I bought his paper version, it has already been worth the money. I came across his videos by accident, I am very impressed. I bought the book just after. I would recommend the book and the videos to all ages and levels of experienced techs.
It certainly couldn't hurt to do the test and as you said you would want to measure each side, unless it has an EGR system that would enable testing at that location. If it is normal at the EGR then checking each side wouldn't be necessary. If it is higher than normal then you would have to figure out which side is restricted.
One thing to note, on a car old enough to possibly be having a clogged exhaust issue. Many times the tiny passages going to the transducer or DPFE / EGR can become clogged. Although it is a different problem, it can prevent testing from these locations accurately.
ever test back pressure full load wot? i’ve tried for fun on my stock s2000 with high flow cat, I get 2psi back pressure before and after cat. then I tried on gfs rsx type s all stock, get about 8psi before cat, 2psi after cat. these are done wot hitting close to 8000rpm. just wondering if that’s normal. I get almost no back pressure under no load holding 3000rpm
Thank you for the recommendation for the Ford engines. Much more painless than getting to the front o2 on a 4.6. I previously tried the brake booster hose on a vacuum gauge and that didn't seem to provide accurate results. Will definitely try the DPFE method on my 99 Mustang GT.
Man your Awesome!! I just wanted to tell you thanks man I have a 98 crown vic police interceptor and i was going to have real trouble getting at the O2 sensor to do a back flow test and you showed that alternative way to check it! Thanks man your Videos are great and I always enjoy learning from you videos !!!
I had this problem with my old bronco II.t. Turns out an intermittent misfire issue I had days prior sent enough raw fuel down stream to melt the catalytic converter. Pulling the EGR exhaust tube and hearing it making a loud hissing noise confirmed the clogged exhuast. Gutting the cat, made fore a quick solution. Thats why I like OBD-1 no trouble codes for doing that!
Well that is a big difference for sure as this is a pintle position open code. Do me a favor, bolt the EGR back on. Take a reading on the signal wire with the engine off, then start the truck and give me another reading. It should not increase in voltage. If it does, you most likely bolted the EGR valve on backwards and vacuum is pulling the pintle open at idle. It can be done, I have seen it, however not all models have the clearance to bolt it on backwards but some do.
@ncrdisabled yes, it is melted and blocks the flow of exhaust gas through it. Also there is a cause of the cat. melting. It is never good to just change the cat. without finding out why it overheated. (misfiring, air/fuel problems etc.)
What about using this pressure gauge to measure the pressure after the cat. On the first test you obviously notice there was excessive back pressure, but you could not determine if it was from the cat or possibly the muffler (collapsed internally causing blockage). If you use the bung hole for the aft O2 sensor (yes sounds funny, but technically correct), the one aft of the cat, you could compare it to the reading forward of the cat. If the second is high, it is caused most likely by the muffler and if lower then the catalytic converter.
@contagiousFX Hey thanks for the comment. I am not sure about the snap throttle vacuum test. (I'll have to do more of them) I know John Thorton (awesome instructor, look him up) uses the MAP sensor signal for his plugged exhaust tests. But I know for a fact that the test where you hold the engine at 3000 and make sure vac. doesn't drop is not 100% accurate. I had a car with 5 psi of back pressure pass that test with flying colors.
@Mrgeemoney25 That works but only for severe restrictions. I have had car with 5 psi of back pressure at 3000 RPM like in this video that passed that vacuum test with no problem at all. Thanks for the heads up though. I think the vacuum test is only 100% when you do snap throttle testing. I'm just not real confident with the test results on that yet.
BTW I like a .8 of a volt closed valve position, just make sure it stays there at idle. The pintle should be facing the intake port NOT the exhaust port. In other words intake vacuum should be pulling the pintle down, not up. This also backs up the notion that it cannot be a plugged exhaust causing this as exhaust gas pushes against the pintle on the back side.
I just break out a drill bit and drill a thick spot of metal for a 1/4" pipe thread on the exhaust then tapping it put in a fitting then test it. When done you just put a 1/4" plug in and your done. Time to do is about 15 minutes.
Don't worry about the bi-directional control not working. What is EVP voltage KOEO and what is EVP voltage at idle? If the voltage rises significantly from KOEO to KOER then you most likely bolted the EGR valve on backwards and vacuum is pulling it open slightly. If voltage is high both times then most likely carbon on the seat and stem area is holding the valve open a little
Don't feel bad Paul, I've ripped the hoses off like that and broke some very weakened plastic nipples off the DPFE. Those parts see a lot of stress from the engine bay heat and exhaust gas heat. Not Ford's best idea.
