Rough Idle- but not a surge?

[e30details]

Hi everyone,

I’ve done a lot of research on the forums on this topic. The ICV, AFM, timing belt, water pump, thermostat, throttle body boot, and seals
have all been replaced. But the car still idles between .5 and 1k RPM. Any ideas?

[It's Soda Not Pop]

Vacuum leak.

[It's Soda Not Pop]

Also did you buy a OE bosch ICV? or Chinese knock off?

[82eye]

as above, however, i'd smoke it for a definitive leak test.

edit : fyi the hamburg tech icv is hamburger tech in operation and has caused the same issue.

[packratbimmer]

How about the throttle switch?

[DesertBMW]

you don't even say what car you got, not all M20 have the same engine management, then how can someone help you when all you say you replaced bunch of parts and you got low idle, it could be anything.

[e30davie]

Can be anything!

Do a compression test, maybe one of your valves are leaking........and if its not at least you'll know the condition of the engine.

[Northern]

smoke test that bitch

[e30details]

Thanks for the thoughts- I'll start with a smoke test...it's worse on cold start. It does a surge, then It almost dies and smells very rich in the garage. Once it warms up it's fine. the surging while cold is why I thought it was the ICV or AFM but with both of those replaced I'm stumped.