Idle fluctuating when engine warms up

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Ulliboyyy

New member
Joined
Sep 30, 2020
Messages
2
Got myself a 1998 1.7l 16V Puma last year. It was driving nicely until a couple weeks back. Had the MAF sensor replaced because the engine was revving slow, and it fixed the revving problem. Had the ECU reset also in the process.

Since then the engine has been idling rough, fluctuating usually from 600-1100 rpm, sometimes almost cutting out. Only happens when the engine is warm, though. On a cold start it idles normal until it warms up. Also no problem when driving.

Going to check the idle control valve and run OBD on it. Any other ideas?
 
Fluctuating idle is a tricky one to pinpoint sometimes but starting with the ICV and checking pipes for splits is a good place to start.
 
Have you still the original 'slow revving' MAF? Clean it with brake cleaner, the wire inside is brown-blackish, should be shiney. Be careful not to break the wire. Don't touch it with anything, just gentle squirts of brake cleaner and let it dry. Refit it to the car, and I bet it will rev and idle nicely... :wink:
 
Problem solved! Checked and cleaned the ICV and checked vacuum lines with no success. ODB came out with a "P0171 System too lean (BANK 1)". With help from a local Ford technician we found out the inlet manifold gasket had a leak, fitted a new one and now shes running great again!
 

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