mine would immediately release the vacuum within 3 seconds or so. Also unlike the spec of 33-38? ohms, mine was 78-80 ohms so I ordered a new VSV. While waiting for the part to arrive I replaced all the vacuum lines and reinstalled all parts. After a few days of driving the check engine light went out. While I did not find any leaks in the original vacuum lines I suspect that the VSV began to function better possibly because I had messed with it during the testing. I was able to lift the vehicle a few inches and reach the VSV using a 1/4" ratchet with a short extension. I did not need to loosen or remove anything else to gain access to the VSV. My vehicle does not have ABS but had the screw in the firewall. I installed the VSV on the firewall and was able to remove the old and replace it easily when the new one came in the mail. It took about 15 minutes to install the new one and I did not need to move the battery tray. Thanks again for the helpful video L35 in Colorado.
Wow, great job, and thanks for the update! Yes, a trouble VSV's can be hard to pin down as the exact cause because it can sometimes fail intermittently, which sounds like your case. Thanks for adding your tips for the 2WD, too, and thanks for watching! : )
Great Video!!! Thanks for taking the time to do this so thoroughly! Before I found your video, I did the 3 main tests most other video's demonstrate. They all end up at a bad VSV if the other 2 options test good, and mine did. I've now replaced the VSV twice but still get the Check Engine Light. So, I took the RAV to a mechanic and he says its the computer. Is that a common reason for a P0401 code? I dont really want to rush out to spend $200-$400 for a computer. Thanks...
No, that is not common, but it is possible -- however, I would check the whole circuit wiring before condemning the computer/ECU (unless he's already pinned-out the computer and confirmed a bad signal). The Rav4 ECU's seem to last forever and are not often the cause of any issue (though possible). If you have a junkyard in your area, the computers are usually only about $30 -- just be sure to match the part number with yours, because they are specific to transmission type (ie, 4WD, AWD, auto, 5-speed). I hope that helps!
Great information I was wondering if engine Temperature was a cause and effect of the OD (Over Drive) circuit.. Because I got the 1997 Rav4 it did not have the Thermostat in stalled in the engine and it takes a while for the OD kick in. So I know I need to have the Thermostat installed to get my OD to work correctly
@@L35inColorado Correct.. My Over Drive does not engage until my Temp of my car reaches just above the cold line on my 1997 Rav4 and I was wondering if Temperature had something to do with this. Even driving at 65MPH @ 3500 RPM.. I will not engage until it reaches about an 1/8" above the cold level indictor line on the Temperature Gauge.. I did not remove the Thermostat but believe the previous owner did.. I'm going to verify if its missing or stuck in the open position and replace it..
@@mikeespitia2813 Okay, thanks - according to the Toyota FSM-D, these are the minimum coolant temperatures required for the ECM to allow OD to engage: - A540H (4wd models): 60 Celsius (140 F) - A247E (2wd models): 55 Celsius (122 F) The FSM-D states that below those temperatures, the ECM "prohibits" overdrive engagement. According to the circuit diagram, the ECM receives the coolant temperature via the Engine Coolant Temperature sensor; the sensor location is shown in this video: ua-cam.com/video/9GxATev-cc8/v-deo.html So, yes - if the previous owner removed the thermostat or the thermostat failed in the open position, the engine/coolant will take much, much longer to warm up than normal, and as long as that Coolant Temp Sensor is sending a low temperature value to the ECM, the ECM will electronically prohibit OD from engaging. I think you're on the right path by investigating the thermostat. If your thermostat proves to be present and functioning well, then perhaps the next item to check would be the Coolant Temp sensor (the one shown in the video above). To test that sensor in place, you can either backprobe the sensor while its plugged in, or you can unplug the electrical connector after shutting off the engine and use your ohmeter/multimeter on the two terminals. Check for values at both engine cold and engine warm conditions, and see if your measured resistance is within the range shown on this chart: www.rav4world.com/threads/engine-coolant-temperature-sensor.302077/ I hope that helps! Be sure to fully bleed your coolant system after opening it up for that thermostat. If you're not familiar with bleeding, I show how to do it here: ua-cam.com/video/TbOr7gvqSqc/v-deo.html Good luck! : )
@@L35inColorado Thank you very much for all this information and since I have not purchased a service manual. Your videos and others I have watched give me great information on trouble shooting and vehicle operation and service.. 😁😁😁
I was wondering if you have a Video on installing the Thermostat. The ones I have watched on UA-cam show the Oil Filter Needs to be removed to access the hardware to remove the water inlet housing. Would a Crows Foot be a better approach on this Replacement or a universal drive adapter work better. Just Asking..
Great video. Please clarify, I read the VSV is normally closed so it should hold vacuum but you suggest it is open(not hold vacuum) and closes when energize.
It can be confusing because some Toyota VSV's use an opposite logic (I believe even some in the earlier 5SFE and 3SFE set-ups). But for this particular VSV shown (ie, the part # shown here for the Rav4), here is how it works: - when the VSV is *not* energized, the internal VSV vent is closed (blocked), which means that the VSV is sealed and so it *will* hold vacuum (and then EGR valve opens); - when the VSV *is* energized, the VSV vent is open (not blocked, open to atmosphere), which means that the VSV is not sealed and so it will *not* hold vacuum (and then EGR valve closes). To see this visually, check out the VSV bench tests shown at about 01:21:17. Also, here is a different video that shows more about the Rav4 VSV (replacing, testing, etc): ua-cam.com/video/1Z-sy6z14D8/v-deo.html I hope that helps! Good luck : )
Thank you for your time and videos. I have a 96 AWD 4DR Rav4 179,000 miles. Never( knock on wood had anything major to do on it. Have a pesky oil leak drips on passenger front that mechanic says it's very little and just monitor it and refill as needed cause to get to it you have to do something at the front. Wanted to ask you, when you took out the filter from the vacuum modulator, how to clean if dirty? Also i notice a book you are using as reference for readings, what book is that and where can I obtain a copy of it? It should also have the O2 sensors specifications, correct? I changed the pre-cat (Bank1Sensor1 cause i had a code P0133 and it fixed that issued but then iafter driving over 50 miles , i get a P0441 code, just trying to figure that one out. Am trying to change the O2 on the Bank 1 Sensor 2 (post-CAT). I think in one of your other videos you mentioned something about the heat shield. I may have to go under car cause there is a bolt that is kind of blocked by one of the fans. Anyway thank you again. Have a great day.
Thanks! The oil leak on the passenger side is very likely the oil pump housing seal, which is a job that you'll want to do next time you replace the timing belt (you have to remove the timing belt to reach it). I have a video on that full procedure, and here's the part about that leak source: ua-cam.com/video/TbOr7gvqSqc/v-deo.html Your mechanic is correct that it is a big job, but it is do-able as a DIY if you a good selection of tools and time to work methodically. The book I'm using is the Toyota Factory Service Manual, Volume 2, for the '00 Rav4. I'm not aware of any electronic versions, but sometimes people post items on ebay, like this (I don't have this myself and can't attest to what it is): www.ebay.com/itm/394479539274 I believe this is the equivalent hard-copy for your '96 (your '96 has a different ignition system than my '00): www.ebay.com/itm/144471547819 You can also by a two-day pass for $20 from Toyota to access the Toyota TIS, here, and get all the latest info and full repair procedures, parts, etc: techinfo.snapon.com/TIS/Register.aspx As for your emissions issue: do you have a California or Federal version? If you're not sure, just lift the hood and look on the underside of the hood - there should be a white sticker with a simplified vacuum hose diagram and a note if you "CA" or California emissions.
