Johns98TA

iTrader: (2)

Hey guys, I'm hoping somebody can help me fix my stock tune (or fix the problem). I have a bone stock 1998 Trans Am WS6 (M6). I bought the car with about 30K miles on it, and now have about 40K. The only mod on the whole car is a dynomax muffler and aftermarket tips.
Before you flame me for tuning a stock car, hear me out.
I bought HP Tuners because I want to learn how to tune, and this website has been a great resource to me.

OK here's the problem. My car has always done this, as long as I can remember. When I am decelerating in 2nd gear and I push in the clutch to come to a stop, the idle will dip down very low, stumble, and then pick back up to normal 1000rpms or so and stay there. It doesn't do it when the engine is cold, only when warmed up. It will do it with the AC on or off. It never has any other problems idling or starting. It doesn't do it when sitting still and revving the motor. What is causing this, and how do I fix it? I just posted in here cause I figure maybe I can tune it out...

moehorsepower

iTrader: (3)

If its bone stock then you should not have to get into the PCM to fix this, there must be a mechanical problem like a vacum leak.. There is nothing wrong with tuning a stock motor, my customers will gain up to 3/10 ths in the 1320 with a street tune on a stock motor...

Johns98TA

iTrader: (2)

Well I did supsect something mechanical, but then why would there be no symptoms under any other conditions? I mean if it had a vaccuum leak, wouldn't it act screwy when sitting still also? It only does it when I'm driving down the street and I push in the clutch and let off the gas to push the brakes. Once I'm stopped, I can rev the motor, blip the throttle, etc.. and it will not repeat the problem. So I drive off to the next stop sign, and it will do it again in exactly the same fashion. Would a bad IAC valve cause this? Maybe it's sticking or something? You guys know any way to troubleshoot this besides throwing parts at it? I'm a skilled bike mechanic, but I'm still learning the wonders of cars...

wait4me

iTrader: (10)

Vac leak would cause an idle that is too high.

I would say the throttle blade on your application is not open enough. So the throttle cracker settings are just wrong right now. If you turn the blade up a little your problem will be gone.

Johns98TA

iTrader: (2)

Thanks for the reply. I had read a write-up about the throttle blade adjustment somewhere on here, but I thought that was only for guys with cams and other mods where they couldn't get the car to idle right. I'll go back and re-read it.

I will definately give it a shot though since I have all the tools to do it correctly. I'll let you guys know what I find out.

You have any recommendation for adjusting the throttle-cracker settings in my tune?

PS: I love this board!