sporadic accel. problem

[edible_eye]

Good morning, all. I browsed several pages of questions and unfortunately couldn't find a question close enough to mine, so I figured I'd give this a shot. My car is a '99 Grand Am SE. The problem I'm experiencing (abrupt loss of acceleration power, as though the engine simply stops working although it never feels as though it will stall) is sporadic - sometimes it happens, sometimes it doesn't - and it doesn't matter whether the car is warmed up or still cold. It doesn't matter whether I'm traveling on the highway or a side street. It has only to do with acceleration, usually when the tach jumps over 2000 rpm's and when it does occur, (power cuts out) I can't accelerate - or better said, acceleration just dies. If I lay off the accelrator, I can once again get power to the engine. Actually, as long as I keep the rpm's at 2000 or below, it's fine and I don't experience the loss of power.

Also, there are times when I can feel the transmission "kicking in" when the power surges back. Sometimes, the Traction Control light comes on, sometimes it doesn't. Before I had the spark coils changed, the ABS light sometimes came on but that hasn't happened since they were changed.

I've had the O2 sensor replaced, passenger side I believe. I've had a tune up done, the spark coils replaced, one of my mechanics lifted it and banged the cat which revealed nothing. I haven't heard any noise coming from below anyway. Two mechanics have taken it on the road and unfortunately were not able to reproduce the symptoms. I know very little about the mechnics of cars, especially what's produced these days so my brain is worthless in trying to figure this out. There have been no engine codes to decipher. My mechanics are stumped and I fear I might have to go the route of the dealer.

Does this sound like something someone here has heard about before and if so, what would you recommend?

[knuke]

I had a similar problem on a different make, it turned out to be the throttle positioning sensor.

[edible_eye]

thanx, knuke. i'll ask them to check that out.

anyone else with experience?

[BNaylor]

Originally Posted by edible_eye

thanx, knuke. i'll ask them to check that out.

anyone else with experience?

One item you should check is the MAF (mass airflow sensor). Typically, if you have one that is defective or dirty, it will affect your car when accelerating because the ECM/PCM computer operates in open loop mode
due to engine load, etc and relies upon the sensor input. The MAF sensor signal helps controls the fuel injection. A lot of times you will not get a SES light or DTC error codes.

To illiminate it as the problem or troubleshooting, just disconnect the quick disconnect electrical connector on the MAF. The MAF sensor assembly should be a black ring (oval) before the throttle body input and air intake. Take it out for a spin and see if the problem goes away.
Note: You may get a SES light during the test. Your initial idle may be a little erratic at first until the engine warms up.

If it fixes the problem, replace it and if not just reconnect and look elsewhere. But try the basics such as spark plugs, wires, and fuel filter first. You could try cleaning the MAF sensor flow wires but it is not recommended but worth a try. Be careful not to break or damage the wires and electronic component.

A MAF sensor problem is very common on GM cars 1997 and up with mileage.

2001 Buick Regal GS/1999 Regal LS/2002 Olds Alero GL2 and 1997 GrandPrix GTP

[edible_eye]

thanx, bnaylor. i appreciate you taking the time.