I'm glad you liked the video and I hope it helps! Thanks for asking, but I don't have a tip jar -- I just want everyone who's interested to know more about their Rav4's so that we can keep these babies on the road! I love Rav4's. : ) I just like to help people learn to DIY, because it was others who taught me to DIY in the first, so we can all pay it forward. Thanks for your comment!
How do the more modern egr valve systems compare with with the one you showed. I have a 2010 Toyota Corolla and I can't even find the components you mentioned except maybe the vsv part? Good video though I learned a lot!
I'm sorry I missed your comment! Yes, as you point, out, the systems are different on the newer models. The Gen-1 Rav4's system was designed in the late '80s and isn't used anymore. The newer system have some electronic components (ie, they often have solenoids on the EGR valves) and so they look quite different than the "old-fashioned" system seen here! Thanks for watching : )
When starting the enngin, the VSV does not exert Vaccum suction on white hose terminal on the EGR, so the pin or pitel inside the EGR is closed, now the exhaust gas returning from the engine goes into the V modulator and push the diaphragm up closing the T shape connector, by this action the air now comes only from P port and this P to Q pipe never close under any condition, in fact the P/Q is a constant suppl of air from 2 opining, P and [lower T] this lower T suckes the air from R port within a sealed space. It seems confusing, but once you digest the information, then all the great test which you have explained..... Will fit perfectly.
hello. first! great detailed video! just purchased a 96 awd rav4. once the car is warmed up its idles real low and sometimes stalls. while this was happening I was able to pop the white hose off the egr valve and the car then started to idle normal. what can be the cause of this ? car is throwing codes 401 and 402. thank you
Please answer if you still around. open the Vaccum Modulator and re exam the mechanism of this gadget. I think you were confused, as I said... Q port create a suction Vaccum at the start from P and R terminals, later.... Q continue to get air from P terminal only because, the diaphragm when pushed up seal the lower part of T shaped connector pipe, at this condition the air which comes from R may scap or partially released through the ting designated hole at the upper plastic cover.
I have a 2001 camry with similar set up as the rav4. I replaced all three components mentioned in this video at the same time and perform all test accordingly, no problems and I still get P0401 EGR Flow insufficient. Also cleaned exhaust port and pipe, checked all vacuum hoses(no leaks). Any suggestions!!!
Can you also call the vsv on the cannister "Purge value solenoid?" I had a problem on mine so I check the resistance and it was really low. So when I replaced it everything was fine.
Yes, sometimes they are called that for the EVAP systems (not so much for these older EGR systems, I don't think, but perhaps), especially the newer designs. The different names can overlap because they have similar functions even though they are only different systems (ie, EVAP or EGR) because the systems have solenoids and valves that are similar since they control flow. I'm glad you figured out your problem -- great job!
I bought a new vsv from autozone and I did your key on test and it doesn't hold vacuum like you suggested. It only holds vacuum if I plug the other end with my finger. Is my 98 camry different or is the replacement vsv faulty ty
I looked up the VSV part number for the 2.2L '98 Camry), and it is Aisin VST-006, which is a different part number than the one seen in the video for the 2.0L Rav4 (even though they do look similar). I don't know off the top of my head if the Camry VSV has a reverse logic: I do know that some Toyotas have a reverse logic. But I took a look at this thread for a 5SFE, and the test description is the same as the 3SFE shown in the video, which indicates to me that they logic is the same: www.toyotanation.com/threads/vsv-for-egr-removal-diagnosis-and-relocation-5s-fe.428469/ What result did you get testing the new VSV with the "Key on" test? Also, have you verified that your vacuum hoses themselves are good and without leaks?
@L35inColorado The old vsv wouldn't hold a vacuum very long and would leak very fast doing your test. The new vsv holds a vacuum when applying vacuum to the yellow port and plugging the white hose. Key off and key on act the exact same way. I checked with my multi meter and the plug is getting 12v with key on. I replaced the vacuum hoses also. Just confused why vacuum isn't holding while the vsv is getting 12v like your video shows. To be clear I have my handheld pump connected to yellow side and not plugging the white side while energized and it will not hold vacuum, it only holds a vacuum if I plug white side. The car is running a lot smoother with way more power. So far, the engine light hasn't returned but usually takes a while for it to return.
Quick Question.. Now that winter is around the Corner.. What are the best tape of Fog Lights to install on this Vehicle.. Yellow or White.. LED or Halogen.. And if they are not stock.. How should they be Wired to your Car.. Directly to the Batter or through the Fuse Box. And do you have a Video..
I don't have fog lights on my Rav4, and don't know much about which types are best, but I'm sure you can find lots of info on either the rav4world.com forums or the toyotanation.com forums. I hope that helps - good luck : )
Yes - as seen during Test 1 at 35:05, if you apply vacuum to a good EGR valve, the valve will lift and allow exhaust gas to enter the intake. This causes a problem if it happens during idle conditions because the air-fuel ratio becomes unbalanced, as there's now way too much air for the idling condition (think of it as a big vacuum leak). As a result, the engine will either stumble or die. In the video, you can see that the engine stumbles then dies when the EGR valve is opened during idle. I hope that helps : )
Can you come fix my car 97rav4 stalling issues and won’t accelerate at times don’t know if it is a fireing issue or egr/vacuum and your video was excellent excellent excellent oh and did I say excellent
Oh man, I'm sorry that's happening - you might check the spark plugs for oil. Eventually the spark plug tubes on these Rav4's need to be resealed, because the original RTV deteriorates and some oil ends up on the spark plugs, which causes firing issues and stalls. Sometimes this will prompt a check engine light (with a corresponding misfire code), but sometimes it doesn't cause a check engine light even though the driving performance is poot. To check, you can just remove the spark plugs: if they have oil on them, then that's likely the problem. There are many other possible issues that can cause the misfire/stutter/stall conditions, but that's where I'd likely start on this particular engine. I hope that helps! : )
The rpm keeps fluctuating at 2000 going up and down, cleaned the throttle body, didnt work out, any idea how to fix it? Checked the vacuum hoses also, no leakage
Ah man, I'm sorry that's happening -- has the coolant system been opened lately? I ask because if the coolant system wasn't completely bled, the air bubbles can cause a few sensors (ECT, IAC) to really go haywire, especially on idle. I would try a coolant bleed: I show the procedure at the end of this video -- you can use the timestamps in the Pinned Comment of that video to skip to the bleed: ua-cam.com/video/Y2My0ObSfcE/v-deo.html
@@L35inColorado no it hasn't been opened lately, could it be the intake manifold gasket? Should i try replacing the iac valve? It also fluctuates when driving.... Can the spark plugs cause this? Im lost and I recently changed the wiring for the spark plugs but not the spark plugs
@@johnnynahas8972 Okay, so you can probably rule out air in the coolant system (assuming your coolant level is steady). Regarding the intake gasket -- it is possible, yes, but the Rav4 has a metal intake gasket, so they don't typically fail unless the engine was overheated. Try this: pull each of the spark plugs, and been sure that they don't have oil on them. There is a common leak on these engines that just happens over the years where the RTV that seals the bottom of the spark plug tubes deteriorates and oil from the head seeps onto the spark plugs. This causes a misfire. This will eventually happen on just about every high-mileage 3SFE engine. Check that. Good luck!
Do you know by any chance the vsv part number? I have a 1999 rav4 awd and I'm having problems finding the valve. I don't live in California so it's a different valve. Also apparently they have two vsvs.
