8 YEARS AGO! You sir, are a shining light to people like myself! An old electro mechanical engineer... 2 million views? Fabulous teaching! Greetings from NZ
By far you are the best channel for learning auto systems. your explanations are simple and clear. thank you so much. also great sense of humour every so often.
After years your videos still educational videos you teach me easy tricks to test a sensor without wiring diagram that's amazing bro... Thanks sooooo much
So very well explained. Really good. But please note that that MAP sensor is good. It increases the voltage only during acceleration. So if you are doing constant 20MPH it will be 1/1.5 depending on car make - it will go us as son as you decide to go from 30 to 60 and will stay up untill you reach 60 and release the pedal slightly (vacum if you have a vacum meter - many call it economy metres - goes down and Absolulte Pressure returns to normal) and the fuel mixture changes to lean again. At 60 MPH it changes according to the reading of the MAS Airflow Sensor. Anyway - the industry needs more people like you Well done again.
I am not sure I understand your question. 1. Anything simple that can cause a map sensor fault is. The map sensor is located in the inlet manifold after the air filter - it can get dirty / contaminated especially if you remove the air filter and use a gause filter or a filter which is not so good at filtering the air. Very easy to remove and clean. Many videos on U tube - only one screw maximum 2. It is vey reliable but its an electronic part and does not really like engine vibraions - and the engine heat. So it depends which car. On my car it has 153 K miles and never chaned. On my wife car it was changed after 163 K miles. 2. fault that can be easily checked without buying a new map? I would say that anyone that wants to test the electrinc sensors of his car himself, apart from the fact that deciding which sensor, if any, is the core of any issue to sart with; he should buy a Code Reader also called a Scan tool since it scans/checks all the sensor. Thanks to mass prodyctin these are ridiculously cheap - 24 Dollars sometimes even less from the shop than from Amazon. Googel - "car cheap code readers" or Go here: www.google.com/search?q=cheap+engine+code+tester&oq=cheap+engine+code+tester+&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTIxMDM5ajBqN6gCALACAA&sourceid=chrome&ie=UTF-8 i@@arniet1
I'm a long time, automotive DIYer and am getting into doing light automotive repair and service side work. I'be watched a few of your films along with DIY Auto Tech and Scanner Danner to help me improve my diagnostic skills instead of just being a parts changer. You have another subscriber, Amigo. Keep up the great work!
The map sensor is fine, when you crack the throttle slowly, the engine spins up, but the throttle does not open further. That causes more vacuum to form inside the intake, typically the map will read about the same as at idle or lower (since the pressure is usually lower). Otherwise cool video!
You are definitely the man . at 72 years young I understood everything you were testing .. My VW 2.5 TDI 2001 199,000 miles has gradually lost pulling power .I replaced the old original exhaust with a nice new Stainless de cat system .It was marginally more responsive , but after fitting a pressure gauge to the intercooler housing the measured boost topped out at 11 psi. I was told to expect up to 18psi. The MAF sensor was replaced for testing only and the difference was unbelievable the turbo boost increased as before but then continued to increase easily passing the 1 bar pressure gauge I had plumbed in . now all I need to do is attempt to clean the original MAF sensor and see if it was recoverable . my short journey transport is a 2011 Nissan LEAF . Everyone should have one of those .. they are the future.
Another beautiful explanation. Especially that the IAT sensor is in the MAF in the newer cars. I like your deep knowledge and precise explanations. RECOMMENDED!
I do like your videos. Myself, I find some of them boring but I've been working on cars for over 30yrs, but for a novice these are great! Not too much technical detail for them to lose interest, just enough to keep their attention and teach them how to fix their vehicle!
U r really good.....I just saw another video by an automotive engineer. Combined with ur video, everything fell easily in place. The engineering info with a knowledgeable technician’s experience.....is the best tutorial.....thanks
There is one think I need add for the less knowledgeable/experienced. Identify the fixed supply voltage first using Volts setting. No damage can be done while testing any pin for volts. HOWEVER ONCE YOU CHANGE TO OHMS, to identify the ground wire, you MUST make sure that you NEVER touch the Supply Voltage Pins again. Under OHMS , the meter will short the supply voltage to earth, blow a fuse which might not blow fast enough and you could cause damage to the electronics, So be warned. You either do it in full conformance with how this man described it or you could do more harm than good.
super clear.... great video.... thanks a lot!!!! i just got my new OBDII scanner and with this video I hope I can fix my kids car.... next...THE WORLD!!!!!!
RnW, Big question for ya. I need some help from you or the group. I am working on a 2003 Audi TT quattro. She threw a handful of codes that lead me to believe that there is one (maybe 2) sources causing the codes versus 5 to 6 actual failed components. The codes are; P0031, P0037, and P0141 all pertaining to Oxygen sensor heaters. I tested the sensors and they tested good and in fact are not getting 12v from the ECU. THe next series of codes are P0445, P0449 and P2401 all pertaining to the EVAP system valves and leak detection pump, I have not tested any of these yet. There is a P0414 and P0418 for the AIR system switching and control, the blower is working properly, I have not yet checked what the voltage is that it is receiving yet. The one that I am hovering around is the P0102 Mass air flow sensor "A" circuit low. All of the codes are referring to either a short or low circuit, when I tested the MAF sensor the voltage with the ignition off was sitting at 1.49vdc and when started it was all over the place and never settled anywhere and would dip as low as .004 vdc and barely make it over 1.0vdc. I think I gave as much info as I can at the moment. Let me know what I should do from here so I don't start throwing parts at it.
After many, many hours/days/weekends of troubleshooting this problem I found the source. Fuse #43, marked "engine,petrol". It is hard to admit to such a simple fix for this but that was it. I noted that all of the failed components (indicated by trouble codes) all had a common wire "blue w/ yellow stripe", traced them on the schematic and shot it back to the relay, then the fuse.
big question for you. I need some help from you my vehicle start ok but when u attempts to accelerate it cuts off, I try to start it again it start and when I try to accelerate it cut off, it keeps going like that all the time
Sir tnx for showing us how to test a sensor using a voltmeter most of us newbie mechanic can't afford to buy a high end instrument tnx for all the info sir subcriber from the Philippines
Your MAP sensor was just fine. It measures PRESSURE, not volume. When you open a throttle slowly you barely increasing any pressure but you are increasing the volume which is why it was properly working the way it should.
