Hi all,
I have a 2006 Renegade 4x4. about 85k. new plugs put in about 20k mi ago. all fresh fluids, etc. I noticed the problem when I changed the serpentine belt many miles ago, but it seemed to go away. I sat in idle for a long time yesterday to see what happened. Basically it starts with a smooth cycle, then rumble rumble, then smooth, then rumble, back and forth until i reach normal operating temp. Then it smooths out and sounds fine. I heard of people having idle problems in extreme cold temps and when spark plugs are shot, but neither of these seem to be my problem.
Any thoughts?
Thanks

oh, and as an ex Pittsburgher I feel I can wish you all a Happy Wiz Kahlifa day LOL

Have the HVAC setting on defrost or floor mode?

The AC cycling can give the engine a rough idle.

Great point! I will check this tomorrow, thanks!

Was the AC your issue? I've had a lot of problems with rough idle. First time around i got both head gaskets replaced because one was blown and I was throwing random misfire and cylinder 3 misfire codes.

Even after getting the gaskets replaced it still has the same smoooooooothrumblerumblesmooothrumblerumble as was there befrore the gasket replacement.

My AC/heater is always set to Defrost/Floor combo.

And its still thorowing random misfire codes.