Yes, there are two VSV's, but they are for different systems. The VSV shown here is the "VSV for the EGR system". The part Toyota part number is 90910-12100, or Asin VST-034. The other VSV is the "VSV for the EVAP system", which is a different system. That VSV is located on the charcoal canister, and it is shaped differently. I am not aware of any differences in the VSV for EGR between the California and non-California models. The Rav4 in the video is an non-California model. Here is a complete video on the VSV replacement, which includes testing, and shows a '00 AWD: ua-cam.com/video/1Z-sy6z14D8/v-deo.html I hope this helps! Good luck!
To find the valve follow the vacuum lines from intake manifold. Then from whatever VSV you fi d continue follow lines to other component, that should identify the system.
I just got my 96 Rav4 out here in Colorado from CA and I am having issues with the gas pedal getting stuck while in 3rd gear do you think it is a throttle issue? I was thinking it might from the drastic climate change
Yes possibly -- for a sticky gas pedal, you want to be sure that the throttle body is clean inside where the plate travels, so that the plate can travel unobstructed. If that's cleaned and there's no difference, then I would check the throttle cable itself. The throttle links between the throttle body and gas pedal are just levers and cables (not electronic like newer cars), so there are places where the levers might get obstructed or the cable might have too much slack (they stretch over time). You can adjust out the slack at the throttle body (where the cable ends at the throttle body), and there are videos which show that. But hopefully you'll get it fixed by just cleaning up the throttle bottle and throttle plate area! As for the climate difference between CA and CO, modern cars are designed to operate in all sorts of climates, so that is not a factor. Environmentally, the biggest difference between CA and CO is that CO is a higher elevation than CA, which is why you see 85 octane gasoline here. You can used 85 octane in your Rav4 here (you don't have to use 87) because the higher altitude means lower air pressure which allows the Rav4 engine to run on 85 octane without knocking. Good luck!
Hi.... Think with me.... The p to Q part... Never close! The diaphragm when pushed up... It close the lower part of the tee shape, but the flow is still going on.... Between P and Q. Listen please..... Q port sucks air from P and also from R... Like double hose bringing air from P also R...if the diaphragm is down or if there is Vaccum on the GER and the pin is up, hence more exhaust gas is dumping back into the manifold, nuturaly in this condition, both P and R sending air to Q port..... But..... When the EGR pin closed, then the exhaust gas goes to the module and push the diaphragm up.... Closing the lower part of T shaped, now the Air is coming only from P, and that air from R is trapped inside the gadget,...do you get it??
Hi, Thanks for you comments -- I have read through your comments and I'm not exactly clear with your question. Regarding the vacuum modulator, yes, adequate exhaust back-pressure on the bottom of the vacuum modulator diaphragm causes the diaphragm to move up, which seals the bottom of the "T" shape inside. When the bottom of the "T" is sealed ("closed") then there can be vacuum between P and Q due to suction at the throttle body end of . This is what I mean by "closed" -- "closed" as in a "closed circuit" (ie, flow occurs in a "closed circuit"; no flow in an "open circuit"). Adequate vacuum from R can also pull the diaphragm up, sealing ("closing") the "T" between P and Q. Does that answer your question?
@@L35inColorado Thanks for answering. I think Q port gets air from both side P and R, before the diaphragm closed the bottom of T, more air is needed at this particular moment, the when diaphragm close the bottom of T, at this time air comes only from P to Q. Air flow always running from P to Q, and the function of diaphragm to close the T bottom, just make the air to move through P port to Q only, preventing the R port from delivering air to Q. Q gets the air from the P port and from the bottom of T which in turn gets the air from R port. Q normally gets air from P and R. Closing T bottom, prevents air coming from R.
@@wolfduranti8735 Thanks for explaining your considerations further. By "air flow" I will assume that you mean negative air pressure (vacuum), since we are discussing the role of vacuum/negative pressure. Please correct me if that's not what you meant. It is true that the Q port is often in vacuum (negative pressure), especially during driving, but the Q port is not always in vacuum. The Q port experiences vacuum only when the vacuum modulator's internal "T" is closed/sealed due to the diaphragm moving up and sealing ("closing") the bottom of the "T". When the bottom of the vacuum modulator "T" is not sealed (ie, when the "T" is "open"), the open "T" allows atmospheric pressure (positive pressure) from the little vent on the top of the vacuum modulator to prevent vacuum (negative pressure) from occurring in the "T" and therefore to prevent vacuum at Q. When this occurs, there is no vacuum (negative pressure) at Q, and the Q port is simply at atmospheric pressure. This condition occurs, for example, during idling, and can be seen in the video in Test 5 (54:05). In Test 5, the vacuum gauge is connected to the Q port (the large black pressure gauge on the left). As seen in that test, before the engine is started, pressure at Q is simply at atmospheric pressure (gauge pressure "zero"). When the engine is started and idling, there is no change on the pressure gauge at Q, and Q remains at atmospheric pressure (gauge pressure "zero"). However, when the throttle body is opened and engine speed is increased, the vacuum modulator diaphragm moves up and closes/seals the "T", which creates a sealed path between P/R and Q. Once this path is sealed, then negative pressure (vacuum) at the throttle body can reach Q, and we see vacuum at Q (negative pressure on the gauge). Finally, when the throttle body is closed and engine returns to idle speed, we see Q return to atmospheric pressure (gauge pressure "zero") because the "T" is no longer closed and the vent allows atmospheric pressure to negate vacuum. This video might also be useful for your investigation: ua-cam.com/video/uo9gdQ7ZhZ0/v-deo.html I hope this is helpful for you : )
@@L35inColorado you by all means excellent. Now wat is the relation between Q and R, at Normal atmosphere condition as you like to name it?? I think that pin point vent at the top of the modulator, is meant to let out the extra air coming from port R when T bottom is closed. I keep in mind the location of those orifices i.e P exactly on the throttle plate, and R 2 mm outside the throttle plate edsge. I know it is a bit confusing, and most likely we are on the same page, but I am unable to put the thought on writing. Thanks 🙂
@@wolfduranti8735 Q does not experience vacuum directly from R. The vacuum source for Q *directly* is P/E. The purpose of vacuum at R is to lift the diaphragm and seal the "T". When the "T" is sealed, vacuum at P affects Q. This is seen in the bench test at 01:15:49. Think of it this way: the air intake is the vacuum (negative pressure) source for the system. That negative pressure (vacuum) can affect P/E only when the throttle plate moves a little bit because then the little hole to P/E is not obstructed by the throttle plate. When that happens (when negative pressure affects P/E), it is then the position of the diaphragm in the vacuum modulator which determines whether or not that negative pressure (vacuum) can affect Q. The possibilities are either "yes" or "no," given by the following conditions: - If the vacuum modulator diaphragm is DOWN, then the "T" between P and Q is not sealed, so negative pressure at P/E cannot affect Q; - If the vacuum modulator diaphragm is UP, then the "T" is sealed, and negative pressure at P/E can affect Q. Next, whether or not the diaphragm is up and the "T" is sealed/closed is dependent either on: 1.) the pressure at R -- if R is under enough negative pressure (vacuum) from the air intake, R can *pull* the diaphragm up and seal the "T"; or 2.) the exhaust back pressure (positive pressure) on the bottom of the vacuum modulator -- if there is enough exhaust back pressure on the bottom chamber of the modulator, that positive pressure can *push* the diaphragm up and seal the "T". So, the "T" can seal either by positive pressure (exhaust pressure) or by negative pressure (intake vacuum). R is the method for sealing the "T" via intake vacuum. The presence