"Dave Gee" > wrote:

>Hi group:
>
>I have a problem with my '89 L98, it does not run right untill the coolant
>temp. gets up to about 150. Before it gets to this temp it stumbles and
>idles low (sometimes dies) after it reaches temp. it runes fine. If it had
>a carb I would think the auto choke was not working, the symptoms are very
>like that condition. I have heard about closed/open loop transitions with
>the on board engine management, could this be the problem? any diagnostic
>ideas welcomed, I am wondering where to start to track the problem down.
>
>TIA Dave G.
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Hi Dave,

It sounds as if your coolant temperature sensor has gone out of
calibration. Have someone scan your computer data stream with the car off and
cold, and see if the temp sensor is giving the ECM readings as if the car was
already warmed up. If it's out of calibration, the ECM should catch it when you
start the car cold--it compares the coolant sensor readings and the intake air
temp readings--they should be within a couple of degrees of each other with a
cold engine. You didn't mention if the "service engine" light was lit or not--If
the ECM caught the difference in cold readings, it should illuminate the lamp.


RON
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