It sounds like you have heavy carbon buildup on the valves. Do you use cheap gas? If so switch to a good brand. Go to an auto parts store and grab a bottle of seafoam, and dump it in the tank before filling up. Then go to the dealership and grab a bottle of Chrysler combustion chamber cleaner. Follow the directions carefully. It is sprayed directly into the throttle body. I always let it sit for several hours before restarting to really let it soak in. It may take more than one round of treatments, but this worked for me, as I dealt with the issue as well.

 

I just actually just decarbed it last Friday. My buddy works for B&G . he has a fogger system we hooked up and sprayed treatment into the throttle body. It takes about 20 minutes with the engine running. It blew out some serious carbon. It sounds the same as it did before. I filled it up with 89 getgo gas which I've heard they get gas cheap cause gas has a shelf life and they mix the old with the new, could be an urban legend I don't know.

 

Other than what has already been said by others...

Last thing I can think of would be possible hairline crack or small hole in the egr tube. That could give you the odd diesel sound and pinging if its not operating properly.

 

All great info thank you guys I will check my exhaust better tomorrow and get better gas and look at my egr and see what happens.

 

Also, many areas switch to winter blends, which are known to cause detonation.

 

Thanks "ryan0260" you may be the smartest and most helpful person on this forum.

 

What year is this JK? (ie: What motor - 3.6 or 3.8?)

 

07 6speed, 55 thousand miles on it

 

I would still try the CCC. The problem with the fogger treatment is that it doesn't give much time for the product to soak in. Something else that plays into carbon buildup is how you drive it. The problem I was having is partly due to the fact that my JK makes short, frequent trips. I don't drive it enough to keep things clean. If this is you, don't be afraid to take it on a good long drive at highway speeds, and get on it pretty hard from time to time. It will help keep it cleaned out.

 

Your right about the fogger its in and out cause while its spraying the engine is sucking it in and right out the tailpipe. It may remove some superficial carbon but not the heavier deposits. And yes I do only drive my jeep about 50 miles a week. I'm gunna try that ccc and some better gas then go on a long drive. What's better gas Exxon, BP, or sunoco?