of the little vent hole on the upper chamber of the vacuum modulator means that the upper chamber of the vacuum modulator is never sealed as a whole, meaning that air can always be sucked *into* the upper chamber if the upper chamber is under vacuum. Even when the upper chamber is not under negative pressure (vacuum) from the intake, it is still under atmospheric pressure due to this little hole. However, within the upper chamber itself, when the "T" is sealed, the connection between P and Q *is* sealed as a closed system between the air intake and the EGR valve or VSV (depending on the VSV position). So the upper chamber itself remains open to atmosphere, but the "T" itself can be sealed within the chamber. When the diaphragm drops and unseals the "T", then the system is not closed and the path from the intake to Q is again open to atmosphere via that little vent hole. Recall that the upper chamber is under vacuum when the throttle plate moves enough to allow intake vacuum to affect P/E (you can also see this by tee-ing in your vacuum gauge to the short hose that runs from the throttle body E port to the modulator P port; run the engine and turn the throttle plate while watching the gauge to see how plate movement affects the pressure). The bottom chamber of the vacuum modulator is also open to atmosphere through the exhaust system. So, neither side is a closed system: it is only the "T" that can be closed/sealed, and it is only closed/sealed when the diaphragm has moved up. So, to recap -- the little vent does not let air "out", but rather it allows air *in*: the language is very confusing because this is commonly called a "vacuum leak" in English, but strictly speaking there is no such thing as a "vacuum leak", as vacuum can't "leak" because vacuum is negative pressure (vacuum can't "flow" either, but we say that too!). So a "leak" in a vacuum system causes outside air to rush in (not "vacuum to leak out" even though we say that). But, for convenience we say "vacuum leak" as a way of visualizing it, even though it's not a good description of what's actually happening. This is a common point of confusion, but as you said, it is difficult to put some of this into words and so diagrams and pictures are better. : ) Along those lines, please have a look at this document here, which includes a cross-section of the vacuum modulator: www.toyotaguru.us/engine-control-systems/egr-vacuum-modulator.html There is another document that I think you'd find useful, and I'm trying to find a link for it -- if I find it, I will make another comment with a link to it. I hope this helps : )
![How Toyota EGR Modulator works [Everything you need to know!]](http://i.ytimg.com/vi/uo9gdQ7ZhZ0/mqdefault.jpg)
Outstanding and comprehensive videos (this one and for EGR and VSV troubleshooting)!! I change the valve cover gasket, on my wife's 1998 Rav4, and soon afterwards it sounded like the valves were clacking while the engine was loaded at 2G just before automatic transmission made a shift up in gear. Originally thought and feared I would have to remove valve cover again to perhaps adjust valves. After 3+ months, a P0401 code came out. Thanks to your videos I have a gameplan to troubleshoot my EGR components! Thank You!!
Thank you, and thanks for watching! : )
Your videos are invaluable for gen 1 Rav4 owners. Thank you for all your efforts!
Wow, thank you! : )
Seriously though. These are amazing videos. So clear and concise and well explained. And the video and audio quality are awesome. I would pay money for these for real. Wheres your Patreon? 🤩
You are a great teacher. Even better than all the men that I have watched so far
Thanks, and thanks for watching! : )
You're the BEST Instructional Toyota Mechanic on UA-cam!
I've learned so much, and with your help, fixed all kinds of problems on all of our family cars...saving all of us big bucks!
With your HELP, I can usually do the diagnostics, buy the right tools and parts, and get the problem fixed RIGHT the FIRST TIME!
Please keep up the GOOD WORK!!
It is stunning how complete and brilliant this video is!!!! It puts all other toyota egr videos to shame!!!!
Wow, thanks! Good luck : )
I am at owe with everything in this video… the level of detail, structuring, information…the editing, description….it is all above and beyond. Thank you so much for the effort. I’m trying to fix my sister’s 97 RAV4 and this is exactly what I needed. Again, thank you for this educational video! I learnt so much!
Wow, thank you so much, and thanks for watching! : )
Great job making your videos! In my case my 2000 RAV4 failed the vacuum to EGR valve test due to a completely clogged port on the intake manifold where the egr bolts to the manifold. Cleaned the port and all is good! Thanks! You rock!
Nice - well done on your DIY! I'm so glad the video helped. Thanks for watching! : )
Very thorough walk through of the EGR system that allowed me to diagnose the source of my P0401 OBD code: the EGR valve had blocked up with carbon deposits over the course of 240K miles so it failed Test 1 in the video. I cleaned the EGR valve and manifold port with carburetor cleaner, reinstalled it, and the OBD status is OK. Great video
This is the most comprehensive video regarding EGR. I don’t own a RAV4, but I do own land cruiser from that period. Therefore, the component is identical. Thanks for the Awesome course.
Wow, that's great - please add any tips you can share with your Land Cruiser job! Thanks for watching : )
It's been awhile since you posted this video yet timely and informational like being in a mechanics seminar,,, thanx for presentation on the EGR Circuit.😊😊
Thank you, and thanks for watching! : )
Really excellent video. Ultimately thorough, non patronizing, well organized. This is the best video of this type I have seen. Thank you.
Thanks, and thanks for watching! : )
I have an '89 Toyota pickup and found that your detailed component tests for individual EGR components could be reused to test the components in my truck without difficulty. Thank you! Your bench tests are fantastic and go above and beyond the FSM - was able to diagnose my problem in 10 mins after fully digesting your video. Happy New Year! I should add that you taking the time to make careful indices/a table of contents is just astoundingly useful for going back and refreshing specific procedures after the fact.
Wow, that's so great - excellent diagnosis on your pickup! I'm so glad the video helped, and I'm glad you like the timestamps (I like to jump around while watching videos, too, which is why I like to include timestamps) Happy New Year to you, too and thanks for watching! : )
By understanding how exactly a system works , it makes the repair is so much easier.. Exce;llent video!!
Thank you, and thanks for watching! : )
As always L35, super instructive video. My RAV EGR issue back 2008 turned out to be the VSV with the in-engine vacuum test. Interesting, but the hose to the MAP you mention developed a small crack leak and caused an idle issue a few years ago.
Love your calm, clear and assured demeaner. The videos are well lit and the post production graphics help a lot! Thank you very much and keep up the good work!
Thank you, and thanks for watching! : )
Thank you! This video helped with a P0402 issue on my 1999 Tacoma. The VSV was bad. Your detailed explanations in this video helped me troubleshoot my issue
Wow, that's great! Excellent work on your DIY -- thanks for sharing, and thanks for watching! : )
this is the coolest interaction i've seen on youtube. reminds me of my chem labs in high school lol. 2000 rav4 owner btw!
Wow, thanks! And thanks for watching : )
Thank you very much, rav 4 gen 1 owner here.
Thanks for watching!
@@L35inColorado i am planning on replacing some vacuum hoses for the egr. Would you happen to have a link for the specs? Thank you. (Will replacing it with silicone type be good?)
Always looking forward to your excellent instructional videos. You go above and beyond. I still have my 99 toyota rav 4door running great. 245,000 miles. Muchas gracias paz stay safe
Thank you! I hope to get my '00 up to your mileage. She has about 207K miles right now, and still runs great. Thanks for your comment and take care!
What kind of gas u use
My vacuuum modulator diaphragm went bad causing P0401. One junkyard trip and $14 later, problem fixed with a replacment from a junk rav. Who knows how long that will last but i got a spare VSV, vacuum hose set, and EGR oem valve too just in case. Wow, the vsv is so easy to get to on front wheel drive models. Was able to stick a long extension up to the 12mm vsv bolt and unbolt in 10 seconds. Very different experience from my AWD manual Rav...