Step 1. Locate MAP sensor location on your car. Step 2. Reconnect electrical connector to said sensor which had failen off due to the little hooter that holds it in place being broken. Step 3, employ white zip tie to prevent this from happening again, inadvertently. Step 4. Leave nice comment about well taught lessons on MAP and MAF sensors to RnW big guy. Step 5. gloat to your kids how you're now an ace diagnostician. Step 6 sheepishly thank the Lord and RnW for making you learn something without buying a part willy-nilly.
An oscilloscope is about the only reliable way to test a mass airflow. I've seen MANY MAF sensors that looked fine on a scan tool and a multimeter that had tons of glitches when viewed on a scope. Glitches that were far too quick to even hope to see with a meter.
If you wan't to be certain. But good oscilloscopes kind of cost a fortune in contrast to a cheap reliable multi-meter. They also require a lot more proper care.
BUT... a cheap DMM will tell you if the sensor is bad. So, you have a point, but a meter isn't totally useless. BTW, What causes the spikes you mention? Is there active circuitry inside the sensor, or is the hot wire the only component? Just curious if the spikes are due to a compromised connection, in which case it might be easily repairable (solder joint issue?), or is the platinum wire welded, making it irreparable?
Working on Onan generator, EFI, so so helpful to understand these sensors and how to test. The manuals only give resistance parameters out of box, not operational.
Great video, very detailed. What were you using to test for a vacuum leak from the N75 valve when you determined there was no leaks. What should have happened if there was?
now i understand the maf sensor but i have one question is if the pcm give that maf sensor 5 volt to function it and the sensor it self resend voltage to the pcm by ground wire ( what the function of 12 volt wire?? ) sorry for that question but im still beginner and English is not my native language
I have a 1992 accord that vibrates at idle. I have replaced the IACV, EGR, spark plugs wires, new distributor, cap and rotor, motor mounts all 4 new, clutch damper, power steering pump, and rack, alternator, battery...everything! The tachometer is never bouncing and always very steady and right where it needs to be. I can't find any vacuum hose leaks. New fuel injectors, pressure regulator, air filter, fuel filter. I DO NOT have a check engine light. My question is this, can a faulty MAP sensor cause the engine to vibrate at idle and not throw any codes nor have an effect on the tachometer? Thanks, Billy
I have a question I have a gmc 5.7 1998 3 wire on mass flow 1 is 5 volts the other 2 go to ground what would be you best thought also when I disconnect mass flow when running nothing happens bod reader says bad mass flow and bad cam sensor I installed new distributor with cam sensor no change aks changed crank sender. Thanks Something else truck keeps fouling 02senser upstream bank 1
On GM Map sensors they will always read 5v from the power wire, so that's nothing. And you unplugged the maf and the ecu didn't respond? Sounds like a red flag to me haha.
I missed the cut off but I really have no questions. You do a great job at explaining the components and circuitry so it's just a matter of getting out there and experimenting for myself. Thanks.
@@bluor3713 2-wire is a resistor and the ECM is looking at the current flowing, whereas a 3-wire is a voltage divider where the ECM is looking at the voltage between two power rails. The advantage of the 2-wire is cost, but at the expense of repeatability with varying voltage rails. (Automotive is notorious for quite a range of voltages. Less than 10 under high load without the engine running, to over 14v once the battery is fully charged.)
Please help, My 2007 Honda fit runs very rough also engine light is on. I had the auto zone staff with their tool scanned it. Its says my car needs a new map sensor. So I bought new $107 map sensor put it in, but the car won't start. It can start only when I unplug the connector. And the engine light still on. Why engine won't start with new map sensor?
Hi .I have a 2010 elantra and a launch 123i scanner. Rough idle , drives ok, but poor gas mileage . O volt reading when opening throttle. Disconnected MAF sensor, idles smooths out. Put sensor back in , now gets volt reading, idles better! Did clean the MAF made no difference. Am going to retest MAF sensor Volts with scanner in a complete drive cycle. What do you suggest now? Thanks
Did you replace the MAP sensor and did it resolve? I have same engine (5SFE 2.2l) with lean condition. (Code 25 sometimes) Idles poorly with sporadic acceleration. Help!
My map sensor went bad and I thought it was the map sensor I just replaced it for ten bux brand-new. Instead of doing all the checking I'm just saying if you want to learn it this is a great channel I like it a lot
I have a question, the ground wire on my map intermittently has no continuity, garage say the wires are all fine. But car occasionally goes to limp mode, could i test the ground by putting it on the engine or does it have to go to ecu ground all the time.
idle control and map sensor and maf and iat sensor what the different and the relation between these sensor every one one you tube said they regulate air flow ( ineed more explanation ???
the quickest way 2 check any sensor in your car at multiple working time is to start your car while the car is running..using a car computer set it on live data if it is avalible on the computer, it will tell you what ever u need 2 know about any sensor live and direct..
Finally resolved the issue. . Did a diagnostics test. It indicated some issue at the throttle body. Strip and cleaned it. Put it back. Problem fixed right away. I was told if it happens again within a week or 2 i need to replace it. Luckily its cheap.
Not trying to cut you down just adding to the video when trouble shooting a map sensor you must check all vacuum lines not just the one leading to map sensor and as you can tell in the video the map sensor works but when you snap the throttle it does create a high enough vacuum pressure to actuate it but it has a leak else where In the system think about it logically that's not a independent vacuum source it shares with many other ports ya know
In the case of a turbo application like the 2004 Audi A4 1.8T when the BOV (in recirculating mode) relief boost pressure back in to the intake, wouldn't the MAF experience flow in the opposite direction?
Will a dirty Mass Air Flow Sensor make the car stall? Also, on my car when I unplugged the MAF, my car shut off. My brother's car is stalling when driving, when I unplugged his MAF, his car still ran. Any ideas? Thanks
If somebody needs the information: it depends from car to car. Remeber: the maf or map sensor is used to calculate the air/fuel ratio. If you habe a broken, durty, ... sensor your engine can have trouble to calculate the right mixture. Old cars dont have as much problems because there tollerance is a lot higher. Like old and new diesel engines. In new cars the engines are so fuel efficient because they are tuned very well. But pefect tuned cars need more love. So some cars will go out, some will go into a emergency programm... it can depend hard. But yes it can make your car stall and stuff. Like in the video you see when he applies hard throttle the sensor "work", but when crussing it wont. With a maf sensor it can also be that you get some "wrong air" after the sensor (when you have a hole in your system where it sucks air into the system after it passes the maf sensor). So the sensor doesnt register all the air what is going into the engine and caluclate the wrong fuel air mixture.
