Fluctuating RPM's!!

These Grand Prix have been nothing but problems for me this is my second one. My first one the engine died. Now this one 1999 GTP is having trouble. The rpms seem to jump like 200-400 rpms at some points. Only happens when I'm driving not idling. On the highway and streets, any help?

Thinking it might be the cat, maf,??? What else. I'm going to scan it tomorrow so it might pull something but there is no lights on at all.

Most likely it's the car asking for a tune up. Try ensuring it has fresh plugs, wires and clean the throttle body.

If that doesn't work, then have someone check that your maf and TPS are good, as they can cause the TCC to lock/unlock as well.

If that's not the answer..it's TCC oscillation and you have trans issues.

Originally Posted by Bessesen2

These Grand Prix have been nothing but problems for me this is my second one. My first one the engine died. Now this one 1999 GTP is having trouble. The rpms seem to jump like 200-400 rpms at some points. Only happens when I'm driving not idling. On the highway and streets, any help?

Thinking it might be the cat, maf,??? What else. I'm going to scan it tomorrow so it might pull something but there is no lights on at all.

Could be bad o2 sensor.

I know i could make the Regal fluctuate RPM on cold idle by setting o2 switch points too low in tinytuner.