Thank u for the great video
Thanks for 1,200 Subscribers!
Links for the EGR Valve and VSV replacement videos are below the Timestamps:
EGR Components Detailed Explanation:
00:01:10 What is EGR (Exhaust Gas Recirculation)
00:01:50 Path of Exhaust Gas from Exhaust Manifold to Intake
00:02:27 EGR Valve location and begin explanation
00:02:28 EGR Pipe location
00:03:08 EGR Valve in hand
00:04:15 EGR pintle when under vacuum
00:06:17 Connection between EGR Valve and Vacuum Modulator
00:06:35 The two "sides" of the EGR circuit (vacuum side and exhaust side)
00:07:13 VSV, Vacuum Switching Valve explanation
00:08:59 VSV with shorter hoses for demonstration
00:11:18 VSV under vacuum, not energized
00:12:37 VSV hooked up to 12v battery for demonstration
00:15:41 Vacuum Modulator explanation
00:16:52 Vacuum Modulator in hand
00:17:43 How to remove Vacuum Modulator
00:18:10 Opening the top of the Vacuum Modulator
00:19:18 Explanation of Q, R, and P ports of Vacuum Modulator
00:22:37 Vacuum sources at Throttle Body
00:23:40 Holes for Ports E and R
00:27:59 Role of ECU (engine computer) in EGR circuit
00:28:49 Role of MAP (Manifold Absolute Pressure) sensor in EGR Circuit
Begin Engine Tests:
00:30:44 Begin In-Engine Tests
00:30:51 Check all vacuum hoses for leaks
00:32:18 Check for vacuum at Throttle Body
00:35:04 Test 1: Check EGR Valve directly to see if it opens
00:39:50 Test 2: Check VSV function with Key OFF and Key ON conditions
00:46:10 Test 3: Check Vacuum Modulator for flow
00:47:59 Test 4: Check Vacuum Modulator for diaphragm response to backpressure
00:50:09 Prepare hose tees and gauges for next tests
00:51:36 Test 5: Check vacuum at Q port
00:59:17 Test 6: Check vacuum at EGR valve with engine cold
Warm up engine before Test 7:
01:01:10 Test 7: Check vacuum at EGR valve with engine warm
01:04:14 Test 8: Check vacuum at Q with full manifold vacuum on P
Bench Tests:
01:11:20 Bench test EGR Valve
01:13:27 Bench test Vacuum Modulator
01:19:42 Bench test VSV
Mini EGR Circuit:
01:25:47 Mini EGR Circuit with no vacuum at R port and some backpressure
01:29:30 Mini EGR Circuit with vacuum at R port and no backpressure
Link for the EGR Valve replacement video:
ua-cam.com/video/O3yb5RIlqPM/v-deo.html
Link for the VSV Video:
ua-cam.com/video/1Z-sy6z14D8/v-deo.html
Thanks for watching! Please leave any tips, comments, or question in the Comments section.
And thanks for 1,200 Subscribers!
Good luck with your repair!
Yes am really impressed by the explanation, this part egr have been confusing me.thanks alot
I'm glad the video is helpful -- good luck! : )
Very good videos everything explained very thoroughly and clearly at an easy to understand pace.
I don't subscribe to people channel but I see you smart and give helluva information so I subscribed and I hope it helps you.
Thank you! I hope the videos are helpful : )
I have a 1997 4 door, 2 wheel drive with a P0401 code. Using the content in this video I determined the culprit was the VSV. During the bench test it would hold a vacuum, but unlike in the video mine would immediately release the vacuum within 3 seconds or so. Also unlike the spec of 33-38? ohms, mine was 78-80 ohms so I ordered a new VSV.
While waiting for the part to arrive I replaced all the vacuum lines and reinstalled all parts. After a few days of driving the check engine light went out. While I did not find any leaks in the original vacuum lines I suspect that the VSV began to function better possibly because I had messed with it during the testing.
I was able to lift the vehicle a few inches and reach the VSV using a 1/4" ratchet with a short extension. I did not need to loosen or remove anything else to gain access to the VSV. My vehicle does not have ABS but had the screw in the firewall. I installed the VSV on the firewall and was able to remove the old and replace it easily when the new one came in the mail. It took about 15 minutes to install the new one and I did not need to move the battery tray.
Thanks again for the helpful video L35 in Colorado.
Wow, great job, and thanks for the update! Yes, a trouble VSV's can be hard to pin down as the exact cause because it can sometimes fail intermittently, which sounds like your case. Thanks for adding your tips for the 2WD, too, and thanks for watching! : )
you are Great! thank for all the time to take this awesome vid.
Awesome video
Teşekkürler bilgiler için ❤️
Great video I learned a lot thanks
Thanks! I hope the video helps, and good luck! : )
GENUINELY AND TRULY LOVE YOU WOW THANK YOU
Thank you, and thanks for watching! : )
Awesome! Thank you so much!
You're welcome -- good luck! : )
Once again YOU ROCK!!
You did a good job. You should be an instructor someday!
I don't know enough to be an instructor, but thanks for watching : )
@@L35inColorado I think you're close!
Great Video!!! Thanks for taking the time to do this so thoroughly! Before I found your video, I did the 3 main tests most other video's demonstrate. They all end up at a bad VSV if the other 2 options test good, and mine did. I've now replaced the VSV twice but still get the Check Engine Light. So, I took the RAV to a mechanic and he says its the computer. Is that a common reason for a P0401 code? I dont really want to rush out to spend $200-$400 for a computer. Thanks...
No, that is not common, but it is possible -- however, I would check the whole circuit wiring before condemning the computer/ECU (unless he's already pinned-out the computer and confirmed a bad signal). The Rav4 ECU's seem to last forever and are not often the cause of any issue (though possible). If you have a junkyard in your area, the computers are usually only about $30 -- just be sure to match the part number with yours, because they are specific to transmission type (ie, 4WD, AWD, auto, 5-speed). I hope that helps!
My 94 Land Cruiser thanks you! And so do I lol
Nice, thanks for watching! : )
Beautiful work- thorough understanding - clear-articulated well thanks for all your help. #womenDoinBIGthangz
Wow, thank you for your comment! And thanks for watching -- I hope the video helps and good luck! : )
Great information I was wondering if engine Temperature was a cause and effect of the OD (Over Drive) circuit..
Because I got the 1997 Rav4 it did not have the Thermostat in stalled in the engine and it takes a while for the OD kick in.
So I know I need to have the Thermostat installed to get my OD to work correctly
By OD circuit, do you mean the overdrive circuit on an automatic transmission?
@@L35inColorado Correct.. My Over Drive does not engage until my Temp of my car reaches just above the cold line on my 1997 Rav4 and I was wondering if Temperature had something to do with this. Even driving at 65MPH @ 3500 RPM.. I will not engage until it reaches about an 1/8" above the cold level indictor line on the Temperature Gauge.. I did not remove the Thermostat but believe the previous owner did.. I'm going to verify if its missing or stuck in the open position and replace it..
@@mikeespitia2813 Okay, thanks - according to the Toyota FSM-D, these are the minimum coolant temperatures required for the ECM to allow OD to engage:
- A540H (4wd models): 60 Celsius (140 F)
- A247E (2wd models): 55 Celsius (122 F)
The FSM-D states that below those temperatures, the ECM "prohibits" overdrive engagement. According to the circuit diagram, the ECM receives the coolant temperature via the Engine Coolant Temperature sensor; the sensor location is shown in this video:
ua-cam.com/video/9GxATev-cc8/v-deo.html
So, yes - if the previous owner removed the thermostat or the thermostat failed in the open position, the engine/coolant will take much, much longer to warm up than normal, and as long as that Coolant Temp Sensor is sending a low temperature value to the ECM, the ECM will electronically prohibit OD from engaging.