Easiest way for map sensor is to have Key ON engine OFF, this simulates wide open throttle(atmospheric pressure present, no vacuum present with engine off). This should give you your 4.4.5V, or your max pressure reading. Then start car and check at idle and compare to specs. Boosted cars don't apply to that though
tested MAF sensor as described and found voltage did not go up or down with RPM. Got a new MAF sensor and same thing - no voltage change with RPM change. its on a a 2004 buick regla LS. what is the deal? seems like new MAF sensor is bad too or something wrong with test. Thanks for any help!
why did you change the probes in the last test ? you have replaced the N to the Posetive and P to Negative ? also I have a question : I have a scooter Daelim S3 advance 250cc it has a part calls (SENSOR, MAP & AT) for the fuel > and I see another bigger one for the air it calls SENSOR, THROTTLE POSITION : what is this device ??? (they should be two, one for the air and one for the fuel, right ???) : the scooter has ran only 12000 km and now it starts hardly and even after it works and I turn it off , I go to try after 10 seconds and it starts hard again after many tryings and it runs before the battery die.. what do you think sir ? another additional problem : the thermometer arrow goes to the maximum temperature (red level) 10 minutes after the engine runs ???
how do U know that yours readings from dvom is correct,is map or maf have digital or analog signal,if have digital signal U cant read good mesurment because multimeter dont have speed to mesure so fast signal in mili seconds,if I see good that map and maf have digital signal and U read some inacurate voltage and in video we can see how multimeter have late readings on map sensor for that test U need osciloskope because of speed in MS Sorry for my writings if I spell something bad I am from Europe tnx
To the owner who posted this video. May you please answer this question please? Thank you. I've a Ford Ranger 1992 3.0 v6 engine when I turn it on the truck is in park gear but when I press on the brake only the truck revs up when park. Is it a MAP sensor or brake booster issues? I changed the TPS Sensor, oil/transmission changed. Do you what is the problem?
Sir, why one output terminal of my car ignition coil gives less sparks than the other terminal. In fact, the 2 terminals are control by a single primary circuit of the same ignition coil!!! The other ignition coil has the same issue. I have checked for all resistance readings of the PRIMARY AND SECONDARY CIRCUITS of each IGNITION COILS which shows normal values. Please kindly help. Thanks.
What about your coolant systems thermostat? Any chance you have air pockets in the coolant system? Have you recently done any work involving the coolant system (coolant was removed or escaped and you replaced it). what about the radiator fan? Does it work if you isolate the wiring to it by removing the wiring connector and apply power directly from the car battery or a 12-15 volt d.c. supply? Is there a problem with the wiring connector or the wiring harness? Is the radiator fans' relay broken? Test it with a multi meter or if your car has an identical relay for something that can be "sacrificed" momentarily, like the headlights (and you know the headlight relay works because your headlights turn on and off) insert it into the radiators relay position and allow the cooling system to heat up. If the fan activates before the car arrives at the accelerated rate of heating you report, re-install the relays and move onto the coolant or water temperature sensor that measures the coolant after it leaves the radiator or before it re-enters the engine. If this sensor works correctly it sends a signal to the radiator fans relay (which is confirmed as "working") at or very close to the cars intended threshold for operation at the optimum coolant temperature. If that all checks out, have a look at the radiator filler cap. Is it clogged with debris? Is the rubber gasket ok? Does the spring appear to work correctly by consistently returning to its rest position after repeated manual compressioi? Oh--do you have enough coolant in the radiator? Is the overflow tube leading from the radiator cap intact and able to transfer coolant back and forth between the radiator and the overflow tank? I'm scratching the surface of items related to the coolant system and as you've likely sensed, I'm not a mechanic but start with my suggested diagnostic chain and act accordingly. Good luck--hopefully it's something simple, inexpensive to repair--like a wiring harness that's not quite making contact with a wiring connector-just push it together until you hear a click and all should be good--assuming there's only one coolant related problem--never assume there's only one or two problems. When diagnosing anything, assumptions of correct operation of a component that was then currently unconfirmed may form the basis of an incorrect diagnosis and needless costly reaction in terms of parts and labour that will not correct the problem and possibly compound the frustration you likely feel and add confusion of thought to a reasoned process of diagnosis that leaves no room for guessing, wishful thinking, or unconfirmed results in test procedures.
Hacks509 overheating is not a mass air floe sensor issue...coolant level/mixture....water pump, thermostat stuck shut, coolant temp sensor, fan , and even a bad temp gouge itself are related to the operating temp...
I love this. I must learn more. I have been fixing cars for 50 years, but always the older non-computerised cars. Now I have spent a thousand $ on incompetent garages using their computer diagnostics and believing the computer instead of using the very few brain cells the Lord God gave them. From now on I will watch and learn from you.
Evening. i have a non working boost gauge on my 2014 Focus ST, i took it to Ford and they were next to useless diagnosing anything, out of lazyness thet said it was the upper dash gauges, which i was suspicious about, they also wanted $1200 to have them replaced. I left angry and bought instead another used gauge and same issue , it does not move. so that told me the gauge is fine. i am thinking that the issue could be the actual boost sensor/s, would you know the location of these and do you have any thoughts on this issue? any help would be greatly appreciated.
One question when ur engine is runnng and unplugged the maf the engine must to shutoff.? Or not. And what is the engine keep running like rough idle. But u already cleaned the maf. What could be?
Can the MAP sensor cause an intermittent misfire and sometimes shuts off with no check engine light on when it happens. This only happens at idle and not every day 🤔
you do not understand what is going on with map. Manifold absolute pressure. Put a vacuum gage on the manifold vacuum line and notice its when you quickly open the throttle that the pressure drops. Not with a slow opening of throttle.
NebukedNezzer you're right, he's wrong. I nearly replaced a $80 MAP sensor when I had the exact so readings as he had. He has the part about the MAP telling the fuel to open up correct though.
