Grand Am Drives poorly from stop after it is warmed up.

[DGHIBNER63]

I have a 1999 Grand Am with the L4 Motor. It is an automatic. The car starts and runs fine in the morning. If it is shut off after it is warmed up It restarts o.k., but runs sluggishly from a standstill until it gets going, or is allowed to idle for a minute or so. The motor has been rebuilt in the past year, but has always had this issue. Recently the Maf has been checked along with a full tune up, including fuel filter, wires and plugs. I am wondering if this is a fuel injector problem, or could it be related to the coil pack, or are there other easy-fix or check items that could be causing this problem? What about the cats? Any help is appreciated. I am pretty mechanically inclined and am not afraid to get my hands dirty on this so please fire away.

[3100]

If this happens every time you accelerate I would check MAF and TPS sensors with scan tool live data. MAF should show 3-4 g/sec at idle and TPS should be about .54-.65V at idle and both should gradually increase with throttle plate opening. Also try to disconnect your O2 sensor and see if problem disappear.


how was your MAF checked?