MOVENU

I have been having idle problems with the car for a few months now. The rpms' jump up and down and the car occasionally stalls out upon start up (the car never stalls while driving). The stalling when I try to start it only seems to happen when the engine is warm, not when I first start up the car for the day. The engine also seems to run a little hot which I don't know if it's related but thought I'd mention.
There are no codes / cels on. The car does have a K&N cone air intake which came with the car. The car drives fine, acceleration seems good, and gas mileage seems normal.
So far I have replaced the spark plugs, coolant level sensor, carbon canister (CEL was on for it previously), evap purge valve, MAF, and had it checked for vacuum leaks.
Any other possibilites you guys think might be the cause? O2 sensors, fuel filter, something emissions related?
Thanks

jordanturbo

When I start my 02 C4s cold its high idle is about 1100rpm. it will dip once or twice down to 700rpm before jumping to 1200rpm and settling out at 1100rpm again. I took a video of it posted it in a few forums, but have got nothing conclusive. It seems to be common with no solution found for the most part. I have a Porsche Scan tool, I have no codes, soft, hard, current or stored. I have a new MAF, o2 sensors, spark plugs, coil packs, air filter, serp belt, coolant flush, recently pulled my tranny, inspected and replaced my IMS bearing and rear main seal. AKA I have done pretty well all possible general maint. I bought my car at 40,000km and it is currently at 104,000km and it has done it since I have taken possession of the car. I find it runs a little better with fresh oil, also I changed the oil I use and it seems a little better as well. I was a mobil 1 feind but switched to Liquimoly Toptech 5400 5w40 oil which meets porsche specifications.

Shark Attack

Miles, year?
I ran into this when my AOS little rubber tube failed.

D6lc

my 04 used to run rough jumping revs up and down, I cleaned the throttle body but it didnt help. it was under warranty so the dealer looked into it, struggled to diagnose the issue and in the end replaced the throttle body. Idles perfectly smooth at just below 800 rpm now

MOVENU

ok. I was thinking of getting the throttle body cleaned. That was my next course of action. The car is a 2001 with 71,000 miles on it. I wasn't sure if the k&N might be causing any issues with airflow or metering but these seem to be a pretty common mod for most people and the actual filter is brand new.