MAF location please?

Here is the location of the MAF and the IAT which is the same part. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

will the MAF sensor keep my car from starting?

Yes. Only Chrysler has never used a mass air flow sensor. On all others, that sensor has the biggest say in fuel metering calculations. All air going into the engine must pass through the mass air flow sensor. It is important there are no loose hose clamps or other leaks in the fresh air tube between that sensor and the throttle body.

There are a number of other things that are much more common causes of crank/no-start problems.

i changed it and the fuel reg.fuel pump and filter all new from front to back egr valve thanks

Have you checked all the vitals, fuel pressure, ignition, any codes set? scan as not all codes will set a MIL.

My car randomly has engine surges/stumbles that, once they begin, will get worse and eventually become so severe that it will stall. I have to try and try to get it restarted and then limp home. Sometimes the car is better the next day, sometimes in two or three days. Then I can drive it again, but sooner or later the trouble starts again, usually within about 50-60 miles of mostly highway driving. There is no check engine light and no trouble codes even when it cuts off. I have changed the fuel and air filters. It passed all the fuel sys and vacuum tests I did on it, even when having the problem so bad I would sometimes have to restart it to continue the tests. I suspect a bad MAF sensor, but can't prove it. When running, none of its numbers seem noticibly off on my scan tool. However, I get readings from it when the engine is off and the key on--when I assume it should read 0.0 like my Mazda and Toyota. It usually scans betwen .2 and .5 lb per min with teh engine off, but has given readings of 6.4, 11.7, and even 20.4 (not accurate even if I was running 100 mph). The reading stays steady as long as I have the key on, but turn the key off and then on again and the reading changes to another random number. Crank the car, and it goes to normal idle numbers like .4 to .6 lb. This continued even after I cleaned the sensor wires. Are the false engine-off readings a sign of a bad sensor or is there another problem with the car?

From your description I would have to lean towards a bad mass air. When the engine seems to be running normally, had you tried giving the MAS a rap with a screwdriver?

Yes, I tried the screwdriver thing. It did not seem to affect the way the engine ran or the scantool readings with the engine on or off. That was one of the reasons I still wasn't sure if the sensor was bad or not. Unplugging the MAF also did not affect the running as far as I could tell, but I did not drive it like that, just revved it in park.

My wife drives an '04 Impala and just for the heck of it I tested her MAF and at a warm idle it read .55 and with key off it was 0.0. and her car runs great.
Everything you describe points to MAF and if I were in your shoes, I'd change it. Keep in mind, we can't rule out the ECM here either, but that's usually the last thing I blame. Let me know.

Thanks so much for the info. Since your wife's reads 0.0 with the key off, I've got a replacement MAF on the way. Will let you know how it goes in a few days when I get it on and test drive it.

OK, let me know how it goes. I can always use the info to pass onto others.

Sorry, it took so long to get back to you on this, but its been an interesting time with the car. I got the MAF changed no problem and it ran fine for about 200 miles, then had the problem again and died on the way to work. Couldn't get it home this time and so I had it towed to a shop. Figured they could diagnose it while it had the problem. They said ECU bad so replaced it. Once they replaced it, found that crank sensor wire had gotten against the rear exhaust manifold and melted and shorted. Said that killed the ECU. Not sure about that last part. I can believe the bad crank sensor caused the performance problem and may have sent a reading to the ECU that told it to go into limp home mode, but kill it? Shouldn't it be tougher than that or blow a fuse or something first? Maybe they just told me that cause they already had the new ECU in the car. Anyway, picked it up yest, drove it 90 miles today and it ran fine for 50. However, while doing some in-town driving, the check engine light came on. Set two of the same code for catalyst not performing at peak efficiency. Think it set them when the catalyst monitor ran first time after reset, but not sure. I reset it with a scan tool and it hasn't come back in 40 miles of driving since. I can't tell if this is related to the prior problem. I am a little afraid it ran so poorly (very rich at times) or shook so violently (it was REALLY shaking hard when it malfunctioned) when the ECU went that it damaged the catalyst. Or it could have nothing to do with any of that or just be an O2 sensor. Got to love 200K cars . . . . So, that is the update. If you have any thoughts, let me know. Otherwise, I hope this helps someone else.

We had problems with my car stalling, we disccnected the mass air flow sensor, my car is now in safe mode, what does that reallt mean? N is it ok to drive around like this?

Is the reduced performance light on?Have you had it scanned for codes yet?

No on both questions u provided. It seems to act normal once again, but we will be replacing the mass air flow sensor, to see if that is the problem with my car's surging, stalling n rough running

The codes in the computer before you unhooked the mass air flow sensor would have really helped.

Where is the mass air flow located on the car?

the mass air flow sensor is located on the air intake hose going to the throttle body. right near the air filter housing...........................

