Does the motor consume oil? If it does I would change the pcv valve and go with a thicker oil. Then you will need to work on the carbon deposits. Don't waste your time with seafoam. Go with something stronger like Mopar combustion chamber cleaner. You may have to do more than one treatment. You spray the can directly into the throttle body until empty, and shut off the engine and let it sit so the product can soak in to break up the deposits. I highly recommend allowing it to sit much longer than it says in the directions to give it more time to work. When you drive it afterwords run it kind of hard to blow everything out and then change the oil.

 

My 11' JKUR on 87 w/ about 27k miles pings going up steep hills. 89 seems to cure it, I only put in 89 when I know I'll be doing some hills.

 

Thanks for all the input. To answer some queries. I bought the unit 2 years ago used from a jeep dealer. It had one previous owner that NEVER took it off road. Totally bone stock factory. It only has 84,000kms on it (approx. 52,000 miles) so its a low mileage unit. It does consume about half a quart between oil changes. I have recently changed the PCV valve as well as plugs and air filter. The seafoam really smoked the place out last night, so I know I have carbon buildup (likely from the oil consumption.) I have read other threads suggesting 5W 30 oil as opposed to the 5w20 I currently run to reduce oil consumption. I may try that next oil change.

I tried to run Ronjenx's procedure for retrieving codes, but it doesn't seem to want to cooperate. I'll take it to the shop and get them to pull any codes for me. In the mean time, I have driven a friends 07 JKU and it runs wwaaaaayyyyy smoother than mine with almost 3 times the mileage. I'm starting to think I might have a faulty plug or plug wires as the engine is super sluggish and runs somewhat rough with knocking/pinging.

Thanks to all you guys for your input. Gonna try the thicker oil, new plugs and wires and see where that leads.

Cheers!

 

The computer is trying to eliminate the pinging by retarding the timing. It's still pinging so the timing must be retarded to the max, which would explain the sluggishness. That's assuming the knock sensor is doing its job.
If it's pinging because the knock sensor isn't working, well, knocking/pinging will make it sluggish, too.

As mentioned above, try higher octane gasoline. I would go right to the highest you can get just to test it.
That may work, but you should still find the reason for the pinging.

 

Thanks Ron, I just filled her with 91 octane from Chevron, with that Techron additive. I'll let you know

 

That should take care of it, or at least lessen it. Before you invest money on new plugs, wires, knock sensor etc, I would start with a good $10 can of CCC, and go from there.

 

I'll do that first then. Drove it on the highway this afternoon. With the 91 Octane. Substantially less noticeable

 

It really should help. You can also run a bottle of seafoam through the tank. Run it kind of hard after the treatment, then change the oil. May be a good time to switch to 5w30.