Either one, I used to work for Pep Boys. But you have to find a store with a good driveability tech. the other stores in my area would send their "problem cars" to me. so it is kind of hit and miss. Same way at the dealer.
Wow, great info. I suspect a plugged cat on a buddys 4.6 f150 and am going to measure the back pressure at the egr tomorrow. Thanks for the usefull info!
@drm315 Yea, I thought that was interesting too. I really don't have an answer for that, it definitely could be a venturi effect. I don't think it was the gauge, I think it was actually a vacuum.
There is. Doing drive ability I always road test to verify the customer complaint. I always do this test during the road test, not in the bay. Drive the car till you get to where you feel a lack of power. From there move the throttle past where you are and back to that point again a bunch of times and watch the MAP sensors response.
My bad, its a p0404 code. According to GM service manual, code is set off when there is more than a 10% difference between the desired and actual position. Getting good ground and I tested the reference and power voltage and both come out good at 5 and 12 V respectively. I removed EGR and checked the voltage on the EVP and was getting about 0.8V with the pintle at rest and about 4.4V fully depressed. Smooth voltage change as I manipulated the pintle. Dont have a scan tool so I just used a DVOM.
Excellent testing on exhaust Pressure testing. About 15 yrs ago lbwas at a garage checking the electrics on a wagon, a fitter in the nexted bay had put a new exhaust flexy. On the exhaust system of a wagon, he started the wagon up.and was revving the engine, there was a massive Bang and he switched off the engine, l walked over to see what had happened, The exhaust flexy pipe had Burst open, you could put, Your fist in the hole, and he said that what happened to the original one that was on, I then said, you mean to stand there and tell me that, Did you not think of doing a pressure check on the exhaust system, those flexy Pipes are over 800 dollars Each. Don't think he knows what he is doing. More expense at somebody's in experience.
solved the problem. the control wire connection to the egr valve was hanging on by onky a few threads. the connection was hidden behind that rubber insert gm has behind the connector. you are right it was power side switch. why does the ground need to go to pcm as well?
Thanks for the reply. I was aware I might get codes with the new exhaust system, and I did eventually. But it does feel like it doesn't have the power it used to have, so when I first came across one of your exhaust pressure videos I thought it might be worth a shot checking to see if the cats did get overheated. There was a few misfire codes a year ago very briefly, but I think the code was for the coil pack. I don't know if this is the type of misfire that can hurt a cat or not.
The P0405 is described as "Pintle Position Circuit Low Voltage". A plugged exhaust would not set this code. You potentially have a wiring problem. What is the EVP signal wire voltage with the KOEO (key on engine off)? What does the scan tool show EVP voltage and % at also KOEO?
@turbobuick33 The first gauge in the video appears to be an OTC 7215 exhaust gauge. It has the same look and stainless steel braided line. See Tool Topia for a pic of if.
P1152 and P1132 is "lack of O2 switch, sensor indicates rich" and this is on both banks. So this suggests not an O2 problem but a rich running condition. (that matches your gas smelling oil too doesn't it?) there are a lot of different cause of rich conditions. fuel psi too high, fuel psi reg leaking (return type only), faulty MAF sensor, ECT sensor reading too cold, leaking injectors, bad head gasket, EVAP purge valve issues, timing chain issues, also I don't list a P0513 code? r u sure on that
if the control wire is shorted to ground that EGR solenoid would be energized all the time (on a ground side switched design) and open all the time. you never mentioned a rough idle which is what it would do. some of these were power side switched and with that design BOTH solenoid wires go to the PCM and one will have a constant ground.
I also have a dodge ram 05 with the 5.7L. Its throwing codes for both cats and some 02 sensors, but only occasionally. I wanted to perform this test on it anyways, but I was curious about the differences for vehicles with 2 cyl banks compared to 1, if any. For instance, I have long tube headers and high-flow cats, but they merge into a y-pipe after the cats and then into the muffler and exit out the same side. Should I take measurements at each of the 4 02 bungs? Should I start with the EGR?
I have been watching threw your videos. Lots of good stuff going on. With this one I was curious if you had experimented with engine vacuum, either vacuum gauge or MAP pids and TPS, to show a plugged cat?
Guy I used to work with would drill a small hole in the exhaust to test back pressure and then weld it back up when he was done. Not the way I would do it, but effective.
