please help,i've bought a fiesta turbo ofab with t3 ect,when i got it the idle was 1500rpm,now when revved it seems to stay up to what you rev it to and hold for around 3 secs before dropping down to 15-2000 rpm,iscv was changed today but is still the same as the old stripped and cleaned one,if i unplug the iscv and rev it the revs drop instantly rather than holding,the car drives and boosts fine and will idle by tensioning the cable fine.

where do i go from here?

Lee

 

I got same problem
Cleaned the ISCV today with carb cleaner, cleaned all connections and retightened all vacum hoses. Still no joy. Idling about 1500 / 2000.

However, possibly related...

1. Last week, the interior heater fan and reverse light stopped working. After some investigation it was narrowed down to a duff relay. This was changed and the heater fan, radiator fan etc worked again...

2. The rear boot popper stopped working the same time I changed the relay. The idling problem also started at this time.

Any possible relation? Is there anything electrical cthat could be affecting the idle that would be influenced by the boot popper / fan relay?

 

I had similar problems with my frst, i tracked it down to the throttle body, 10 years of crap built up in the base idle screw, i removed throttle & then removed the base idle screw from the throttle.
Soaked the throttle in petrol (any cleaning spirit will do) for a few hours, cleaned the screw up (even used a bit of T-cut on it) & cleaned the base idle hole with petrol & a pipe cleaner.
Look it up in your haynes manual before you remove the throttle, you've got to do something to set the idle afterwards & i can't remember what it is.