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Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 13755
Experience:  Jeep Certified Master Tech
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Jeep commanchee: On engine start up it runs at a very high

Customer Question

On engine start up it runs at a very high RPM and takes about 2-3 minutes to drop down to idle speed. I have been told this is caused by electronic control unit but cannot find any info on it if it is the problem. need to define problem and then formulate repair plan
Submitted: 2 years ago.
Category: Jeep
Expert:  Chris replied 2 years ago.
Hello, my name is***** you for allowing me to assist you! This can be caused by 1 a vacuum leak (split line/hose, etc. 2 a sluggish Idle air control motor, or 3 a TPS (Throttle Position Sensor) that is failing and telling the PCM (engine computer) that the throttle is open more than it really is. Which engine do you have in your Comanche?
Customer: replied 2 years ago.
4.0 gas
Expert:  Chris replied 2 years ago.
Ok, thanks. I do see issues with the TPS on these engines, and if you find no vacuum leaks, I recommend replacing it first. If the problem continues, then replace the Idle Air Control motor. Both are mounted on the throttle body. If you need the procedure on how to replace the TPS, let me know and I will send it to you.