Hi. Good video. I've checked the voltage at the plug from the loom. I've got 4.99V on one, 4.56 on another and zero on the last. Ignition on, engine not running. Is there his correct please? Cheers
MAP sensor detects that driver pressed the pedal to accellerate. from 30 to 50 MPH. Input is always a fixed 5 volts. Yours is 4.99 which is fine just the same. Output should go up from 1 /1.5 volts to max 3or 4 or 4.99 (depending in how hard you accellerate) only during accelleration.from 30 to 50. Once you reach 50 and you release the pedal slightly to stay at 50, the MAP goes back to 1 to 1.5 depending on the car - and fuel mixture becomes less rich. . So in your case your ECU is thinking that you are accelerating all of the time and your fuel consumpltin must be very high. You have to replace that MAP
Thank you I am getting the MAP/MAF code issue so I have no idea what's the deal. The throttle does not seem to open up when I rev the engine. When I start my truck it cranks but turns right off abour 4 to 6 times. Sometimes I give it gas before I crank it and it works. 04 Colorado LS 3.5
Hi I got problem with diesel 2.0 tdi ,no error codes up or check engine light .but hesitate some times as I accelerate .people saying throttle body throttle position sensor canes in turbo clogged up lots different faults 2012 gt tdi each fault tell me about doesn't have the same symptoms and no error code for that fault is evident .obviously I will check the maf sensor like you have demonstrated. But weird thing no code .loses acceleration, just either put foot flat down on gas it picks up mainly if I gear down it works fine picks up speed as normal .also theys switch on accelerator pedal as well . Main thing confused me was no error codes come up .only time error code came up car was shuddering was glow plug light on dash. Other time code think was p0121 the code was for throttle position sensor. Never come up since .car runs perfectly again no codes but odd times does this loss of wont rev passed 2000/2500 revs .just wondering if has rough idea .possibly after car warms up to normal operating temperature. Also another thing said could be coolant temperature sensor 🤔
I have a fluctuating idle on my 2000 Camry since one year, the idle fluctuates between 650 and 480/500, which sometimes causes pressure light to flicker under load. It had the issue when I bought it and still have it. I ruled out IAC, Air Temp sensor, coolant sensor and PCV value. I'm planning to get a MAP from scrapyard and check with that. Anything I might be missing? My car doesn't have O2 sensor in the front like this car has, it has the Resistor Variable instead. I forgot to mention, the idle fluctuates ONLY at operating temperature. It becomes normal for a while, then starts again all over.
2004 vw Jetta 2.0 sedan 1984 CC engine code 2177 lean bank 1 off idle I've changed everything emissions related can you walk me through all possible causes to compare and see if I missed anything. Thanx, for your help!
I have a problem when the outside is cold 8 degrees my Subaru Tribeca difficult start up after a few minute cranking. Is it possible to be from IAT there is 10 degrees difference.
I normally like your videos but on this one you make a very big mistake. MAP remains constant as revs increase because vacuum does not drop as revs increase unless the motor is under load, such as when you rev the motor quickly. You've actually shown a properly functioning MAP sensor.
Actually yes you are correct cause I did the same test and I was wondering is my map sensor bad as well? Then I realize that from the past my vacuum never changed if my vacuum is not changing then no this isn't going to change I knew I wasn't crazy and the only one who saw this LOL
Please forgive my dumbness but I am confused right now! Edit: or wait wait let me explain it as i get it from your comment,, The vacuum remains constant because at idle engine takes the amount of air that it needs and keep the vacuum inside manifold unchanged >> When i accelerate throttle angle opens up more thus letting "calculated amount" of air getting in manifold and then to cylinders so the vacuum still remains unchanged Right? But under load throttle angle changes at Idle so the amount of vacuum decreases? did i understand it right?
The MAP is connected to manifold vacuum. When ever the throttle plate opens up manifold vacuum weakens while ported and venturi gain strength. I think you are all wrong.
hey man..could a map sensor couse a cold start problem..I got mention that my map sensor has the air tempetarure incorporated as well..I have diagnosed no codes for the map only for the o2 heating sensor.many thankx
I have a MAF sensor with four wires I tested all of them but my last one (signal wire) gives me a very low reading 0.05 - 0.12 (when truck running) I even checked that wire for continuanity from the pcm pin back to the MAF connector. Do I just have a bad MAF sensor?
8 YEARS AGO! You sir, are a shining light to people like myself! An old electro mechanical engineer... 2 million views? Fabulous teaching! Greetings from NZ
By far you are the best channel for learning auto systems. your explanations are simple and clear. thank you so much.
also great sense of humour every so often.
Richard May thank you for time and efforts I'm always wanting to learn more .stay blessed
Richard May Q
After years your videos still educational videos you teach me easy tricks to test a sensor without wiring diagram that's amazing bro... Thanks sooooo much
So very well explained. Really good. But please note that that MAP sensor is good. It increases the voltage only during acceleration. So if you are doing constant 20MPH it will be 1/1.5 depending on car make - it will go us as son as you decide to go from 30 to 60 and will stay up untill you reach 60 and release the pedal slightly (vacum if you have a vacum meter - many call it economy metres - goes down and Absolulte Pressure returns to normal) and the fuel mixture changes to lean again. At 60 MPH it changes according to the reading of the MAS Airflow Sensor.
Anyway - the industry needs more people like you Well done again.
Thanks for that info. Is there anything simple that can cause a map sensor fault that can be easily checked without buying a new map?
I am not sure I understand your question. 1. Anything simple that can cause a map sensor fault is. The map sensor is located in the inlet manifold after the air filter - it can get dirty / contaminated especially if you remove the air filter and use a gause filter or a filter which is not so good at filtering the air.
Very easy to remove and clean. Many videos on U tube - only one screw maximum 2.
It is vey reliable but its an electronic part and does not really like engine vibraions - and the engine heat. So it depends which car. On my car it has 153 K miles and never chaned. On my wife car it was changed after 163 K miles.
2. fault that can be easily checked without buying a new map?
I would say that anyone that wants to test the electrinc sensors of his car himself, apart from the fact that deciding which sensor, if any, is the core of any issue to sart with; he should buy a Code Reader also called a Scan tool since it scans/checks all the sensor.
Thanks to mass prodyctin these are ridiculously cheap - 24 Dollars sometimes even less from the shop than from Amazon. Googel - "car cheap code readers" or Go here:
www.google.com/search?q=cheap+engine+code+tester&oq=cheap+engine+code+tester+&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCTIxMDM5ajBqN6gCALACAA&sourceid=chrome&ie=UTF-8
i@@arniet1
I'm a long time, automotive DIYer and am getting into doing light automotive repair and service side work. I'be watched a few of your films along with DIY Auto Tech and Scanner Danner to help me improve my diagnostic skills instead of just being a parts changer. You have another subscriber, Amigo. Keep up the great work!
Been watching your vids for years. You know they're good when I come back and refer to them while on my projects
Great job man! I have searched many videos on various car repairs .You have covered 3 of the problems I have had. You rock bro!!
This video has actually taught me how to distinguish a MAP from a MAF. Many thanks for the lecture.
The map sensor is fine, when you crack the throttle slowly, the engine spins up, but the throttle does not open further. That causes more vacuum to form inside the intake, typically the map will read about the same as at idle or lower (since the pressure is usually lower). Otherwise cool video!
petrol engine , normal ....
Can car have both map & maf?
