High Idle / engine run-on when cold

[delibessleep]

Hi,

This may be perfectly normal.

When both the weather and engine are bone cold, my 2.1L WBX takes considerable time to idle back down after a rev up. It'll occasionally "stick" at whatever the tach read when lifting off on the throttle. After a bit (longer the colder it is outside,) the RPMs drop immediately to the desired Idle speed.

It goes away once the engine warms up, but this can't be right. It doesn't look like anything is sticking (throttle cable, armatures, etc.) Looking through some Digijet literature, I noticed the cold mixture/throttle operation is signaled by a coolant temp sensor. Is it possible this would contribute to this overrun? Or is there something else to inspect? Perhaps the throttle valve deceleration switch?

Any advice is appreciated. Thanks.
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63 Single Cab
87 Westy
18 Alltrack

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