Hi all, new on here, try and keep this short, my 3.4l 996 started idling fast, no fault light, computer said high idle rpm, reset now car wont idle! from start up it idles very irratically (low) with what seems to be a backfire or misfire and stalls, took engine out last week, checked ims and rms, changed aos kit, refitted engine and fitted new plugs, coil packs fuel filter and o2 sensors but still the same? has anyone any ideas where to look next? any advise much appreciated
regards
Burto

 

Might be the maf/throttle body just needs a good cleaning...?

 

sounds like a vacuum leak to me.
With the engine running, try to remove the oil filler tube cap.
If it is really hard to remove because of strong suction then it usually points to a vacuum leak and most often from the AOS. If you have changed your AOS, then perhaps you missed some hose hookup or gasket misalignment?
Pete

 

I'm going with MAF sensor. Might need to be replaced. Cleaning didn't work for me

 

Hi Burto,
Did you ever find an answer to this? My 2003 C4S is doing the exact same thing. I've cleaned the MAF and throttle body and run Seafoam through it and still no change. I'm at a loss and hoping for help.
Thanks
Charles