High Idle Speed Fix

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SAString

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If you suddenly have a high idle speed that won't go down to normal levels, ask yourself, "Did I disconnect my battery lately?"

This had me baffled for several weeks. I replaced the IAC valve, checked for intake leaks etc. still ran too high (1500 rpm).

Apparently, disconnecting the battery wipes the computer of learned parameters. Somehow mine "re-learned" to run high RPM all the time!

I don't recall where I read the recommendation, but it worked. When the Jeep was cold, I disconnected the negative side of the battery, then turned the ignition key to crank several times to drain any residual current. After waiting a few minutes, I reconnected the battery. Then I turned on the ignition to RUN (just before crank) then OFF and back to RUN three times. While staying in run, I pressed the gas pedal to the floor and slowly back up three times, then I cranked the engine. Magic! The engine was up for a few seconds then dropped to normal levels. It's been fine ever since.

I'm not sure which of the steps above did the trick, but I'm happy with the results. Anyone else who has knowledge of this, please chime-in!
 

sparebeer

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Necroposting, but had the exact same problem, did the exact same troubleshooting, and was thinking it was an intake manifold leak. Disconnected the battery overnight and it's back to normal now, so thanks for posting this. Saved me a lot of trouble.
 

asulwer

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If you suddenly have a high idle speed that won't go down to normal levels, ask yourself, "Did I disconnect my battery lately?"

This had me baffled for several weeks. I replaced the IAC valve, checked for intake leaks etc. still ran too high (1500 rpm).

Apparently, disconnecting the battery wipes the computer of learned parameters. Somehow mine "re-learned" to run high RPM all the time!

I don't recall where I read the recommendation, but it worked. When the Jeep was cold, I disconnected the negative side of the battery, then turned the ignition key to crank several times to drain any residual current. After waiting a few minutes, I reconnected the battery. Then I turned on the ignition to RUN (just before crank) then OFF and back to RUN three times. While staying in run, I pressed the gas pedal to the floor and slowly back up three times, then I cranked the engine. Magic! The engine was up for a few seconds then dropped to normal levels. It's been fine ever since.

I'm not sure which of the steps above did the trick, but I'm happy with the results. Anyone else who has knowledge of this, please chime-in!

this was the solution after i replaced the solenoid thats connected to the valve body.
 

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