@@jamesjohnson5700 yes
@TheWindrunner88 ok because I can't tell if my 2019 Hyundai Elantra se has one as in maf
@@jamesjohnson5700 I’m not sure about those, might be able to google it tho
Hey bud I really liked the way you translated this,you made it very understandable because you know your shit. Thanks bud for taking time to share.
You are definitely the man . at 72 years young I understood everything you were testing .. My VW 2.5 TDI 2001 199,000 miles has gradually lost pulling power .I replaced the old original exhaust with a nice new Stainless de cat system .It was marginally more responsive , but after fitting a pressure gauge to the intercooler housing the measured boost topped out at 11 psi. I was told to expect up to 18psi. The MAF sensor was replaced for testing only and the difference was unbelievable the turbo boost increased as before but then continued to increase easily passing the 1 bar pressure gauge I had plumbed in . now all I need to do is attempt to clean the original MAF sensor and see if it was recoverable . my short journey transport is a 2011 Nissan LEAF . Everyone should have one of those .. they are the future.
Can car have both map & maf?
Regarding car repair this is one of the best watched so far......its a truly door opener.....Thank u very much
To reduce vacuum you have to apply load or disconnect the vacuum tube.
That sensor appears to to be working OK.
Yea. He is wrong about the MAP. Bad test. Quick rev response was correct. He interpreted in wrong. MAP was good.
Can a car have MAF, MAP and IAT? Also can you use the same cleaner for all of them?
Another beautiful explanation. Especially that the IAT sensor is in the MAF in the newer cars. I like your deep knowledge and precise explanations.
RECOMMENDED!
I LOVE YOUR AUTO REPAIR LECTURE ! VERY CLEAR EXPLANATION AND TRUELY PRACTICAL ! THANKS LOT FOR YOUR UPLOAD VIDEO !
I do like your videos. Myself, I find some of them boring but I've been working on cars for over 30yrs, but for a novice these are great! Not too much technical detail for them to lose interest, just enough to keep their attention and teach them how to fix their vehicle!
U r really good.....I just saw another video by an automotive engineer. Combined with ur video, everything fell easily in place. The engineering info with a knowledgeable technician’s experience.....is the best tutorial.....thanks
The reason the voltage didn’t go up when you opened the throttle slowly is because you didn’t lose vacuum until you opened the throttle wider
you are a good mechanic u explain with the mechanism how it works also the volt resistance testing failure solution amazing
Bravo ; for 1-fluent spoke
2- fully own and controlling science of this subject.
3- loving your jobs
4- your teaching talent(gifted , from God)
Wow you teach better than anybody I know of. So well, that your accent sounds fluent
There is one think I need add for the less knowledgeable/experienced. Identify the fixed supply voltage first using Volts setting. No damage can be done while testing any pin for volts. HOWEVER ONCE YOU CHANGE TO OHMS, to identify the ground wire, you MUST make sure that you NEVER touch the Supply Voltage Pins again. Under OHMS , the meter will short the supply voltage to earth, blow a fuse which might not blow fast enough and you could cause damage to the electronics, So be warned. You either do it in full conformance with how this man described it or you could do more harm than good.
super clear.... great video.... thanks a lot!!!! i just got my new OBDII scanner and with this video I hope I can fix my kids car.... next...THE WORLD!!!!!!
one of the best mechanics on youtube keep up the goodwork , good videos and always spot on . helps me 100% of the time
RnW, Big question for ya. I need some help from you or the group. I am working on a 2003 Audi TT quattro. She threw a handful of codes that lead me to believe that there is one (maybe 2) sources causing the codes versus 5 to 6 actual failed components. The codes are; P0031, P0037, and P0141 all pertaining to Oxygen sensor heaters. I tested the sensors and they tested good and in fact are not getting 12v from the ECU. THe next series of codes are P0445, P0449 and P2401 all pertaining to the EVAP system valves and leak detection pump, I have not tested any of these yet. There is a P0414 and P0418 for the AIR system switching and control, the blower is working properly, I have not yet checked what the voltage is that it is receiving yet. The one that I am hovering around is the P0102 Mass air flow sensor "A" circuit low. All of the codes are referring to either a short or low circuit, when I tested the MAF sensor the voltage with the ignition off was sitting at 1.49vdc and when started it was all over the place and never settled anywhere and would dip as low as .004 vdc and barely make it over 1.0vdc. I think I gave as much info as I can at the moment. Let me know what I should do from here so I don't start throwing parts at it.
After many, many hours/days/weekends of troubleshooting this problem I found the source. Fuse #43, marked "engine,petrol". It is hard to admit to such a simple fix for this but that was it. I noted that all of the failed components (indicated by trouble codes) all had a common wire "blue w/ yellow stripe", traced them on the schematic and shot it back to the relay, then the fuse.
big question for you. I need some help from you my vehicle start ok but when u attempts to accelerate it cuts off, I try to start it again it start and when I try to accelerate it cut off, it keeps going like that all the time
Sir tnx for showing us how to test a sensor using a voltmeter most of us newbie mechanic can't afford to buy a high end instrument tnx for all the info sir subcriber from the Philippines
Your MAP sensor was just fine. It measures PRESSURE, not volume. When you open a throttle slowly you barely increasing any pressure but you are increasing the volume which is why it was properly working the way it should.
you might be correct sir, gona have to bench test that thing. will update results.
Dev Sam b
he obviously thinks they're the same thing.
bit of a jonny-know-all-wanker.
@@myRatchets So, in the end what was the problem?
Very very good video..appreciate the attention to theory as well as active repair. Shows true reinforcement to problem solving 👍🏼🙌🏼😎
Step 1. Locate MAP sensor location on your car. Step 2. Reconnect electrical connector to said sensor which had failen off due to the little hooter that holds it in place being broken. Step 3, employ white zip tie to prevent this from happening again, inadvertently. Step 4. Leave nice comment about well taught lessons on MAP and MAF sensors to RnW big guy. Step 5. gloat to your kids how you're now an ace diagnostician. Step 6 sheepishly thank the Lord and RnW for making you learn something without buying a part willy-nilly.
I’m on step 4 currently
An oscilloscope is about the only reliable way to test a mass airflow. I've seen MANY MAF sensors that looked fine on a scan tool and a multimeter that had tons of glitches when viewed on a scope. Glitches that were far too quick to even hope to see with a meter.
well said...
If you wan't to be certain. But good oscilloscopes kind of cost a fortune in contrast to a cheap reliable multi-meter. They also require a lot more proper care.
BUT... a cheap DMM will tell you if the sensor is bad. So, you have a point, but a meter isn't totally useless.
