PLEASE help me fix my rough idle!

TapouT

Well-Known Member
Joined
Oct 5, 2008
Location
Hickory nc
I'm at my wits end with my Jeep. It has no check engine light on whatsoever. It's a 1998 Jeep Grand Cherokee with the 5.2l v8 (166,500 miles). It has a rough idle and stumble when starting that I can't seem to fix. When cold starting it in the mornings it will crank and fire but when it's starting up the motor just had a dead miss like it wants to shut off but then it revs itself up and will stay running. It doesn't do this when the motor's warm it will start right up no problem. I've replaced the plugs, wires, distributor cap and rotor button, idle air control motor, air filter. I've cleaned the throttle body. I run premium gasoline in it.

It was cutting off on me one day last month and kept doing it and finally threw a code for crankshaft/camshaft sensor and I put a new crankshaft position sensor in and it fixed that problem but I still have a rough idle and am getting horrible gas mileage. It has Champion spark plugs that are gapped to stock specs, Bosch wires, BWD distributor cap and rotor button, k&n cold air intake. What else could it be? It doesn't miss at all while driving but when stopped it just has a pretty rough idle. It has a 3" lift and 31/10.50/15 All terrains and I know it will never get what is considered GOOD gas mileage but I feel like it should be a lot better than it is now. I hate to do this but I'm begging for help. Thank you!
 
My 95 ZJ did that and replacing the catalytic converter fixed it.
 
That was the only sign that mine had. Rattled around alot at idle, and occasionally when slowing down. Sometimes when I floored it, it would seem underpowered, and other times you could almost hear the clump of junk move out of the way and all the power just opened up.
 
That's how mine is. At idle it rattles like crazy and has been getting worse and worse. Maybe this is my problem?! Even if putting a new one on doesn't fix the idle issue it'll at least spare me from having to hear the cat rattle which is very annoying I might add.
 
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