CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Grand Prix 2001 MAF Sensor Problem PLEASE HELP!

I have a 2001 Grand Prix GTP that has given me nothing but problems ever since I have had it! The current problem is with the MAF sensor. A couple of months ago I was driving down the highway and the car just died. I pulled over, put the car in park, restarted it and continued driving for another 1/4 mile before it died again. After restarting the second time everything was fine, I made it home, and didn’t have any problems for several days. Throughout all of this there were never any symptoms of a problem or any odd noises. After a month or two of sporadic dying my check engine light finally came on! It ran a code saying my MAF sensor was bad. I replaced it and immediatly had the same problem. I took the part back to AutoZone and they looked at it and said that the part was no good and exchanged it. I have gone through three parts from AutoZone to no avail so I finally took it to a small town shop. They said the same thing as AutoZone, bad part. They got an ACDelco MAF sensor and I have had the car for about 2 and 1/2 weeks now. Just yesterday it died twice on me! Please help! I don’t know what this can be. The longer that i run each MAF sensor the worse the dying episodes get - the car won’t start up so easily, the rpm’s start going crazy at idle or even going down the highway. It seems to die most often when i am idling at a stop light but it has happened several times when the car is actually moving. I can’t take it to a shop yet because it doesn’t happen often enough to diagnose a problem. Please help, I am sick of getting stranded and backing up traffic!!

First you should forget the MAF sensor - it seems likely that you have eliminated it as the problem. The OBDII code that comes up w/ the CEL never tells you that a part is bad and should be replaced. It gives you information to use in diagnosing a problem.

There are quite a few codes that can point to potential MAF problems. What was the actual code that came up? (e.g. P0100) Presumably to CEL is still on or at least on some of the time. Have it scanned again and report the results.

Also say something about the rest of the car - how is the air filter? Is it a paper filter or did you put in something like a K&N? When is the last time you changed the fuel filter? plugs & wires? etc.

I only got the CEL once and it was code PO102. Air filter - new (one month), paper and plugs and wires were replaced one year ago. Dont know about the fuel filter. I just went today and had the pigtail wires(?) replaced for the maf sensor. When I got home, I took the engine cover off to examine the work and tried fiddling with the maf sensor to see if the car would die and it choked a bit. I have been told that that would indicate a bad maf sensor. It also seems to be a bit shaky at idle-not nice and steady.
P.S. I dont know anything about cars so excuse my car lingo

P0102 - Mass or Volume Air Flow Circuit Low Input.

The ECM is getting a bad signal from the MAF sensor. This could be a bad MAF, or a problem with the circuit. I’m surprised if the signal line hasn’t been traced all the way back to the ECM to insure the circuit is in good shape. This is now 4 replacement MAF sensors. The odds of getting 4 bad ones in a row are astronomical.

I’m also wondering if there is something physical that is damaging the MAF sensor, especially right at the connector. Are there any loose or moving parts directly in the vicinity, or anything that could be tugging on the wire harness? Are the motor mounts good, or can the engine shift or rock excessively while driving?

Don’t believe anything is rubbing or damaging it. In reference to having the pigtail wires to the maf sensor replaced - If the wires were bad before, would it have ruined the maf sensor? Sorry if thats a stupid question but i really dont know a whole lot about cars! And by me pressing on the maf sensor and getting the whole choking response, doesnt that mean the maf would be no good?

Or the connection is weak and no good. Or the wiring is damaged further in the wire harness. I’m sure your mechanic will want to double check the circuit, too before replacing the MAF sensor for a 5th time.

Code or no, I don’t think the problem is MAF related at all.
There is no way on Earth you’re getting mulitiple bad MAF sensors.

As to what the problem is, that’s pretty much a wild guess without car in hand.
Fluctuating idle speeds and dying at low speed, possibly a faulty Idle Air Control valve or IAC control problem.
Dying at highway speeds, possibly a failing fuel pump or failing fuel pump control circuit.

How many miles on the car and is it known if the fuel pump, or even the lowly fuel filter, was ever changed?

I would just want to be fairly sure that the problem isn’t with the ignition switch. If the voltage that reaches the MAF (Mass Air Flow) sensor is low, the signal voltage the MAF sensor sends on to the engine computer (ECM) will be low.
The ignition switch sends battery voltage (12+ volts) to the MAF when the ignition switch is ON. You can measure this voltage, with the electric plug disconnected from the MAF, on the terminal of the PINK wire. http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152800a3456 The voltage should be within a volt of the battery voltage.
Turn the ignition switch off and ON numerous times to see if there is the same voltage each time. If the voltage is low (lower than battery voltage), or not present at any of the times the ignition switch is switched off, and then ON, there is a problem with the ignition switch.
That repair shop you used, I wonder if their problem is greed (profit on an MAF), or ignorance. At least, ignorance is curable with learning. Greed isn’t.