Idle speed

[gt fan nik]

Hi i have an 86 350i it was idilling great at 850 now it decides to idle betwwen 1000 and 1100. Can anybody help me sort it out.
Will it need tuning etc.
Cheers Nik

[chunder]

Nik,

If you do a search on this forum on idle there will probably be quite a few previous threads that covered the topic fairly comprehensively.

I assume it is an early flapper type injection system and there could be many causes such as - air intake hose leak, overun valve letting by, extra air valve stuck slightly open, throttle butterfly not set correctly (throttle stop screw moved and/or throttle position sensor not set correctly), faulty water temp sensor, could just be idle adjustment screw setting.

If not any of these then could also be AFM or ECU but check the easier things first.