ok my car idles high when its warm at about 1200-1300 rpm when its cold it idles at about 900. its not an intake leak cuz ive sprayed the intake w/ carb cleaner several times and notihng happened. could my ACT or coolant temp sensor be bad? or do you guys have any other opinions?

also would a bad ACT or coolant temp sensor hurt my gas mileage? i used to get 20mpg and now i get 15/16mpg thanx everyone

 

sounds like the coolant temp sensor. it will make the car run rich.

 

really? cool. i guess ill just replace them both then

 

Ask the brain making the decisions for A/F and spark advance, check the system for ACT or ECT failure codes. If the system sees they are within specifications, why fix/replace something that is not broken........ DIY KOEO/KOER/Cylinder Balance Self-Test

 

to test thoes i need to do a KOER test correct? would i have a CEL if they were bad? cuz the CEL is not on.

 

The system is in a continuous self-test mode always, in the event of a failure, it will be logged in memory (2nd. set of codes in a KOEO). A KOER will test the system real-time during its execution only.