I think you're on the right path by investigating the thermostat. If your thermostat proves to be present and functioning well, then perhaps the next item to check would be the Coolant Temp sensor (the one shown in the video above). To test that sensor in place, you can either backprobe the sensor while its plugged in, or you can unplug the electrical connector after shutting off the engine and use your ohmeter/multimeter on the two terminals.
Check for values at both engine cold and engine warm conditions, and see if your measured resistance is within the range shown on this chart:
www.rav4world.com/threads/engine-coolant-temperature-sensor.302077/
I hope that helps! Be sure to fully bleed your coolant system after opening it up for that thermostat. If you're not familiar with bleeding, I show how to do it here:
ua-cam.com/video/TbOr7gvqSqc/v-deo.html
Good luck! : )
@@L35inColorado Thank you very much for all this information and since I have not purchased a service manual. Your videos and others I have watched give me great information on trouble shooting and vehicle operation and service.. 😁😁😁
I was wondering if you have a Video on installing the Thermostat. The ones I have watched on UA-cam show the Oil Filter Needs to be removed to access the hardware to remove the water inlet housing. Would a Crows Foot be a better approach on this Replacement or a universal drive adapter work better. Just Asking..
Great video. Please clarify, I read the VSV is normally closed so it should hold vacuum but you suggest it is open(not hold vacuum) and closes when energize.
It can be confusing because some Toyota VSV's use an opposite logic (I believe even some in the earlier 5SFE and 3SFE set-ups). But for this particular VSV shown (ie, the part # shown here for the Rav4), here is how it works:
- when the VSV is *not* energized, the internal VSV vent is closed (blocked), which means that the VSV is sealed and so it *will* hold vacuum (and then EGR valve opens);
- when the VSV *is* energized, the VSV vent is open (not blocked, open to atmosphere), which means that the VSV is not sealed and so it will *not* hold vacuum (and then EGR valve closes).
To see this visually, check out the VSV bench tests shown at about 01:21:17.
Also, here is a different video that shows more about the Rav4 VSV (replacing, testing, etc):
ua-cam.com/video/1Z-sy6z14D8/v-deo.html
I hope that helps! Good luck : )
Thank you for your time and videos. I have a 96 AWD 4DR Rav4 179,000 miles. Never( knock on wood had anything major to do on it. Have a pesky oil leak drips on passenger front that mechanic says it's very little and just monitor it and refill as needed cause to get to it you have to do something at the front. Wanted to ask you, when you took out the filter from the vacuum modulator, how to clean if dirty? Also i notice a book you are using as reference for readings, what book is that and where can I obtain a copy of it? It should also have the O2 sensors specifications, correct? I changed the pre-cat (Bank1Sensor1 cause i had a code P0133 and it fixed that issued but then iafter driving over 50 miles , i get a P0441 code, just trying to figure that one out. Am trying to change the O2 on the Bank 1 Sensor 2 (post-CAT). I think in one of your other videos you mentioned something about the heat shield. I may have to go under car cause there is a bolt that is kind of blocked by one of the fans.
Anyway thank you again. Have a great day.
Thanks! The oil leak on the passenger side is very likely the oil pump housing seal, which is a job that you'll want to do next time you replace the timing belt (you have to remove the timing belt to reach it). I have a video on that full procedure, and here's the part about that leak source:
ua-cam.com/video/TbOr7gvqSqc/v-deo.html
Your mechanic is correct that it is a big job, but it is do-able as a DIY if you a good selection of tools and time to work methodically.
The book I'm using is the Toyota Factory Service Manual, Volume 2, for the '00 Rav4. I'm not aware of any electronic versions, but sometimes people post items on ebay, like this (I don't have this myself and can't attest to what it is):
www.ebay.com/itm/394479539274
I believe this is the equivalent hard-copy for your '96 (your '96 has a different ignition system than my '00):
www.ebay.com/itm/144471547819
You can also by a two-day pass for $20 from Toyota to access the Toyota TIS, here, and get all the latest info and full repair procedures, parts, etc:
techinfo.snapon.com/TIS/Register.aspx
As for your emissions issue: do you have a California or Federal version? If you're not sure, just lift the hood and look on the underside of the hood - there should be a white sticker with a simplified vacuum hose diagram and a note if you "CA" or California emissions.
Excellent, comprehensive explanation of the entire system, thank you. How can I contribute to your efforts? Tip jar?.
I'm glad you liked the video and I hope it helps! Thanks for asking, but I don't have a tip jar -- I just want everyone who's interested to know more about their Rav4's so that we can keep these babies on the road! I love Rav4's. : ) I just like to help people learn to DIY, because it was others who taught me to DIY in the first, so we can all pay it forward. Thanks for your comment!
How do the more modern egr valve systems compare with with the one you showed. I have a 2010 Toyota Corolla and I can't even find the components you mentioned except maybe the vsv part? Good video though I learned a lot!
I'm sorry I missed your comment! Yes, as you point, out, the systems are different on the newer models. The Gen-1 Rav4's system was designed in the late '80s and isn't used anymore. The newer system have some electronic components (ie, they often have solenoids on the EGR valves) and so they look quite different than the "old-fashioned" system seen here! Thanks for watching : )
When starting the enngin, the VSV does not exert Vaccum suction on white hose terminal on the EGR, so the pin or pitel inside the EGR is closed, now the exhaust gas returning from the engine goes into the V modulator and push the diaphragm up closing the T shape connector, by this action the air now comes only from P port and this P to Q pipe never close under any condition, in fact the P/Q is a constant suppl of air from 2 opining, P and [lower T] this lower T suckes the air from R port within a sealed space.
It seems confusing, but once you digest the information, then all the great test which you have explained..... Will fit perfectly.
Wow! The video is so good, detailed and well explained. It’s noticeable that you take it seriously.... thank you so much!!!!
Thanks
Thank you for watching! : )
hello. first! great detailed video! just purchased a 96 awd rav4. once the car is warmed up its idles real low and sometimes stalls. while this was happening I was able to pop the white hose off the egr valve and the car then started to idle normal. what can be the cause of this ? car is throwing codes 401 and 402. thank you
Ayuda, cuál de esas mangueras conectan al canister? En raf4 99
Please answer if you still around.
open the Vaccum Modulator and re exam the mechanism of this gadget.
I think you were confused, as I said... Q port create a suction Vaccum at the start from P and R terminals, later.... Q continue to get air from P terminal only because, the diaphragm when pushed up seal the lower part of T shaped connector pipe, at this condition the air which comes from R may scap or partially released through the ting designated hole at the upper plastic cover.
I have a 2001 camry with similar set up as the rav4. I replaced all three components mentioned in this video at the same time and perform all test accordingly, no problems and I still get P0401 EGR Flow insufficient. Also cleaned exhaust port and pipe, checked all vacuum hoses(no leaks). Any suggestions!!!
Can you also call the vsv on the cannister "Purge value solenoid?" I had a problem on mine so I check the resistance and it was really low. So when I replaced it everything was fine.
Yes, sometimes they are called that for the EVAP systems (not so much for these older EGR systems, I don't think, but perhaps), especially the newer designs. The different names can overlap because they have similar functions even though they are only different systems (ie, EVAP or EGR) because the systems have solenoids and valves that are similar since they control flow. I'm glad you figured out your problem -- great job!
