MAF location please?

Will the MAF sensor keep my car from starting?

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

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?

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.

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.

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?

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

Where is the mass air flow located on the car?

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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