belsy

2005 6 speed with headers and an open air box otherwise stock. Recently my idle does not decrease as quickly as it should rev it up to quick rev to 2000 or so and slowly drops back down to 8 or 900 rather than dropping quickly otherwise running fine but this can be annoying in traffic! Any thoughts on what this could be it just came out of nowhere no changes no codes, any thoughts or suggestions would be appreciated

jamieo

I would probably start by cleaning the MAF sensor and throttle body.Will cost less than $10 and only a few minutes of your time.It can't hurt to try.

dave4881

Get it on Amazon...

C5 Diag

I’d check your throttle body for deposits on the bore where the throttle plate closes…also check that the plate moves smoothly as someone pushes on and then releases the go pedal with ignition in run.

DrKrieger

I have the exact same problem.......cleaned the MAF sensor, and TB, even replaced the MAF sensor AND the TB.....still does the same thing. SC'd LS7, ported and polished heads, Belanger Custom Tri-Y Headers........I just "put up with it" however it is annoying. I took it to the dyno AGAIN and the tuner has no idea why it's happening.
Any suggestions would be appreciated.....

PMPerformance

Typically in other cars I have experienced this, it is IACV problems, specifically the decay rate.
Not sure if these cars even have an iacv, but if so, I’d check that out and clean it out. They can get gummed up over the years.

C5 Diag

No Idle Air Control Valve.

wjnjr

If the problem has been there since you built the car, ask if he checked the idle related tables like base airflow, coast down spark, adaptive idle, etc. They can all effect a throttle hang if they are off. It actually takes more time and effort to get driveability right than WOT when tuning a custom build like yours. That's where the tuner's skill and experience come in.

If he gives you a blank look, find another "tooner" .

According to the OP, his problem occurred suddenly. The idle hang in this case will most likely be caused by a mechanical problem like a sticking throttle butterfly or a vacuum leak, because tunes don't just spontaneously change.

Good luck to both you guys, let us know what the fix is when you find it.

jeffs64

Tuner