Hello does your scan tool read live engine data? It sounds like you probably have a vacuum leak somewhere. Or an input such as the power steering switch or a charging system issue can also cause a high idle, due to the extra loads those put on the engine.
but the first thing I would check is the live engine data on the scan tool, and look for the Long Term and Short Term Fuel Trims (LTFT and STFT). If the percentage is positive such as above 10%+ you can then raise the rpm to about 1500-2000rpm and you should see that Fuel Trim number come down towards 0% or at least below 10%. That indicates a vacuum leak, If it is a vacuum leak, the best way to find it is using a smoke machine on the intake manifold, its the quickest and safest way to find a leak,
You can also try unplugging the Purge valve, if it is stuck wide open and the ECM has no control over it, its basically a vacuum leak as well.
In scan data also check the Engine Coolant temperature sensor readings, this vehicle has two of them according to the wiring diagrams, one might be for the Clusters gauge and the other for the ECM.
Try unplugging the Power Steering Pressure switch too, its on the power steering line, its a 2 wire connector, if the idle comes down, (it may take a minute) but you'll know thats causing the high idle.
Ill put up a picture of the power steering switch and Purge valve locations
https://www.2carpros.com/articles/automotive-engine-vacuum-leak-symptoms
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
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Wednesday, September 11th, 2024 AT 2:45 PM