On your test on the G6 the gauge seemed to go to vacuum when raising the rpm. Is this a venturi effect or just the gauge bouncing? Great videos! Look forward to the next one.
Oh, ok. Did the cars with partially plugged cats have a drive ability problem related to the cat? or multiple issues?. I am just curious. I ran into an older Mercedes that had no easy access to back pressure testing but had all the symptoms of a plugged cat, and possibly more. The customer didn't want to spend any money on the car so I had to stop before I got a good chance to play with a vacuum gauge... All though I have had lots of success using MAP and TPS pid data on other cars.
If you have no low power complaints then I wouldn't worry about a backpressure test. This is not the test that is needed for a cat. code. In most cases the cat. code shows up way before it gets to the point of restricting the exhaust. My guess is your "high flow" aftermarket cats is what is setting the cat. codes. I'm afraid the only fix for that is to put the factory ones back on. I have ZERO luck with aftermarket cats. They just don't meet the OEM standards.
Good video!!! What are you thoughts concerning a standard exhaust vs a performance exhaust. Which exhaust is better for the engine a properly fitted standard exhaust or properly fitted performance exhaust ?
I've replaced plugs, coils,bots,Thottle postion sensor, Fuel filter, upstream o2 sensors, New air filter and Cleaned MAF sensor. old plugs were not wet with oil or ant freeze, Air filter in great shape, it starts and ildes perfectly, it's just after driving for a while it will start to hesitate ,then smoothes out,has good pick up otherwise but it happens on and off, then the E light comes on and the codes i get,P0513,P1152 &P1132, used Lucas cleaner,,now oil has slight gas smell,I'm stumped.
try to connect the vacuum / pressure gauge to a good intake manifold source of vacuum hose like pcv valve hose or brake booster , then rev the engine to 2500 rpm, watch the vacuum reading over time.. A known good vacuum would stay around 20-23 Hg of vacuum, without any excessive back pressure in the exhaust... If the exhaust was clogged and had alot of backpressure... the readings would slowy drop from 20-23 to 5-10 Hg of vacuum over time ...I will make a video soon to show it
does no more then 2 psi apply to all gas vehicle engines? ive got a 03 ram with the 5.7 hemi giving me a cat code,id like to check the cat this way to see if its bad. can i place the test gauge anywhere before the cat?
I have one of those compound meters (vacuum/fuel pressure) and I plugged it into my DPFE hose to the EGR tube. LOL mine bounces back and forth from 20psi to 5lbs like a spastic tuna.
Hey Danner, nice video I never thought you could check the EGR valve port for back pressure now I'm glad to know that. I'm curious what part of the exhaust causes the back pressure is it in the exhaust manifold? because right out the exhaust manifold is the EGR pipe that goes to the EGR valve. I ask because I'm wondering if a bad or plugged CAT Converter can cause back pressure. Oh and what does a driveability tech mean? thanks
Great job! where do we find experienced auto techs like you~? any suggestions would greatly be appreciated by all that veiw your very imformative vidioe~other than Ford dealers. PepBoys, Good year ,maybe ? thanks. I have 1998 5.4L Expedtion and having hesitaion problems, i'm at a standstill trouble shooting~
Hey Paul I have a GM 5-wire linear egr in my 2.2L 98 s10. I'm getting code p0404. When I try to command (using OTC Genisys) the EGR to open it does not respond to the commands. When I manually depress the pintle I can see the % increase and decrease on the scanner. I have good 5V ref, the pintle position sensor is obviously working and both grounds are good. The problem is that im not getting 12V on the remaining wire. Should I be getting a constant 12V or only when commanded (100% duty cycle)?
Would that test be suitable for turbocharged engines? I think that I've melted my catalytic converter (overfueling due to a damaged fuel injector which was replaced) and now it probably prevents the tubine to spin and create boost. The turbine is checked and ok.
Based on your experience, do you have a clue as to what causes my car to die? This is a 1990 Volvo 760 GLE 2800cc EFI B280F V6 engine with ~240,000 miles. I can start it up from cold, but once I place it in drive, the engine runs rough and dies. Once it dies it is very hard to restart. I have to wait for about 45 minutes. On pulling the plugs, all tips have a black coating indicating that it is running rich. I have installed new plug wires. Also removed the only O2 sensor at the CAT to check backpressure, which is zero PSI at idle and 3000 RPM. I have not checked the fuel pressure. I have to leave this to a profesional. My assumption is that fuel pressure should remain constant at the point where the car runs rough and dies. Removing the Fuel Pressure Regulator vacuum line at idle after operation for 15 minutes did not show any fuel leak. My only other hunch is that the engine may be loosing spark under load!
