JBsZ06

I've been experiencing some weird drivability characteristics...and keep thinking I resolved the issue.

The tech II shows no issue...and sometimes the car runs good and sometimes it runs like crap..

Had the car tuned by 4 times and the tuner says its not in the tune but rather something else..(not the vette drs by the way)

Anyways here's the story and maybe you can help...

The car holds the tune for about a week and then drivability starts to degrade...

so last night I disconnected the battery and said lets see if that does..

So I reattach the battery and start the car this morning in the garage...(outside is raining big time) Don't know if its part of the issue.

The engine starts and revs up and settles at 2,000 rpms...then 3000 rpms...

I drive the car out of the garage and the cars driving good...but when I depress the clutch the engine continues to rev to 2,000 or 3,000 rpms..

Once the engine warms up to normal operating temperature the pcm kicks into closed loop and the idle returns to normal 900 rpms..

So my question is:

Assuming the computer has been in the past adjusting for some "ISSUE" what is that issue? Remember I disconnected the battery overnight to clean up old history and start fresh...

Where would you look?

1)Would the issue be a throttle positioning sensor?

2)or the motor on the throttle body? How about a leak of air around throttle body?

3) intake manifold leak?

4) bad maf?

5) coolant temperature sensor is bad?

6) Injectors have gone bad?

7) bad fuel regulator/fuel filter?

8) Map sensor?(how to fix?)

9) head gasket leak? (coolant looks fine)

Tech II shows nothing wrong.

The tune works great as long as I reset it everyweek. During the week long of a tune something mechanical is causing the car to go "off tune"

This mornings experience leads me believe its a sensor or a air leak or fuel leak ?

What do you guys think?

What makes the idle go up to 2,000 or 3000 rpm steady at cold start up with no gas pedal action and stay there until the car warms up and goes closed loop (with computer readusting to bring the idle down) .... on a car removing the pcm tune from the equation?[/

JBsZ06

One more thing..once the car is warm and the car is started up the idle settles at 1500, then down to 1100 and then to the normal 900rpms..

Any ideas would be appreciated.

Like I said the tuner said its a mechanical/or some other issue and not the tune...

I beleive him yet I need to have an idea of what parts to replace..

Any insight would be appreciated..

JB

JF-WS6

iTrader: (1)

I don't know crap about tuning, but the guy that takes care of my car did a maf-less tune which eliminates your maf all together, he recommended this because he said if I would keep my maf I could run into some problems with my tune down the road. Its now been a year and a-half and I've had no problems.