Our Impala has really gotten bad gas mileage and does not accerate good now. It has the engine light on. We took it to a dealership and they said it coded EGR valve, massive air flow sensor, catalytic converter and oxygen sensor. We have replaced egr valve and massive air flow sensor, exhaust manifold gasket and transmission filter and fluid. It has done nothing. It still hestiates when accelerating and then surges and also doesn't go up our hill over 30 mph. My husband is a disabled veteran so we are having a hard time trying to find out what is definitely wrong with it. Please give me an ida.

Hi...looks like we have the same problem....Searching this Web site I found info ...hope it will help you see below

Rough acceleration until about 35-40mph

Posted at Tue Jul 11, 2006 5:10 pm
By raks1980, New to the forum
(10) Give Feedback | Votes: 0


Hi, can you please advice.
I own 2002 Chevy Impala 3.4L engine, 111,000.00 miles.
My car doesn't accelerate well until about 40 mph, especially when it is going up the hill or from the start in general (it works fine downhill). I have to really press the gas pedal and then when it goes over the 40 mph it works ok.

Check engine light indicates EGR valve, so I put a brand new valve and it still does the same thing.

In the process I discover that when driving without EGR valve connected to the computer my car works fine but it won’t go faster than about 65-70mph. After 70 mph when I press the gas pedal it actually decelerates and engine starts heating.

At idle engine works fine but when trying to accelerate you can hear really fast RPMs but it just doesn't deliver power to the wheels ?

It also produces roaring noise even if I press the gas pedal to the max., doesn't react to the until it passes 30-40 mph.

Please help, Max A.


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Posted at Mon Jul 17, 2006 11:37 am
By raks1980, New to the forum
(10) Give Feedback | Votes: 0


1.The problem was my clogged catalytic converter ($275 in mieneken).

Due to the fact that it was clogged the upper block/portion of the engine and somehow spark plugs had heavy carbon deposit.

2.Emission Flush ($180)
3.Spark pugs and wires ($170)


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Hi again....info below I found in one of the Web sites


Why do converters go bad?
There are two ways a converter can fail, it can become clogged or it can be poisoned.
When catalytic converters fail they normally clog up with debris and block the flow of exhaust gas from getting out of the system. This will cause tremendous performance problems. In extreme cases it will prevent the vehicle from starting at all. Most of the time it just limits engine performance by choking the flow through the engine. So how do you check a catalytic converter without removing it from the car?? Sometimes an indication that a converter is clogged is that you don't go any faster when you push the gas pedal down. In addition there usually is a noticeable drop in fuel economy associated with a clogged catalytic converter. A totally clogged converter will cause the engine to die because of the increased backpressure.

Hi guys, so Ive got a MAF/VAF code. saying low voltage on the A circuit of the mass air flow. Although I did find the wires going to the coolant sensor melted to the exhaust, so I'm fixing that today. Looked like the ground wire was cooked. But is there an easy test I can do with my multimeter besides checking for the 5volt ref. wire going into it? its only a 3 wire MAF. Maybe just checking the signal wire going out while the running? thanks all

ok,,,so my 5v ref. isn't there. only getting about 2.5V. also 2.5v at air intake temp sensor. But 5v at MAP sensor. so I'm assuming theres a splice somewhere that's bad. anyone have a wiring diagram for this circuit?

I answered this previously but you may have fried the computer when the other wiring grounded to the manifold.

Hello Does anyone have a wiring diagram for the 5 volt ref for a MAF and where it goes? only 2,5v at MAF. I need to trace it back to splice.

pink is hot and goes to fuse box engine devices. Yellow wire to computer and not spliced pic shows connection at computer.

Pink has battery power to it, just getting 2.5V ref on yellow wire. also only getting 2.5v at air temp sensor on the boot from air filter.

it can either be a poor connection or wiring burnt as I answered your other reply where you said harness burned. so you may have fried computer check at computer what you are getting I sent that in second pic. it's marked.

Does air intake sensor run 5V to ECM by itself also?

see pic for info. but with what has happened I think you should have a mechanic look at this for a cheaper faster fix....and yes it should have 5 volts as well.

ill check out the output voltage at the ECM and its ground and go from there, I just figured all the 5V ref were on the same circuit, but after looking at the wiring diagrams I can see they come out of all different pins. ive diagnosed things like this before. I just didn't have the diagrams to check it out. plus someone has hacked the electrical system in this car. theres cut wires under the seats and dash. my guess is someone had a sound system in it a one point. thanks for the help though.

the speed density or air intake is at #50 on pcm.

2000 Chevy Impala 6 cyl Automatic 100649 miles

I got my grandfather's '00 Impala scanned today and the resulting test code was PO 102 Mass Air Flow Sensor Circuit Low. Do I need to replace the Mass Air Flow Sensor completely or is it possible that there may simply be a wiring problem messing with the sensor. Any suggestions would be appreciated.

what engine does it have,3.4 or 3.8?some things to check before you replace any part,Objects blocking the MAF sensor inlet screen.

• Vacuum leaks around the intake manifold.

• Vacuum leaks at throttle body.

• Vacuum leaks at the EGR valve flange and pipes.

• Crankcase ventilation valve malfunctioning, missing, or incorrectly installed. check these and post back with engine size and will advise from there.