I bought a new vsv from autozone and I did your key on test and it doesn't hold vacuum like you suggested. It only holds vacuum if I plug the other end with my finger. Is my 98 camry different or is the replacement vsv faulty ty
I looked up the VSV part number for the 2.2L '98 Camry), and it is Aisin VST-006, which is a different part number than the one seen in the video for the 2.0L Rav4 (even though they do look similar). I don't know off the top of my head if the Camry VSV has a reverse logic: I do know that some Toyotas have a reverse logic.
But I took a look at this thread for a 5SFE, and the test description is the same as the 3SFE shown in the video, which indicates to me that they logic is the same:
www.toyotanation.com/threads/vsv-for-egr-removal-diagnosis-and-relocation-5s-fe.428469/
What result did you get testing the new VSV with the "Key on" test? Also, have you verified that your vacuum hoses themselves are good and without leaks?
@L35inColorado The old vsv wouldn't hold a vacuum very long and would leak very fast doing your test. The new vsv holds a vacuum when applying vacuum to the yellow port and plugging the white hose. Key off and key on act the exact same way. I checked with my multi meter and the plug is getting 12v with key on. I replaced the vacuum hoses also. Just confused why vacuum isn't holding while the vsv is getting 12v like your video shows. To be clear I have my handheld pump connected to yellow side and not plugging the white side while energized and it will not hold vacuum, it only holds a vacuum if I plug white side.
The car is running a lot smoother with way more power. So far, the engine light hasn't returned but usually takes a while for it to return.
Quick Question.. Now that winter is around the Corner.. What are the best tape of Fog Lights to install on this Vehicle.. Yellow or White.. LED or Halogen.. And if they are not stock.. How should they be Wired to your Car.. Directly to the Batter or through the Fuse Box. And do you have a Video..
I don't have fog lights on my Rav4, and don't know much about which types are best, but I'm sure you can find lots of info on either the rav4world.com forums or the toyotanation.com forums. I hope that helps - good luck : )
CAN YOU PLEASE explain why engine stalls when you pull vacuum on a good EGR valve?
Yes - as seen during Test 1 at 35:05, if you apply vacuum to a good EGR valve, the valve will lift and allow exhaust gas to enter the intake. This causes a problem if it happens during idle conditions because the air-fuel ratio becomes unbalanced, as there's now way too much air for the idling condition (think of it as a big vacuum leak). As a result, the engine will either stumble or die. In the video, you can see that the engine stumbles then dies when the EGR valve is opened during idle. I hope that helps : )
@@L35inColorado Thanks
Can you come fix my car 97rav4 stalling issues and won’t accelerate at times don’t know if it is a fireing issue or egr/vacuum and your video was excellent excellent excellent oh and did I say excellent
Oh man, I'm sorry that's happening - you might check the spark plugs for oil. Eventually the spark plug tubes on these Rav4's need to be resealed, because the original RTV deteriorates and some oil ends up on the spark plugs, which causes firing issues and stalls. Sometimes this will prompt a check engine light (with a corresponding misfire code), but sometimes it doesn't cause a check engine light even though the driving performance is poot.
To check, you can just remove the spark plugs: if they have oil on them, then that's likely the problem.
There are many other possible issues that can cause the misfire/stutter/stall conditions, but that's where I'd likely start on this particular engine. I hope that helps! : )
The rpm keeps fluctuating at 2000 going up and down, cleaned the throttle body, didnt work out, any idea how to fix it? Checked the vacuum hoses also, no leakage
Ah man, I'm sorry that's happening -- has the coolant system been opened lately? I ask because if the coolant system wasn't completely bled, the air bubbles can cause a few sensors (ECT, IAC) to really go haywire, especially on idle.
I would try a coolant bleed: I show the procedure at the end of this video -- you can use the timestamps in the Pinned Comment of that video to skip to the bleed:
ua-cam.com/video/Y2My0ObSfcE/v-deo.html
@@L35inColorado no it hasn't been opened lately, could it be the intake manifold gasket? Should i try replacing the iac valve? It also fluctuates when driving.... Can the spark plugs cause this? Im lost and I recently changed the wiring for the spark plugs but not the spark plugs
@@johnnynahas8972 Okay, so you can probably rule out air in the coolant system (assuming your coolant level is steady). Regarding the intake gasket -- it is possible, yes, but the Rav4 has a metal intake gasket, so they don't typically fail unless the engine was overheated.
Try this: pull each of the spark plugs, and been sure that they don't have oil on them. There is a common leak on these engines that just happens over the years where the RTV that seals the bottom of the spark plug tubes deteriorates and oil from the head seeps onto the spark plugs. This causes a misfire. This will eventually happen on just about every high-mileage 3SFE engine. Check that. Good luck!
Do you know by any chance the vsv part number? I have a 1999 rav4 awd and I'm having problems finding the valve. I don't live in California so it's a different valve. Also apparently they have two vsvs.
Yes, there are two VSV's, but they are for different systems. The VSV shown here is the "VSV for the EGR system". The part Toyota part number is 90910-12100, or Asin VST-034.
The other VSV is the "VSV for the EVAP system", which is a different system. That VSV is located on the charcoal canister, and it is shaped differently.
I am not aware of any differences in the VSV for EGR between the California and non-California models. The Rav4 in the video is an non-California model.
Here is a complete video on the VSV replacement, which includes testing, and shows a '00 AWD:
ua-cam.com/video/1Z-sy6z14D8/v-deo.html
I hope this helps! Good luck!
To find the valve follow the vacuum lines from intake manifold. Then from whatever VSV you fi d continue follow lines to other component, that should identify the system.
I just got my 96 Rav4 out here in Colorado from CA and I am having issues with the gas pedal getting stuck while in 3rd gear do you think it is a throttle issue? I was thinking it might from the drastic climate change
Yes possibly -- for a sticky gas pedal, you want to be sure that the throttle body is clean inside where the plate travels, so that the plate can travel unobstructed. If that's cleaned and there's no difference, then I would check the throttle cable itself. The throttle links between the throttle body and gas pedal are just levers and cables (not electronic like newer cars), so there are places where the levers might get obstructed or the cable might have too much slack (they stretch over time). You can adjust out the slack at the throttle body (where the cable ends at the throttle body), and there are videos which show that. But hopefully you'll get it fixed by just cleaning up the throttle bottle and throttle plate area!
As for the climate difference between CA and CO, modern cars are designed to operate in all sorts of climates, so that is not a factor. Environmentally, the biggest difference between CA and CO is that CO is a higher elevation than CA, which is why you see 85 octane gasoline here. You can used 85 octane in your Rav4 here (you don't have to use 87) because the higher altitude means lower air pressure which allows the Rav4 engine to run on 85 octane without knocking.
Good luck!
Hi.... Think with me.... The p to Q part... Never close! The diaphragm when pushed up... It close the lower part of the tee shape, but the flow is still going on.... Between P and Q.
Listen please.....
Q port sucks air from P and also from R... Like double hose bringing air from P also R...if the diaphragm is down or if there is Vaccum on the GER and the pin is up, hence more exhaust gas is dumping back into the manifold, nuturaly in this condition, both P and R sending air to Q port..... But..... When the EGR pin closed, then the exhaust gas goes to the module and push the diaphragm up.... Closing the lower part of T shaped, now the Air is coming only from P, and that air from R is trapped inside the gadget,...do you get it??