BTW, What causes the spikes you mention? Is there active circuitry inside the sensor, or is the hot wire the only component? Just curious if the spikes are due to a compromised connection, in which case it might be easily repairable (solder joint issue?), or is the platinum wire welded, making it irreparable?
sometimes analogue meters are better than dmm's for this type of stuff
Working on Onan generator, EFI, so so helpful to understand these sensors and how to test. The manuals only give resistance parameters out of box, not operational.
In case of MAF sensor, will current be left constant so only the voltage varies with respect to resistance of the hot wire?
Great video, very detailed. What were you using to test for a vacuum leak from the N75 valve when you determined there was no leaks. What should have happened if there was?
What is that spray you're using to look for a Vacuum Leak, around 5:49?
Thank you. Could you please say what you spray the hoses with to check for leaks?
Very practical video for determining baseline characteristics for each of these devices. Thanks very much from the UK.
Forgot to add, thank you for getting to the point and not making me filter out off tangent superfluous crap.
now i understand the maf sensor but i have one question is if the pcm give that maf sensor 5 volt to function it and the sensor it self resend voltage to the pcm by ground wire ( what the function of 12 volt wire?? ) sorry for that question but im still beginner and English is not my native language
This is exactly the video I need right now as I try to fix my car. Almost like if you made it just for me, lol! Thanks a ton for this!
lol nice, glad its useful to you. cheers
What are you using for testing for a vacuum leak? Vacuum won't bubble up under negative pressure.
what were u spaying to check for vacuum leaks, does it suck in what your spraying,is that how you know there is a leak.
I have a 1992 accord that vibrates at idle. I have replaced the IACV, EGR, spark plugs wires, new distributor, cap and rotor, motor mounts all 4 new, clutch damper, power steering pump, and rack, alternator, battery...everything! The tachometer is never bouncing and always very steady and right where it needs to be. I can't find any vacuum hose leaks. New fuel injectors, pressure regulator, air filter, fuel filter. I DO NOT have a check engine light. My question is this, can a faulty MAP sensor cause the engine to vibrate at idle and not throw any codes nor have an effect on the tachometer? Thanks, Billy
I have a question I have a gmc 5.7 1998 3 wire on mass flow 1 is 5 volts the other 2 go to ground what would be you best thought also when I disconnect mass flow when running nothing happens bod reader says bad mass flow and bad cam sensor I installed new distributor with cam sensor no change aks changed crank sender. Thanks
Something else truck keeps fouling 02senser upstream bank 1
On GM Map sensors they will always read 5v from the power wire, so that's nothing. And you unplugged the maf and the ecu didn't respond? Sounds like a red flag to me haha.
Dustin Dykman my hole problem was a bad fuse connection took a week to find it
Very good video. This is the right way to diagnose the fuel injection system.
I missed the cut off but I really have no questions. You do a great job at explaining the components and circuitry so it's just a matter of getting out there and experimenting for myself. Thanks.
No he didn't. He doesn't understand the difference between a 2-wire and a 3-wire sensor.
@@Chris-hx3om what's the difference between a 2-wire vrs 3-wire?
@@bluor3713 2-wire is a resistor and the ECM is looking at the current flowing, whereas a 3-wire is a voltage divider where the ECM is looking at the voltage between two power rails.
The advantage of the 2-wire is cost, but at the expense of repeatability with varying voltage rails. (Automotive is notorious for quite a range of voltages. Less than 10 under high load without the engine running, to over 14v once the battery is fully charged.)
Please help, My 2007 Honda fit runs very rough also engine light is on. I had the auto zone staff with their tool scanned it. Its says my car needs a new map sensor. So I bought new $107 map sensor put it in, but the car won't start. It can start only when I unplug the connector. And the engine light still on. Why engine won't start with new map sensor?
Awesome. Kindly advise me on what tests to carry out on my g16a sidekick engine include TPS, etc
Excellent video and demonstration!Do you have a video for checking vacuum leaks i have a 94 ford f150 5.0 XLT
Hi .I have a 2010 elantra and a launch 123i scanner. Rough idle , drives ok, but poor gas mileage . O volt reading when opening throttle. Disconnected MAF sensor, idles smooths out. Put sensor back in , now gets volt reading, idles better! Did clean the MAF made no difference. Am going to retest MAF sensor Volts with scanner in a complete drive cycle. What do you suggest now? Thanks
Did you replace the MAP sensor and did it resolve? I have same engine (5SFE 2.2l) with lean condition. (Code 25 sometimes) Idles poorly with sporadic acceleration. Help!
My map sensor went bad and I thought it was the map sensor I just replaced it for ten bux brand-new. Instead of doing all the checking I'm just saying if you want to learn it this is a great channel I like it a lot
I have a question, the ground wire on my map intermittently has no continuity, garage say the wires are all fine.
But car occasionally goes to limp mode, could i test the ground by putting it on the engine or does it have to go to ecu ground all the time.
Make sure your engine is grounded in a 'star grounding formation'
@@HomeMadeBoards i decided to make a new ground on the engine block with new wire. Has been working since..
a graphing tool would show any irregularities in the voltage, which is useful for finding intermittent MAF problems
idle control and map sensor and maf and iat sensor what the different and the relation between these sensor every one one you tube said they regulate air flow ( ineed more explanation ???
the quickest way 2 check any sensor in your car at multiple working time is to start your car while the car is running..using a car computer set it on live data if it is avalible on the computer, it will tell you what ever u need 2 know about any sensor live and direct..
Will a dirty MAF sensor have an effect on idling and random engine stalling. I get this issue about every 12 to 18months?
Finally resolved the issue. . Did a diagnostics test. It indicated some issue at the throttle body. Strip and cleaned it. Put it back.
Problem fixed right away.
I was told if it happens again within a week or 2 i need to replace it. Luckily its cheap.
What was the year Mike and model?
Not trying to cut you down just adding to the video when trouble shooting a map sensor you must check all vacuum lines not just the one leading to map sensor and as you can tell in the video the map sensor works but when you snap the throttle it does create a high enough vacuum pressure to actuate it but it has a leak else where In the system think about it logically that's not a independent vacuum source it shares with many other ports ya know
In the case of a turbo application like the 2004 Audi A4 1.8T when the BOV (in recirculating mode) relief boost pressure back in to the intake, wouldn't the MAF experience flow in the opposite direction?
Will a dirty Mass Air Flow Sensor make the car stall? Also, on my car when I unplugged the MAF, my car shut off. My brother's car is stalling when driving, when I unplugged his MAF, his car still ran. Any ideas? Thanks
Tom O did you ever figure it out I’m wondering the same?
