Can anybody help me solv a problem with my 91 gxe? I just rebuilt my engine: new bearings, crank, rigs, water pump gaskets, etc. and installed a wsp y-pipe. Now heres the problem. when I go to start the engine when its cold it runs a little rough, it jusms from about 2000 rpm's to about 1000 rpms and pendulates up and down. It does this for about 5 minutes or until the engine is warmed up. Now when the engine is nice and warm the car runs great. It runs very smooth. I only have 400 miles on my new rebuilt engine. My question is, is it normal for the engine to run fast when I start it cold, or should it be running at normal rpm's, say around 800? I have advanced timing at 20 degrees tdc and have checked it over and over again but I know thats not the problem cause it runs great when its warm. However it did stall out one time at a stop sighn when I gave it alot of gas, but when I slowley give it gas it runs fine. Also when I put the car in park ater driving it for a while the rpms jump back up to 2000.. Can somebody help?

 

Since it does it mostly when cold, I suspect injectors..fuel probs arr alway more pronounced when cold. Yes it shoudl idle near 1600 when cold. If it fluctuates alot, it might be a vac leak too. Thats the best I can do over the web. Keep posting

 

Since it does it mostly when cold, I suspect injectors..fuel probs arr alway more pronounced when cold. Yes it shoudl idle near 1600 when cold. If it fluctuates alot, it might be a vac leak too. Thats the best I can do over the web. Oh, check your TPS too. Keep posting

 

Its also the primary symptom of a bad O2 Sensor!

If its and SE and you search there's a O2 sensor test that you can run that displays the results through check engine light on the dash board. a simple procedure only requires a smail screw driver to put the ECU in diagnostic mode. If you can't find it let me know I'll look it up.

 

I did'nt want to have to mess with the ecu because I thought that I would have to reset it. Dosnt it store information and run better the longer it is being used? Can I just disconect the o2 sensor and do a cotinuity test on it? My car is a GXE too. I guess if it must be done then I should do it. The green light is the only one that comes on when I am running it and it flashes when it is held at 2000 rpms. As for the fuel injectors I did have a little trouble with one of them and I found that the wire was loose, so I sprayed it with electrical cleaner and made a tighter conection, after that it runs perfictly smooth when it is in drive. I already replaced 3 injectors and the others read to be fine. I dont know if im just being picky and the engine is just too cold to run smooth or if there is some other electrical problem I will look at the O2 sensor and do diagnostics.. But would that be the reason it stalls when I punch it at a stop light, because before I rebuilt the engine I could punch the pedal to the floor and it would not stall at all, just take off.

 

I just put the car into reverse after it was running for about 5 minutes and the engine droped way down to less than 500 rpms. It sounded like it was going to die, it was strange when it did, I saw the lights dim down on the dash and the headlights also. Now when I drive down the road sometimes the lights will all dim down and a power loss will follow.