How to test a MAP sensor OFF CAR
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- Опубликовано: 14 апр 2016
- MAP or 'Manifold absolute pressure' sensors are another of the 'family' of electronic sensors used by modern Electronic Fuel Injection systems. The car's computer (ECU) needs to know how much air is entering the engine, together with many other inputs, to calculate fueling and ignition parameters.
Often symptoms like poor starting, excessive fuel consumption, poor emissions and surging can be caused by the ECU receiving an inaccurate signal from the MAP.
Sure, we can use a code reader to see what fault codes (if any) have been recorded but those fault codes only relate to 'circuits' rather than components.
Knowing how to actually bench test this sensor is a far more accurate way of determining if it is working correctly or not. If it is then you can eliminate it from your investigations, if it is faulty then it will need to be replaced, though there may be other faults too so all wires relating to that circuit should also be checked, just in case there may be a short circuit somewhere (insulation has worn through and the wire has grounded) or maybe a break in the circuit too - anything is possible!
In this video I'm checking a MAP sensor from a 1996 Toyota Rav4, its a 3 door version 4wd with a manual gearbox and is fitted with the 3S-FE 2 ltr, 4 cylinder petrol engine. The method of this test does apply to almost all linear voltage type MAP Sensors, however, you will need to source the specification data for your specific Make, model & year of car as the output voltages can vary, especially between manufacturers.
NOTE: This test is NOT suitable for digital output type MAP sensors.
If you have any questions or comments please leave them in the comments section below...
Andy Mechanic! 
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hey bro i have just landed on this video but the wiring order is wrong , u have to switch the ground terminal to the 5v input respectively
Great video. Made it understandable. Cheers!
This is,awesome! I am a lot more comfortable bench testing than dangling paperclips out the connector lol thank you from Colorado, US !
No problem. Pleased you found the video helpful. Andy
If the paperclips accidentally touch each other it can harm the ECU
Hi this is the first video i came across youtube which is actually educational about these map sensors no one really knows or wants to share but you are good man keep it up and i was wondering if all toyota map sensors are wired in this same sequence(+5v,output,ov) thanks.
Buen Video saludos desde México!!
Hello Mexico! Great to have you on the channel. Cheers Andy
Excellent explanation
Cheers from France
Dear sir. Greetings.
Sir. Very good explanation
Very good exp
Demonstration was on point. I have learnt a lot about maf sensor today.
MAP
I need help.my map start at 5.54v with key on(with out start the engine)if I start the engine and give some rpm the voltage go down.Peugeot 106 rallye
I'm in need of a check to show these things about testing map sensor is oxygen sensors mostly also sensors on the 2001 Honda CRV I'm grateful for all your effort God bless you from Felix in New York
just got a remanyfactured engine in my 85 chevy caprice. idles poorly hesitates 10-20mph its throttlebody injected mechanice said i can just swap out tps,iac and map sensor any advice?
Nice video...what is that thing used for vacuum generation? Where I can buy it for cheaper price.
Andy, measuring the signal leg (middle) on the harness of the car I get about 5V but when I connect sensor to the harness and backprobe the signal leg the voltage is at 50mv without any vacuum applied. The voltage supply on the side leg read 5V with and without sensor connected. Do you think the sensor has some sort of short or break? or is it the ECU? thank you!
+biker55555 Hmmmm. ...just check the other two wires as the order may be different on your car. One wire (loom side with sensor disconnected) should be 5v reference, one ground and the 3rd should have no voltage - that will be the signal wire. If all that checks out fine then I'd bench test the sensor.
Hope that helps. Cheers Andy
Hi, very good video thanks, just would like to add that In some cases the map sensor will be off when in a hot or cold condition. I had this with my honda vfr1200 motorcycle. It would run fine for about 200km then start buzzing in my handlebars from the enjine due to to lean fuel calculation & timing combination..
Hi i have 2008 ford focus 1.8 tdci with heavy black smoke under acceleration live data showing 30 psi of boost pressure and mass air flow around 80 g/s around 2500 rpm i thought vnt ring on turbo might have been sticky but it's free , how could i pin point the fault if it is the map ?
Wow am mechanic that actually know show to troubleshoot electronics .... amazin ! As a backyard mechanic ... electronics is my specialty cuz that's what I am trained for as for mechanics ... I'm pretty good there too so now a days you need at the very minimum of basic electronics to deal with todays new electronically techy cars. Before even finding this vid I out of car bench tested my MAP's and both are bad ... sheeesh another trip to the scrap yard.
Hey Andy! love the videos especially your tool girl Sam ones. Umm, I'm a bit confused maybe I got it backwards but at around 9:34 you describe an inverse relationship between vacuum and sensor output voltage as the desired and tested result, but I think either I'm confused a as it is direct relationship (Vacuum up Ev Up) or maybe it was just a slip up. Seems I'm the only one I saw in quick glance at comments who's head is banging so Idunno. Cheers!
+roy mummery Some sensors do inverse, some are proportional. Main issue is you see a steady change in voltage with vacuum.
