idles too high when warm and too slow when cold..

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idles too high when warm and too slow when cold..

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idles too high when warm and too slow when cold.. - 1/17/2005 8:38:40 PM

chuck322

Posts: 8
Joined: 4/25/2004
From: Canada
Status: offline

my 84 5000 S starts well, but wants to idle when cold around 400/500 RPM which i think is too slow when cold. when engine is at operating temp, in Park it will idle at around 1100/1200 RPM. this seems backwards. do i have a vacum leak. or defective cold start valve??

Post #: 1

RE: idles too high when warm and too slow when cold.. - 1/18/2005 10:47:01 AM

0fframp

Posts: 758
Joined: 3/9/2004
From: Swamplands of NJ
Status: offline

Since you are in Canada I am not sure which engine management you have but here are some ideas. Check the cold start circuit. On my 84 4000S I had a similar problem that turned out to be corroded contacts on the coolant temperature sender (not the gauge sender). The auxiliary air valve or idle stabilizer valve (ISV) could also be a problem, check to make sure that it works. The ISV relies on a micro switch on the throttle to tell the ECU when it is supposed to be idling. This switch either breaks or gets corroded bypassing the ISV circuit. Another culprit on older cars was the warm up regulator that provides cold enrichment. On cars with ISV valve there is no warm up regulator but a differential pressure regulator mounted on the fuel distributor. This too can wear or the wiring could break.

(in reply to chuck322)

Post #: 2