In traffic lights will idles high increasing at about 2,500 RPMs?

MAURICETTY

MEMBER
1998 ISUZU TROOPER

When driving in traffic or stopping in traffic lights will idles high increasing at about 2,500 RPMs. I have changed the IAC, have the ECU checked inspect the vacuum hose but it still continues to happen. Whenever it happens I would stop the vehicle disconnect the battery pole after a few seconds reconnect and it will idle normal again. Whenever I put the vehicle off and start it again the rev will speed up again. Can you help me find the problem?

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,
It sounds like the idle need to be reset as there is no adjustment for the engine idle speed, it is controlled by the ECM.

Try this reset / idle learning process:

Remove the fuse for the ECM. That fuse is located in the fuse box under the driver side dash. It should be the number C9 and a 15A fuse.
Try to start the engine for 5 seconds then stop. The engine will not start because the ECM fuse is out.
Turn the key off.
Put back the ruse for the ECM.
Turn the key to the on position (do not start).
Push slowly to the accelerator pedal all the way to the floor or end of its travel and release slowly.
Repeat this process for at five times.
Turn the key to the off position.
This should reset the idle speed.

Please let me know of any questions.
Thank you.

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