I too was confused. I thought that this sensor provides feedback to tell the ECU the amount of boost pressure present to maintain the design amount of air/fuel mix to make the 14.5--14.7 to 1. After studying other vids it would seem that the sensor is measuring relative pressure to atmospheric pressure. When the throttle vane is shut the turbo will be slow and the pressure beyond the vane will be low and below atmospheric. The ECU will cut back the fuel via the injection. When the throttle Vane is fully open the Turbo speed is high. The vacuum in the manifold falls back to atmospheric. Now the boost of Turbo takes the pressure in the manifold beyond atmospheric. This is again detected by the MAP and the ECU then sets more fuel into the engine via injection. There comes a point where the boost pressure could be too high( Resulting in Engine damage)and the ECU sends a message to the Vacuum Solenoid valve to dump vacuum on the turbo wastegate actuator so the gate opens to dump turbo exhaust to slow the Turbo down and reduce boost. Now the funny thing is this. Overboost code P0234 can be set with car in 5th going up hill and foot to floor. Also code P1345 also set(Glow plug issue). Limp mode/Engine Warning light set. RPM that this occurs at is around 2,900. Is it possible that the ECU is saying I am labouring the engine and puts it into Limp mode with the Fault codes. Can't be an overboost as turbo is spinning too slowly. I also read that the throttle pedal position is monitored and plays it's part. I have put this info in as the problems one may think they have may not be what the ECU is Fault coding. The fault codes are just indicator. Note after reset of fault codes the Glow plug fault is not present.
Ok let's go back Andies graphs. After understanding how Absolute Pressure is defined as I now am longer confused. The M A P therefore has a max output of 5 volts and minimal output of 0 volts. Is it right that the sensor would give out 2.5 Volts when the Manifold is at atmospheric. There must be a voltage value above atmospheric when the pressure in the manifold is considered to be at Overboost. How altitude is taken care of is another mistery. It is likely that the output would never drop to 0 volts. Finally Andy concludes that other MAPs work differently. This is what make all these issues so hard to understand but Andy's bench test definitely will give functionality of the device but you need to cross check to see if it is in Specification. 😀😀😀
Thanks for ur explain , the map sensor division from the line on diagram is that ok or it's fails
+Hazem Alsaady If the readings fall anywhere outside the lines throughout the operating range then it's a fail.
Cheers Andy
I installed a new Dorman map sensor on a Honda Element , while doing other repairs and it put me on a wild goose chase , because the car would not turn on, the car would only turn on when i unplugged the Dorman map sensor.... it took me 7 days of trouble shooting ... when it comes to sensor go OEM or your car will not run right
Great video. You helped me diagnose my Toyota MAP sensor. However, I think you made an accidental statement at 9:34. "As the vacuum increases, the output voltage decreases". Per your test and charts, as the vacuum increases the voltage increases. Might have been a accidental mix up of terms; vacuum and pressure.
+LuvMy55Chevy I think you are right with that one. I meant to say resistance. I'll re-take it one day! Thanks for the feedback and I'm pleased it helped you fix your car. Cheers Andy
Hey Andy if we're really just varying the resistance with vacuum. pressure couldn't we just take a resistance reading from the signal wire while adding vacuum. No it will not correlate to a map but the varying resistance would indicate a working operation.
Totally can, just check supply voltage is at 5v+ & a good ground is also present.
Cheers Andy
if its faulty what effect does it have to the vehicle , i mean the map sensor.
Pls. send me a site where i can download schematic diagram of my old honda esi model 1994 so i can fix some issue i experience especially sensors. I'm afraid i can fry the PCM if i'll do some testing. THANKS.
A random question, but and seeing that you are in NZ how are things there since the last quake. Was thinking about doing a work cisa with a view to resident if things work out. I'm a mechanic so wondered if we are in as much need as house builders, yet guess as vehicles are needed to transport goods, we might be sought after too.
+James Barratt Hi, Sorry for the delay in getting back to you. NZ is fine, that quake hasn't made much of an impact here in Auckland.
Just be aware NZ wages for Mechanics isn't as much as many other countries and the cost of living is a much higher percentage of your income.
It's a nice place to live but quite different to all the marketing the country does to promote itself an an eco-friendly paradise!
Yep well im looking to the distant future really. I was under the impression with doing a few years in NZ, I'd get a resident visa, and be allowed to live in Aus then.
James do some research with the department of immigration. I,m an Aussie and I know that the relationship between our two countries exists for citizens. I could go and visit Andy tomorrow, buy a ticket, no visa. I would suggest that if you want to come here apply here. You can get work visa here for a year and then if you find a sponsor your in. Sean
Hi, I was given a 4 pin Ford 0 261 230 027 sensor. I don't have the car so I cannot test it in the car. I want to use it for an automation project for the school. How should I test it? I cannot find the connection diagram. Many thanks. Regards
did i hear you say that as the vacuum increases the voltage drops? I saw it the other way or am I mistaken?