That other code is a P0153,slow response bank 2 sensor 1 . How hard would the remedy to this problem be determined by a mechanic like yourself~ A few of these reapirs i could do myself, Head gasket no! and timing chain, which i'm hoping it's neither, on a tight budget. other's like the MAF I have no way to ck it, just replace it, and Leaking injectors if i knew which one i surely would do those. Thanks for the info ,good stuff! Who would you recommend,Pepboys or dealer ? Ford dealer $80 to ck.
Hi danner, I've got an escape which has rough idle no screeching noises. No codes typical P1000, WOT on test drive my bank 1 is lean and 50mv and bank 2 is rich 800mv. I'm suspect on plugged exhaust cause of lack of power. Does a plugged exhaust give you lean or rich o2 voltages? Appreciate any help !
MAP should follow TPS, with a plugged cat the MAP sensor wont. The most important part about this are your fuel trims. With a plugged cat, doing this test your fuel trims should be normal. If you have an email address handy I might have saved a before and after shot on my scanner at work. If I did I could send it over so you could see it.
Can I ask you a question?2004 kia sedona lx. when making left turn or nu turns it is hard to do. Is that a bad axel or wheel bearing? Thank U For the Help
Hi, not sure if you can help but I was just wondering what your thoughts are on this sound I’m experiencing with my Jeep? I have a Jeep Commander 5.7 Hemi 2006 with a Magnaflow 49709 cat (newly installed) and a magnaflow 18″ oval muffler (installed a year or so ago) with stock resonator and pipes between the mufflers and cat. I have new sparks and coil packs and have very recently cleaned the throttle body. Nothing appears loose underneath. I have a sound issue from the exhaust, it sounds like a flutter/ chug at the end of the rev range (need to listen carefully). It does not give a smooth rev the whole way through it. Really annoyingly, I cannot remember if I was experiencing this sound before the cat or spark plugs were added or not. Have you got any idea as to what might be causing it? Could it be the stock rear resonator as it appears big and bulky, reducing flow and causing some sort of back draft sound/ issue?. Thanks for any help! ua-cam.com/video/y1ELsi7ZDT0/v-deo.html
My other response got set as spam. Weird. But no its not intermittent. Code is sent after a few miles of driving after I clear the code every time. I put battery voltage on the control wire with test light and it lit up. So it looks like my control wire is shorted to ground. I figure that's the reason by the pcm cant command the egr to open?
my dpfe hose disintegrated the same way the one in the video did. it looked like fuel line so I replaced it with a piece of fuel line I had laying around. Is that okay or is it going to melt and catch on fire or something haha.
The best site on UA-cam for diy auto repair, because he is a teacher first, mechanic second.
Thank you!
Every time I see ScannerDanners vids I learn something new. Bought his e-book and it was worth every penny!
Pro trick : you can watch series at flixzone. I've been using them for watching loads of movies these days.
@Zion Erick Yup, I have been using flixzone for since december myself :D
@Zion Erick yup, I have been using Flixzone for since december myself :)
I bought his paper version, it has already been worth the money. I came across his videos by accident, I am very impressed. I bought the book just after. I would recommend the book and the videos to all ages and levels of experienced techs.
An oldie but a goldie. 👍🏼
It certainly couldn't hurt to do the test and as you said you would want to measure each side, unless it has an EGR system that would enable testing at that location.
If it is normal at the EGR then checking each side wouldn't be necessary. If it is higher than normal then you would have to figure out which side is restricted.
One thing to note, on a car old enough to possibly be having a clogged exhaust issue. Many times the tiny passages going to the transducer or DPFE / EGR can become clogged. Although it is a different problem, it can prevent testing from these locations accurately.
Invaluable videos and ideas. I have also seen that intake vacuum drops as exhaust back pressure builds.
Yes and remember this is a no load 3000 rpm in park test.
ever test back pressure full load wot? i’ve tried for fun on my stock s2000 with high flow cat, I get 2psi back pressure before and after cat. then I tried on gfs rsx type s all stock, get about 8psi before cat, 2psi after cat. these are done wot hitting close to 8000rpm. just wondering if that’s normal. I get almost no back pressure under no load holding 3000rpm
Thank you for the recommendation for the Ford engines. Much more painless than getting to the front o2 on a 4.6. I previously tried the brake booster hose on a vacuum gauge and that didn't seem to provide accurate results. Will definitely try the DPFE method on my 99 Mustang GT.