Hi, Thanks for you comments -- I have read through your comments and I'm not exactly clear with your question. Regarding the vacuum modulator, yes, adequate exhaust back-pressure on the bottom of the vacuum modulator diaphragm causes the diaphragm to move up, which seals the bottom of the "T" shape inside. When the bottom of the "T" is sealed ("closed") then there can be vacuum between P and Q due to suction at the throttle body end of . This is what I mean by "closed" -- "closed" as in a "closed circuit" (ie, flow occurs in a "closed circuit"; no flow in an "open circuit").
Adequate vacuum from R can also pull the diaphragm up, sealing ("closing") the "T" between P and Q.
Does that answer your question?
@@L35inColorado Thanks for answering.
I think Q port gets air from both side P and R, before the diaphragm closed the bottom of T, more air is needed at this particular moment, the when diaphragm close the bottom of T, at this time air comes only from P to Q.
Air flow always running from P to Q, and the function of diaphragm to close the T bottom, just make the air to move through P port to Q only, preventing the R port from delivering air to Q.
Q gets the air from the P port and from the bottom of T which in turn gets the air from R port.
Q normally gets air from P and R.
Closing T bottom, prevents air coming from R.
@@wolfduranti8735 Thanks for explaining your considerations further. By "air flow" I will assume that you mean negative air pressure (vacuum), since we are discussing the role of vacuum/negative pressure. Please correct me if that's not what you meant.
It is true that the Q port is often in vacuum (negative pressure), especially during driving, but the Q port is not always in vacuum. The Q port experiences vacuum only when the vacuum modulator's internal "T" is closed/sealed due to the diaphragm moving up and sealing ("closing") the bottom of the "T".
When the bottom of the vacuum modulator "T" is not sealed (ie, when the "T" is "open"), the open "T" allows atmospheric pressure (positive pressure) from the little vent on the top of the vacuum modulator to prevent vacuum (negative pressure) from occurring in the "T" and therefore to prevent vacuum at Q.
When this occurs, there is no vacuum (negative pressure) at Q, and the Q port is simply at atmospheric pressure. This condition occurs, for example, during idling, and can be seen in the video in Test 5 (54:05).
In Test 5, the vacuum gauge is connected to the Q port (the large black pressure gauge on the left). As seen in that test, before the engine is started, pressure at Q is simply at atmospheric pressure (gauge pressure "zero"). When the engine is started and idling, there is no change on the pressure gauge at Q, and Q remains at atmospheric pressure (gauge pressure "zero").
However, when the throttle body is opened and engine speed is increased, the vacuum modulator diaphragm moves up and closes/seals the "T", which creates a sealed path between P/R and Q. Once this path is sealed, then negative pressure (vacuum) at the throttle body can reach Q, and we see vacuum at Q (negative pressure on the gauge).
Finally, when the throttle body is closed and engine returns to idle speed, we see Q return to atmospheric pressure (gauge pressure "zero") because the "T" is no longer closed and the vent allows atmospheric pressure to negate vacuum.
This video might also be useful for your investigation:
ua-cam.com/video/uo9gdQ7ZhZ0/v-deo.html
I hope this is helpful for you : )
@@L35inColorado you by all means excellent.
Now wat is the relation between Q and R, at Normal atmosphere condition as you like to name it??
I think that pin point vent at the top of the modulator, is meant to let out the extra air coming from port R when T bottom is closed.
I keep in mind the location of those orifices i.e P exactly on the throttle plate, and R 2 mm outside the throttle plate edsge.
I know it is a bit confusing, and most likely we are on the same page, but I am unable to put the thought on writing.
Thanks 🙂
@@wolfduranti8735 Q does not experience vacuum directly from R. The vacuum source for Q *directly* is P/E. The purpose of vacuum at R is to lift the diaphragm and seal the "T". When the "T" is sealed, vacuum at P affects Q. This is seen in the bench test at 01:15:49.
Think of it this way: the air intake is the vacuum (negative pressure) source for the system. That negative pressure (vacuum) can affect P/E only when the throttle plate moves a little bit because then the little hole to P/E is not obstructed by the throttle plate.
When that happens (when negative pressure affects P/E), it is then the position of the diaphragm in the vacuum modulator which determines whether or not that negative pressure (vacuum) can affect Q. The possibilities are either "yes" or "no," given by the following conditions:
- If the vacuum modulator diaphragm is DOWN, then the "T" between P and Q is not sealed, so negative pressure at P/E cannot affect Q;
- If the vacuum modulator diaphragm is UP, then the "T" is sealed, and negative pressure at P/E can affect Q.
Next, whether or not the diaphragm is up and the "T" is sealed/closed is dependent either on:
1.) the pressure at R -- if R is under enough negative pressure (vacuum) from the air intake, R can *pull* the diaphragm up and seal the "T";
or
2.) the exhaust back pressure (positive pressure) on the bottom of the vacuum modulator -- if there is enough exhaust back pressure on the bottom chamber of the modulator, that positive pressure can *push* the diaphragm up and seal the "T".
So, the "T" can seal either by positive pressure (exhaust pressure) or by negative pressure (intake vacuum). R is the method for sealing the "T" via intake vacuum.
The presence of the little vent hole on the upper chamber of the vacuum modulator means that the upper chamber of the vacuum modulator is never sealed as a whole, meaning that air can always be sucked *into* the upper chamber if the upper chamber is under vacuum. Even when the upper chamber is not under negative pressure (vacuum) from the intake, it is still under atmospheric pressure due to this little hole.
However, within the upper chamber itself, when the "T" is sealed, the connection between P and Q *is* sealed as a closed system between the air intake and the EGR valve or VSV (depending on the VSV position). So the upper chamber itself remains open to atmosphere, but the "T" itself can be sealed within the chamber. When the diaphragm drops and unseals the "T", then the system is not closed and the path from the intake to Q is again open to atmosphere via that little vent hole.
Recall that the upper chamber is under vacuum when the throttle plate moves enough to allow intake vacuum to affect P/E (you can also see this by tee-ing in your vacuum gauge to the short hose that runs from the throttle body E port to the modulator P port; run the engine and turn the throttle plate while watching the gauge to see how plate movement affects the pressure).
The bottom chamber of the vacuum modulator is also open to atmosphere through the exhaust system. So, neither side is a closed system: it is only the "T" that can be closed/sealed, and it is only closed/sealed when the diaphragm has moved up.
So, to recap -- the little vent does not let air "out", but rather it allows air *in*: the language is very confusing because this is commonly called a "vacuum leak" in English, but strictly speaking there is no such thing as a "vacuum leak", as vacuum can't "leak" because vacuum is negative pressure (vacuum can't "flow" either, but we say that too!). So a "leak" in a vacuum system causes outside air to rush in (not "vacuum to leak out" even though we say that). But, for convenience we say "vacuum leak" as a way of visualizing it, even though it's not a good description of what's actually happening. This is a common point of confusion, but as you said, it is difficult to put some of this into words and so diagrams and pictures are better. : )
Along those lines, please have a look at this document here, which includes a cross-section of the vacuum modulator:
www.toyotaguru.us/engine-control-systems/egr-vacuum-modulator.html
There is another document that I think you'd find useful, and I'm trying to find a link for it -- if I find it, I will make another comment with a link to it.
I hope this helps : )
Is this Michael Jackson !? He he he!
Haha, I wish I could dance like Michael Jackson! : )
2.2L DOHC Federal (non-California)
2000 Camry exactly
Вам муж не нужен?
Не вижу смысла выхлоп и другие отходы обратно пихать