High RPM within minutes of starting

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FXJIM

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Joined
Jun 3, 2023
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4
Location
Lakeland Florida
95 4cyl, just bought it but when it’s cold starts good with 1000 rpm but within minutes the idle rpm rises to around 1500 rpm. Throttle cable is adjusted correctly. Any ideas what this problem might be.
 
Id start with pulling the Idle air control, cleaning the port and probably installing a new IAC. Once installed typically one will have already disconnected the neg on the battery and let your jeep it sit with the battery disco'ed for a couple hours. The ecm needs to be "reset" so to say.
 
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Gilaguy23 said:
Id start with pulling the Idle air control, cleaning the port and probably installing a new IAC. Once installed typically one will have already disconnected the neg on the battery and let your jeep it sit with the battery disco'ed for a couple hours. The ecm needs to be "reset" so to say.
Click to expand...
^^This.^^

Also you might want to check for vacuum leaks.
With the engine running, spray the a little carb cleaner on each vacuum connection listen for change in rpm.
Also grab each connection and give it a wiggle, again listen for changes in rpm.
Replace any vacuum hoses that are questionable. Replace any damaged vacuum ports.
That's a good start.
 
Inspect for vacuum leaks as described above. If the IAC has failed it should throw a trouble code but not always. Sometimes it wont' unless it's completely failed. Checking for vacuum leaks is free and there are plenty of places for vacuum leaks to happen.
 
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