Man your Awesome!! I just wanted to tell you thanks man I have a 98 crown vic police interceptor and i was going to have real trouble getting at the O2 sensor to do a back flow test and you showed that alternative way to check it! Thanks man your Videos are great and I always enjoy learning from you videos !!!
Very good way to check a problem with a plugged exhaust
I had this problem with my old bronco II.t. Turns out an intermittent misfire issue I had days prior sent enough raw fuel down stream to melt the catalytic converter. Pulling the EGR exhaust tube and hearing it making a loud hissing noise confirmed the clogged exhuast. Gutting the cat, made fore a quick solution. Thats why I like OBD-1 no trouble codes for doing that!
Well that is a big difference for sure as this is a pintle position open code. Do me a favor, bolt the EGR back on. Take a reading on the signal wire with the engine off, then start the truck and give me another reading. It should not increase in voltage. If it does, you most likely bolted the EGR valve on backwards and vacuum is pulling the pintle open at idle. It can be done, I have seen it, however not all models have the clearance to bolt it on backwards but some do.
@ncrdisabled yes, it is melted and blocks the flow of exhaust gas through it. Also there is a cause of the cat. melting. It is never good to just change the cat. without finding out why it overheated. (misfiring, air/fuel problems etc.)
What about using this pressure gauge to measure the pressure after the cat. On the first test you obviously notice there was excessive back pressure, but you could not determine if it was from the cat or possibly the muffler (collapsed internally causing blockage). If you use the bung hole for the aft O2 sensor (yes sounds funny, but technically correct), the one aft of the cat, you could compare it to the reading forward of the cat. If the second is high, it is caused most likely by the muffler and if lower then the catalytic converter.
@contagiousFX Hey thanks for the comment. I am not sure about the snap throttle vacuum test. (I'll have to do more of them) I know John Thorton (awesome instructor, look him up) uses the MAP sensor signal for his plugged exhaust tests. But I know for a fact that the test where you hold the engine at 3000 and make sure vac. doesn't drop is not 100% accurate. I had a car with 5 psi of back pressure pass that test with flying colors.
looks like this is a good test to check for egr valve activity also
@Mrgeemoney25 That works but only for severe restrictions. I have had car with 5 psi of back pressure at 3000 RPM like in this video that passed that vacuum test with no problem at all. Thanks for the heads up though. I think the vacuum test is only 100% when you do snap throttle testing. I'm just not real confident with the test results on that yet.
I've seen partially plugged cats. pass the vacuum test, so I haven't tried to use it since.
BTW I like a .8 of a volt closed valve position, just make sure it stays there at idle. The pintle should be facing the intake port NOT the exhaust port. In other words intake vacuum should be pulling the pintle down, not up. This also backs up the notion that it cannot be a plugged exhaust causing this as exhaust gas pushes against the pintle on the back side.
I just break out a drill bit and drill a thick spot of metal for a 1/4" pipe thread on the exhaust then tapping it put in a fitting then test it. When done you just put a 1/4" plug in and your done. Time to do is about 15 minutes.
Don't worry about the bi-directional control not working. What is EVP voltage KOEO and what is EVP voltage at idle? If the voltage rises significantly from KOEO to KOER then you most likely bolted the EGR valve on backwards and vacuum is pulling it open slightly. If voltage is high both times then most likely carbon on the seat and stem area is holding the valve open a little
Thanks for your video, need to check my Back Pressure in the near future.
Don't feel bad Paul, I've ripped the hoses off like that and broke some very weakened plastic nipples off the DPFE.
Those parts see a lot of stress from the engine bay heat and exhaust gas heat.
Not Ford's best idea.
Thanks for showing known good then bad
Either one, I used to work for Pep Boys. But you have to find a store with a good driveability tech. the other stores in my area would send their "problem cars" to me. so it is kind of hit and miss. Same way at the dealer.
Thank you Jeremy!
Wow, great info. I suspect a plugged cat on a buddys 4.6 f150 and am going to measure the back pressure at the egr tomorrow. Thanks for the usefull info!
@drm315 Yea, I thought that was interesting too. I really don't have an answer for that, it definitely could be a venturi effect. I don't think it was the gauge, I think it was actually a vacuum.
There is. Doing drive ability I always road test to verify the customer complaint. I always do this test during the road test, not in the bay. Drive the car till you get to where you feel a lack of power. From there move the throttle past where you are and back to that point again a bunch of times and watch the MAP sensors response.
