Erratic Idle

[fred cook]

A friend of mine just bought a 1987 924S coupe. The car is in fairly good condition, but has one weird/annoying habit of going from a normal 8-900 rpm idle to about 2000 rpm for 30-90 seconds and then back to normal. The engine seems to be running ok temp wise and the fans come on as needed. There do not appear to be any coolant or pressure leaks. Anybody got any ideas?

Thanks,

Fred Cook
'80 911SC coupe
'88 924S (in a previous life)

[Iggy]

Try the 924 forum.