If somebody needs the information: it depends from car to car. Remeber: the maf or map sensor is used to calculate the air/fuel ratio. If you habe a broken, durty, ... sensor your engine can have trouble to calculate the right mixture. Old cars dont have as much problems because there tollerance is a lot higher. Like old and new diesel engines. In new cars the engines are so fuel efficient because they are tuned very well. But pefect tuned cars need more love.
So some cars will go out, some will go into a emergency programm... it can depend hard. But yes it can make your car stall and stuff.
Like in the video you see when he applies hard throttle the sensor "work", but when crussing it wont.
With a maf sensor it can also be that you get some "wrong air" after the sensor (when you have a hole in your system where it sucks air into the system after it passes the maf sensor). So the sensor doesnt register all the air what is going into the engine and caluclate the wrong fuel air mixture.
Is there away to repair MAF sensor first before buying a new one like cleaning it first ?
Easiest way for map sensor is to have Key ON engine OFF, this simulates wide open throttle(atmospheric pressure present, no vacuum present with engine off). This should give you your 4.4.5V, or your max pressure reading. Then start car and check at idle and compare to specs. Boosted cars don't apply to that though
man, that's some good info, thanks.
You didn't turn off ignition when testing for continuity
tested MAF sensor as described and found voltage did not go up or down with RPM. Got a new MAF sensor and same thing - no voltage change with RPM change. its on a a 2004 buick regla LS. what is the deal? seems like new MAF sensor is bad too or something wrong with test. Thanks for any help!
Dang 2 Million DiY'ers was helped by this video. Congrats.
why did you change the probes in the last test ? you have replaced the N to the Posetive and P to Negative ?
also I have a question : I have a scooter Daelim S3 advance 250cc it has a part calls (SENSOR, MAP & AT) for the fuel > and I see another bigger one for the air it calls SENSOR, THROTTLE POSITION : what is this device ??? (they should be two, one for the air and one for the fuel, right ???) : the scooter has ran only 12000 km and now it starts hardly and even after it works and I turn it off , I go to try after 10 seconds and it starts hard again after many tryings and it runs before the battery die.. what do you think sir ?
another additional problem : the thermometer arrow goes to the maximum temperature (red level) 10 minutes after the engine runs ???
squirrels ate through MAP wiring in Buick 2009 Allure cxl. Do I need to replace all the wiring? or repair?
Thanks! for this video, easy to understand man. I said hi from Uruapan Michoacán México 👍
how do U know that yours readings from dvom is correct,is map or maf have digital or analog signal,if have digital signal U cant read good mesurment because multimeter dont have speed to mesure so fast signal in mili seconds,if I see good that map and maf have digital signal and U read some inacurate voltage and in video we can see how multimeter have late readings on map sensor for that test U need osciloskope because of speed in MS
Sorry for my writings if I spell something bad I am from Europe tnx
What were you spraying on the vacuum line to test for a leak and how exactly could you tell that there was a leak. Thanks Mike from Maryland
Starter fluid..if there's a leak vacuum will draw it into the engine and cause the engine to surge/accelerate
Cheers. Learned a lot new MAF in 2 minutes!
Hello... I'm Brazilian, see your vídeo very good... congratulation!!
(3:44) Hey, I have one ground and the other two are both high, one 5.1v and other 4.8v , what is going on?
One is constant v other is signal to computer
Signal wire also supposed to have voltage, when sensor not attached?
To the owner who posted this video. May you please answer this question please? Thank you.
I've a Ford Ranger 1992 3.0 v6 engine when I turn it on the truck is in park gear but when I press on the brake only the truck revs up when park. Is it a MAP sensor or brake booster issues? I changed the TPS Sensor, oil/transmission changed. Do you what is the problem?
your explanation is very precise and simple as well. Great job and thanks
Sir, why one output terminal of my car ignition coil gives less sparks than the other terminal. In fact, the 2 terminals are control by a single primary circuit of the same ignition coil!!! The other ignition coil has the same issue.
I have checked for all resistance readings of the PRIMARY AND SECONDARY CIRCUITS of each IGNITION COILS which shows normal values.
Please kindly help.
Thanks.
I have a VW Golf 2.0 1995 and my car over heats quickly and I cleaned the MaF already. any chance i need a new once?
What about your coolant systems thermostat? Any chance you have air pockets in the coolant system? Have you recently done any work involving the coolant system (coolant was removed or escaped and you replaced it). what about the radiator fan? Does it work if you isolate the wiring to it by removing the wiring connector and apply power directly from the car battery or a 12-15 volt d.c. supply? Is there a problem with the wiring connector or the wiring harness? Is the radiator fans' relay broken? Test it with a multi meter or if your car has an identical relay for something that can be "sacrificed" momentarily, like the headlights (and you know the headlight relay works because your headlights turn on and off) insert it into the radiators relay position and allow the cooling system to heat up. If the fan activates before the car arrives at the accelerated rate of heating you report, re-install the relays and move onto the coolant or water temperature sensor that measures the coolant after it leaves the radiator or before it re-enters the engine. If this sensor works correctly it sends a signal to the radiator fans relay (which is confirmed as "working") at or very close to the cars intended threshold for operation at the optimum coolant temperature. If that all checks out, have a look at the radiator filler cap. Is it clogged with debris? Is the rubber gasket ok? Does the spring appear to work correctly by consistently returning to its rest position after repeated manual compressioi? Oh--do you have enough coolant in the radiator? Is the overflow tube leading from the radiator cap intact and able to transfer coolant back and forth between the radiator and the overflow tank? I'm scratching the surface of items related to the coolant system and as you've likely sensed, I'm not a mechanic but start with my suggested diagnostic chain and act accordingly. Good luck--hopefully it's something simple, inexpensive to repair--like a wiring harness that's not quite making contact with a wiring connector-just push it together until you hear a click and all should be good--assuming there's only one coolant related problem--never assume there's only one or two problems. When diagnosing anything, assumptions of correct operation of a component that was then currently unconfirmed may form the basis of an incorrect diagnosis and needless costly reaction in terms of parts and labour that will not correct the problem and possibly compound the frustration you likely feel and add confusion of thought to a reasoned process of diagnosis that leaves no room for guessing, wishful thinking, or unconfirmed results in test procedures.
replace the reservoir cap it could be that
yep....that too.
Hacks509 overheating is not a mass air floe sensor issue...coolant level/mixture....water pump, thermostat stuck shut, coolant temp sensor, fan , and even a bad temp gouge itself are related to the operating temp...