Thanks man appreciate it very much
Thank you!
My bad, its a p0404 code. According to GM service manual, code is set off when there is more than a 10% difference between the desired and actual position. Getting good ground and I tested the reference and power voltage and both come out good at 5 and 12 V respectively. I removed EGR and checked the voltage on the EVP and was getting about 0.8V with the pintle at rest and about 4.4V fully depressed. Smooth voltage change as I manipulated the pintle. Dont have a scan tool so I just used a DVOM.
not sure why gm changed it. but i assume it is for some type of circuit monitoring. nice job finding that fault!
Excellent testing on exhaust
Pressure testing.
About 15 yrs ago lbwas at a garage checking the electrics on a wagon, a fitter in the nexted bay had put a new exhaust flexy. On the exhaust system of a wagon, he started the wagon up.and was revving the engine, there was a massive
Bang and he switched off the engine, l walked over to see what had happened,
The exhaust flexy pipe had
Burst open, you could put,
Your fist in the hole, and he said that what happened to the original one that was on,
I then said, you mean to stand there and tell me that,
Did you not think of doing a pressure check on the exhaust system, those flexy
Pipes are over 800 dollars
Each.
Don't think he knows what he is doing.
More expense at somebody's in experience.
solved the problem. the control wire connection to the egr valve was hanging on by onky a few threads. the connection was hidden behind that rubber insert gm has behind the connector. you are right it was power side switch. why does the ground need to go to pcm as well?
Is there are standard you are using, when watching those two PIDS? I am certainly open to learning too my friend.
great video. i come away from your videos knowing more and more about cars. thanks for the informative videos.
Thanks for the reply. I was aware I might get codes with the new exhaust system, and I did eventually. But it does feel like it doesn't have the power it used to have, so when I first came across one of your exhaust pressure videos I thought it might be worth a shot checking to see if the cats did get overheated. There was a few misfire codes a year ago very briefly, but I think the code was for the coil pack. I don't know if this is the type of misfire that can hurt a cat or not.
Thanks for the comment and support!
"If it breaks it needed replacing anyway" ~ Murphy's Law, 1982
As always good stuff ,and i like it when keep it real ...thx
Perfect!!! That's all i can say. Maybe i'll try and sneak in this test next time.
The P0405 is described as "Pintle Position Circuit Low Voltage". A plugged exhaust would not set this code. You potentially have a wiring problem. What is the EVP signal wire voltage with the KOEO (key on engine off)? What does the scan tool show EVP voltage and % at also KOEO?
Great video. Thanks
@turbobuick33 The first gauge in the video appears to be an OTC 7215 exhaust gauge. It has the same look and stainless steel braided line. See Tool Topia for a pic of if.
P1152 and P1132 is "lack of O2 switch, sensor indicates rich" and this is on both banks. So this suggests not an O2 problem but a rich running condition. (that matches your gas smelling oil too doesn't it?) there are a lot of different cause of rich conditions. fuel psi too high, fuel psi reg leaking (return type only), faulty MAF sensor, ECT sensor reading too cold, leaking injectors, bad head gasket, EVAP purge valve issues, timing chain issues, also I don't list a P0513 code? r u sure on that
Good job
I think you can also attach it to pcv valve port on the mainfold right 😊
if the control wire is shorted to ground that EGR solenoid would be energized all the time (on a ground side switched design) and open all the time. you never mentioned a rough idle which is what it would do. some of these were power side switched and with that design BOTH solenoid wires go to the PCM and one will have a constant ground.
Yea, I left it in there on purpose, things don't always go as planned :)
YOU ARE THE MAN
That sounds normal. Does the code set immediately or is it intermittent.
I also have a dodge ram 05 with the 5.7L. Its throwing codes for both cats and some 02 sensors, but only occasionally. I wanted to perform this test on it anyways, but I was curious about the differences for vehicles with 2 cyl banks compared to 1, if any. For instance, I have long tube headers and high-flow cats, but they merge into a y-pipe after the cats and then into the muffler and exit out the same side. Should I take measurements at each of the 4 02 bungs? Should I start with the EGR?
The intake would leak coolant into the oil. Damage the rod & main bearings.
I have been watching threw your videos. Lots of good stuff going on. With this one I was curious if you had experimented with engine vacuum, either vacuum gauge or MAP pids and TPS, to show a plugged cat?
what have you done to it? are there any trouble codes?
