ZJ Rough Idle at startup and goes away after a minute

ronin

New Member
Joined
Jun 16, 2023
Messages
1
Location
Mohegan Lake, NY
I have a ‘98 ZJ with the 4.0L. The last few weeks I noticed a rough idle approximately 30 seconds after startup.

During this time, the RPMs drop to 1100 and putting my foot on the accelerator has no effect. The rough idle stays for about 20 seconds and then goes back to normal 1600.

The rest of the time the car is on, I never experience it again - truck drives normally. I changed the IAC and it hasn’t had an effect on the issue. No CEL or codes presented during rough idle. O2 sensors were replaced 2 years ago.

Appreciate any thoughts on this. Thanks.