And you could have a bad head gasket...worst case scenario
I love this. I must learn more. I have been fixing cars for 50 years, but always the older non-computerised cars. Now I have spent a thousand $ on incompetent garages using their computer diagnostics and believing the computer instead of using the very few brain cells the Lord God gave them. From now on I will watch and learn from you.
Evening. i have a non working boost gauge on my 2014 Focus ST, i took it to Ford and they were next to useless diagnosing anything, out of lazyness thet said it was the upper dash gauges, which i was suspicious about, they also wanted $1200 to have them replaced. I left angry and bought instead another used gauge and same issue , it does not move. so that told me the gauge is fine.
i am thinking that the issue could be the actual boost sensor/s, would you know the location of these and do you have any thoughts on this issue? any help would be greatly appreciated.
One question when ur engine is runnng and unplugged the maf the engine must to shutoff.? Or not. And what is the engine keep running like rough idle. But u already cleaned the maf. What could be?
How do you do this with cars with DBW? Do you have to physically depress the gas pedal?
Can the MAP sensor cause an intermittent misfire and sometimes shuts off with no check engine light on when it happens. This only happens at idle and not every day 🤔
you do not understand what is going on with map. Manifold absolute pressure. Put a vacuum gage on the manifold vacuum line and notice its when you quickly open the throttle that the pressure drops. Not with a slow opening of throttle.
NebukedNezzer you're right, he's wrong. I nearly replaced a $80 MAP sensor when I had the exact so readings as he had. He has the part about the MAP telling the fuel to open up correct though.
Yes, about the fuel to open. Glad you saved 80 bucks.
NebukedNezzer what's that fluid you used on the vacum line
Hi. Good video. I've checked the voltage at the plug from the loom. I've got 4.99V on one, 4.56 on another and zero on the last. Ignition on, engine not running. Is there his correct please? Cheers
MAP sensor detects that driver pressed the pedal to accellerate. from 30 to 50 MPH. Input is always a fixed 5 volts. Yours is 4.99 which is fine just the same. Output should go up from 1 /1.5 volts to max 3or 4 or 4.99 (depending in how hard you accellerate) only during accelleration.from 30 to 50. Once you reach 50 and you release the pedal slightly to stay at 50, the MAP goes back to 1 to 1.5 depending on the car - and fuel mixture becomes less rich. . So in your case your ECU is thinking that you are accelerating all of the time and your fuel consumpltin must be very high. You have to replace that MAP
So it shouldn't have continuity in the ground and signal wire without any key?
Thank you I am getting the MAP/MAF code issue so I have no idea what's the deal. The throttle does not seem to open up when I rev the engine. When I start my truck it cranks but turns right off abour 4 to 6 times. Sometimes I give it gas before I crank it and it works. 04 Colorado LS 3.5
Hi I got problem with diesel 2.0 tdi ,no error codes up or check engine light .but hesitate some times as I accelerate .people saying throttle body throttle position sensor canes in turbo clogged up lots different faults 2012 gt tdi each fault tell me about doesn't have the same symptoms and no error code for that fault is evident .obviously I will check the maf sensor like you have demonstrated. But weird thing no code .loses acceleration, just either put foot flat down on gas it picks up mainly if I gear down it works fine picks up speed as normal .also theys switch on accelerator pedal as well . Main thing confused me was no error codes come up .only time error code came up car was shuddering was glow plug light on dash. Other time code think was p0121 the code was for throttle position sensor. Never come up since .car runs perfectly again no codes but odd times does this loss of wont rev passed 2000/2500 revs .just wondering if has rough idea .possibly after car warms up to normal operating temperature. Also another thing said could be coolant temperature sensor 🤔
I have a fluctuating idle on my 2000 Camry since one year, the idle fluctuates between 650 and 480/500, which sometimes causes pressure light to flicker under load.
It had the issue when I bought it and still have it. I ruled out IAC, Air Temp sensor, coolant sensor and PCV value. I'm planning to get a MAP from scrapyard and check with that. Anything I might be missing?
My car doesn't have O2 sensor in the front like this car has, it has the Resistor Variable instead.
I forgot to mention, the idle fluctuates ONLY at operating temperature. It becomes normal for a while, then starts again all over.
2004 vw Jetta 2.0 sedan 1984 CC engine code 2177 lean bank 1 off idle I've changed everything emissions related can you walk me through all possible causes to compare and see if I missed anything. Thanx, for your help!
I have a problem when the outside is cold 8 degrees my Subaru Tribeca difficult start up after a few minute cranking. Is it possible to be from IAT there is 10 degrees difference.
after you check it what is it you are looking for? is one or the other one good or bad?
Nice video thanks! my plug is reading 2 constant ground,(mass sensor) e250 2006' whats wrong?
I normally like your videos but on this one you make a very big mistake. MAP remains constant as revs increase because vacuum does not drop as revs increase unless the motor is under load, such as when you rev the motor quickly. You've actually shown a properly functioning MAP sensor.
Very, very good point and kudos to your excellent attention to detail.
Actually yes you are correct cause I did the same test and I was wondering is my map sensor bad as well? Then I realize that from the past my vacuum never changed if my vacuum is not changing then no this isn't going to change I knew I wasn't crazy and the only one who saw this LOL
Interesting
Please forgive my dumbness but I am confused right now! Edit: or wait wait let me explain it as i get it from your comment,, The vacuum remains constant because at idle engine takes the amount of air that it needs and keep the vacuum inside manifold unchanged >> When i accelerate throttle angle opens up more thus letting "calculated amount" of air getting in manifold and then to cylinders so the vacuum still remains unchanged Right? But under load throttle angle changes at Idle so the amount of vacuum decreases? did i understand it right?
The MAP is connected to manifold vacuum. When ever the throttle plate opens up manifold vacuum weakens while ported and venturi gain strength. I think you are all wrong.
hey man..could a map sensor couse a cold start problem..I got mention that my map sensor has the air tempetarure incorporated as well..I have diagnosed no codes for the map only for the o2 heating sensor.many thankx
Very good explanation of MAP and MAF
i just replace map sensor for my hyundai tucson with a new one. but when plugged it the engine stalls. error code is p0170. any idea on this sir?
I'm getting 5v constant on 2 wires, thoughts? Mercedes b200 turbo
Hello. I have 2003 Chvy Trailblazer LS. I cant find the MAF sensor. Please help!
Thank You.
Sir,the back probe should be to the ground and signal or ground and red wire,can you clarify
I have a MAF sensor with four wires I tested all of them but my last one (signal wire) gives me a very low reading 0.05 - 0.12 (when truck running) I even checked that wire for continuanity from the pcm pin back to the MAF connector. Do I just have a bad MAF sensor?