Guy I used to work with would drill a small hole in the exhaust to test back pressure and then weld it back up when he was done. Not the way I would do it, but effective.
On your test on the G6 the gauge seemed to go to vacuum when raising the rpm. Is this a venturi effect or just the gauge bouncing?
Great videos! Look forward to the next one.
you are a beast.. thank you sir. good video..
Oh, ok. Did the cars with partially plugged cats have a drive ability problem related to the cat? or multiple issues?. I am just curious. I ran into an older Mercedes that had no easy access to back pressure testing but had all the symptoms of a plugged cat, and possibly more. The customer didn't want to spend any money on the car so I had to stop before I got a good chance to play with a vacuum gauge... All though I have had lots of success using MAP and TPS pid data on other cars.
If you have no low power complaints then I wouldn't worry about a backpressure test. This is not the test that is needed for a cat. code. In most cases the cat. code shows up way before it gets to the point of restricting the exhaust. My guess is your "high flow" aftermarket cats is what is setting the cat. codes. I'm afraid the only fix for that is to put the factory ones back on. I have ZERO luck with aftermarket cats. They just don't meet the OEM standards.
im doing a back pressure test on a 2004 dodge dakota and the gauge is bouncing from negative vacuum to 1 psi at idle. any ideas ?
Exhaust valve issue is my guess. The negative might mean it's partially open when it shouldn't be
Good video!!! What are you thoughts concerning a standard exhaust vs a performance exhaust. Which exhaust is better for the engine a properly fitted standard exhaust or properly fitted performance exhaust ?
I've replaced plugs, coils,bots,Thottle postion sensor, Fuel filter, upstream o2 sensors, New air filter and Cleaned MAF sensor. old plugs were not wet with oil or ant freeze, Air filter in great shape, it starts and ildes perfectly, it's just after driving for a while it will start to hesitate ,then smoothes out,has good pick up otherwise but it happens on and off, then the E light comes on and the codes i get,P0513,P1152 &P1132, used Lucas cleaner,,now oil has slight gas smell,I'm stumped.
try to connect the vacuum / pressure gauge to a good intake manifold source of vacuum hose like pcv valve hose or brake booster , then rev the engine to 2500 rpm, watch the vacuum reading over time.. A known good vacuum would stay around 20-23 Hg of vacuum, without any excessive back pressure in the exhaust... If the exhaust was clogged and had alot of backpressure... the readings would slowy drop from 20-23 to 5-10 Hg of vacuum over time ...I will make a video soon to show it
does no more then 2 psi apply to all gas vehicle engines? ive got a 03 ram with the 5.7 hemi giving me a cat code,id like to check the cat this way to see if its bad. can i place the test gauge anywhere before the cat?
I have one of those compound meters (vacuum/fuel pressure) and I plugged it into my DPFE hose to the EGR tube. LOL mine bounces back and forth from 20psi to 5lbs like a spastic tuna.
"Snaps" I learned in high school auto shop class from my instructor are also known as "Italian tune ups."
@Username64870 Thank you friend
Hey Danner, nice video I never thought you could check the EGR valve port for back pressure now I'm glad to know that. I'm curious what part of the exhaust causes the back pressure is it in the exhaust manifold? because right out the exhaust manifold is the EGR pipe that goes to the EGR valve. I ask because I'm wondering if a bad or plugged CAT Converter can cause back pressure. Oh and what does a driveability tech mean? thanks
Thank you
Great job! where do we find experienced auto techs like you~? any suggestions would greatly be appreciated by all that veiw your very imformative vidioe~other than Ford dealers. PepBoys, Good year ,maybe ? thanks. I have 1998 5.4L Expedtion and having hesitaion problems, i'm at a standstill trouble shooting~
Would a bad exhaust valve cause additional pressure?
Nice!
getting 0.75 volt koeo and at idle. egr only bolts on one way and is a brand new unit. no carbon build up.
What should we do with the removed O2 sensor? Shouldn't we find a way to remove all oxygen from its nose?
It was from our tool room at school so I am not sure, sorry
Hey Paul I have a GM 5-wire linear egr in my 2.2L 98 s10. I'm getting code p0404. When I try to command (using OTC Genisys) the EGR to open it does not respond to the commands. When I manually depress the pintle I can see the % increase and decrease on the scanner. I have good 5V ref, the pintle position sensor is obviously working and both grounds are good. The problem is that im not getting 12V on the remaining wire. Should I be getting a constant 12V or only when commanded (100% duty cycle)?