That's correct. On some map sensors the voltage is around 3.7v at atmospheric pressure (WOT) & drops down as vacuum increases.
Hope this helps
Cheers Andy
am failing to find the position of the map sensor for my mazda demio DW 2 series ,its producing a dark smoke but its not burning oil. its chewing too much petrol
+caleb kakaka Hi Caleb, from memory I think the Demio has a MAF (Mass air flow meter) rather than a MAP sensor. It will be in the intake between the air filter and throttle body. Take it off and give it a clean with special cleaner - your local parts supplier should have this.
Hello Andy, I'm doing this test on my car, I back probed the signal wire that connects to ECU, and I'm loosing about 1v, the plug disconnected measures correct (close to 5v disconnected) - once connected I'm loosing 1v. what does that mean ? the rest is o.k .. the volts decrease when I increase vacuum.
So when connected you only have 4v supplied to MAP sensor? If this is the same for all sensors then you may have a bad earth issue? ECU should be putting out 5v supply on that pin.
@@AndyMechanic when the sensor is disconnected I have 4.6v - when it's connected I have 3.6 v. How would I go about repairing an earth issue?
I think you are plugged into the sensor wire & not the 5v ref
So the rav 4 does not follow the standard left to right Power/red....ground/Black....... Signal/yellow?
I have lexus 2009 .my map sensor have three wires. First wire is going 4.99v second wire is going 4.90v third wire is going 0v.can you please tell me which wire is which?
4.99v is the ECU supplied 5v reference. 0v is the ECU supplied ground & 4.9v is the signal wire - that's my thoughts.
Cheers Andy
I have a 4after engine whenever I start my car the rpm goes up to 8000rpm I have to switch the car off. I need some help
This problem got nothing to do with MAP Sensor, its about TPS, or Throttle Positioner Sensor.
Can you not do a resistance test on it
Nice video, but for the record, there is no Earth ground on a car. Cars have DC ground. Earth ground is the 3rd prong on an electrical plug. Cars are isolated from earth ground, what is called a "floating ground"
Good teacher .thanks im from srilanka
on vag cars the easiest way to check a map sensor is by taking it off the inlet and using an mittyvac and laptop with vcds
this way you van look at the outut in mbar within vcds and compare it to what your vacuum guage says
What are the types of MAP sensor?
how to find the map sensor on a 2004 Isuzu Rodeo direct injection
+Christy scruggs good morning Chris, I must be honest here, I haven't worked on one of those for a long time. However, Map sensors require a vacuum supply from the intake manifold. So follow each vacuum hose and the one that goes to a small electrical component usually with 3 wires to it should be your map sensor.
You could also go onto Google images and search for pics of the map sensor on your vehicle, that usually gives you clues as to its location.
Ultimately it's best to just download a PDF workshop manual, that will not only give you the location but also the test data you need too.
Hope this helps.
Cheers Andy
My map sensor only gives 3.55v regardless of the pressure I add or take away. It must be dead.
Yep. I'd say so :-)
thanks man
CARS LOVER
You know how I do it buy a brand new one if it's not it take i take it back 😂😉
My first diagnose was just like that I tested and it was a simple system with an alternator as a dead end. So we went to NAPA got a new one something happen so I took it back and told em while I was getting the part the car got towed so I'll come back when I get the car back.
Told my friend hey I dont know. So we pushed it to the shop down the street
Later we get a call back that it is don6
We go pick it up and for my curiosity o asked .. so what was the problem
The tech said . . . The distributor... hahaha
The guy at the store put the bad one back in the box and back on the shelf
Ready for the next sucker
Moral of the story is that now i can and will question all
.. my approach my equipment and my parts
Can I test it while on my car
+Heather Laski Hi Heather, yes, no problem at all. There will be 3 wires. One is an earth, one 5v and the other is the output signal that goes to the ECU. You'll ideally need a hand vacuum pump like the one I use in the video and a multimeter set on 20 volts DC will work.
Hope that helps. Cheers Andy
Jack black is a mechanic now ?
Funny! Lol
Why do most YT posters have to introduce and end their videos with amplified music?
+rayford21 It's done as an intro. Just like a TV series. These videos were made primeraly for students and they take a few seconds to settle down and focus. The intro was designed by Google. Thanks Andy
Fuel pump gedget
People actually live in New Zealand ?
I love your videos but the music make my teeth hurt 😵😵
Oh! Google made the music! Lol
necesito video de map para corvette 1984 croos fire
+jose colon
No, lo siento, no hay video para ese coche, no los tenemos en Nueva Zelanda
map on car????
ha ha i recentily bay two map sensors for 50$ in iraq
How about shortening your video intro..50 seconds is loooong
Thanks. Yep, done that, videos uploaded in the last 12 months or so do have a much shorter intro.
Thanks for the feedback
Cheers Andy
I would have to disagree! My kids were rocking out and it made a bad morning being stranded into a good one. People can just fast forward through the intro because they already do regardless of the length. Thank you for all you do