I need to know why the hell my car will not hold it's rpm. Every time I go to the track I try to stablelize my rpm at the stageing light's and my rpm's just fluctuate it just goes up and down. Now thier is no check engine light on and no codes to be reset, I thought it was the idle air control valve so I replaced and i'm still in the same situation. Any help is appreciated thanx.

 

Seriously, try resetting your ECU anyways and letting it idle for around 5 minutes. You may want to check out your O2 sensors too.

EDIT: And radiator fluid level.

 

Check your throttle cable maybe?

 

I already reset the ecu and all fluid levels are fine, Oh and the O2 sensor was replaced about a month ago. Throttle cable is also fine.

 

check all vacuum lines. Does it do when it is hot or cold? does it do it at certain times? what was the last thing that you did to it? Check all the simple things like ignition wires, dirty TB.

 

How fast does it fluctuate? And what kind of range are we talking about here? If it's a small range, like a hundred rpm or so, then it doesn't really matter and I would say it would be an O2-sensor related problem. Mine actually does that a bit also, and it was more pronounced with the old O2. I know you've replaced yours already however, so hmmmmm...

 

I noticed you're in the phoenix area, what part? Does it happen at idle too? What ECU program are you running? Is it a recent problem or has it been happening since you swapped the engine (or bought the car)?

 

mine does the same thing...when im in the lower RPM's it jumps all around like the actual needle moves realy fast too....no codes no check engine...i dunno what it can be...any help for us???

 

If it does it all the time, i would suggest that you're missing a ground somewhere and recheck your wiring... If it's only when revving up or moving but not at idle I would suggest that you are shorting or grounding out somewhere, loose wiring... It sounds like a wiring issue... I've helped several people fix this problem before... It was a different issue with each one, but all related to wiring... Just check your harness and grounds...

 

Have you bled your coolant properly?
And is your timing set correctly?

 

throttle coolant screw on the underside of the t-body?

 

Well fellas it does it when I try to stay at a set rpm (4000rpm). And yes it will do it sometimes when i'm just sitting there idleing at a light. One thing I will do is bleed the coolant system and check for any loose wires or bad connections. Any other things you guys might want to suggest will greatly be appreciated thanx again.