Would that test be suitable for turbocharged engines? I think that I've melted my catalytic converter (overfueling due to a damaged fuel injector which was replaced) and now it probably prevents the tubine to spin and create boost. The turbine is checked and ok.
Based on your experience, do you have a clue as to what causes my car to die? This is a 1990 Volvo 760 GLE 2800cc EFI B280F V6 engine with ~240,000 miles. I can start it up from cold, but once I place it in drive, the engine runs rough and dies. Once it dies it is very hard to restart. I have to wait for about 45 minutes. On pulling the plugs, all tips have a black coating indicating that it is running rich. I have installed new plug wires. Also removed the only O2 sensor at the CAT to check backpressure, which is zero PSI at idle and 3000 RPM. I have not checked the fuel pressure. I have to leave this to a profesional. My assumption is that fuel pressure should remain constant at the point where the car runs rough and dies. Removing the Fuel Pressure Regulator vacuum line at idle after operation for 15 minutes did not show any fuel leak. My only other hunch is that the engine may be loosing spark under load!
Is the NOx upstream the same as O2 upstream? I’m working on medium duty diesel vehicle and I want to check back pressure!
Scanner Danner you da boss
Where did you buy that exhaust pressure gauge with the fittings at?
Awesome tip, thanks
That other code is a P0153,slow response bank 2 sensor 1 . How hard would the remedy to this problem be determined by a mechanic like yourself~ A few of these reapirs i could do myself, Head gasket no! and timing chain, which i'm hoping it's neither, on a tight budget. other's like the MAF I have no way to ck it, just replace it, and Leaking injectors if i knew which one i surely would do those. Thanks for the info ,good stuff! Who would you recommend,Pepboys or dealer ? Ford dealer $80 to ck.
Good job friend
Hi danner, I've got an escape which has rough idle no screeching noises. No codes typical P1000, WOT on test drive my bank 1 is lean and 50mv and bank 2 is rich 800mv. I'm suspect on plugged exhaust cause of lack of power. Does a plugged exhaust give you lean or rich o2 voltages? Appreciate any help !
MAP should follow TPS, with a plugged cat the MAP sensor wont. The most important part about this are your fuel trims. With a plugged cat, doing this test your fuel trims should be normal. If you have an email address handy I might have saved a before and after shot on my scanner at work. If I did I could send it over so you could see it.
Can I ask you a question?2004 kia sedona lx. when making left turn or nu turns it is hard to do. Is that a bad axel or wheel bearing? Thank U For the Help
Hi, not sure if you can help but I was just wondering what your thoughts are on this sound I’m experiencing with my Jeep? I have a Jeep Commander 5.7 Hemi 2006 with a Magnaflow 49709 cat (newly installed) and a magnaflow 18″ oval muffler (installed a year or so ago) with stock resonator and pipes between the mufflers and cat. I have new sparks and coil packs and have very recently cleaned the throttle body. Nothing appears loose underneath.
I have a sound issue from the exhaust, it sounds like a flutter/ chug at the end of the rev range (need to listen carefully). It does not give a smooth rev the whole way through it. Really annoyingly, I cannot remember if I was experiencing this sound before the cat or spark plugs were added or not.
Have you got any idea as to what might be causing it? Could it be the stock rear resonator as it appears big and bulky, reducing flow and causing some sort of back draft sound/ issue?. Thanks for any help!
ua-cam.com/video/y1ELsi7ZDT0/v-deo.html
would a compression tester work for this on the dpfe sensor? i have a lincoln navi and mine is on the side of the upper intake. Thanks!
had my dying when you ripped the hose lmao thanks for the laugh thumbs up
haha thanks bro
What if you dont have any back pressure, how would it effect the car. What if i put an exhaust cut outs after the catalytic converter.
My other response got set as spam. Weird. But no its not intermittent. Code is sent after a few miles of driving after I clear the code every time. I put battery voltage on the control wire with test light and it lit up. So it looks like my control wire is shorted to ground. I figure that's the reason by the pcm cant command the egr to open?
You can hear its plugged in the exhaust note at high rpm....
What causes the back presser problems is it the cat converter ?
if your upstream is "0" idle and 2.5 no change,should you even test downstream
If that cat was plugged it probably pop that hose like you did lol
my dpfe hose disintegrated the same way the one in the video did. it looked like fuel line so I replaced it with a piece of fuel line I had laying around. Is that okay or is it going to melt and catch on fire or something haha.
blosom2315 It is normally a silicone based hose
nice