"louder muffler and turn up the radio" - LOL!!!!! Absolutely the NEXT thing on the agenda.

And as far as why changing the oil may help - others are far more versed in the science than I am - but since I first started driving in the 70's, I've always been told the viscosity of 10w 30 is much more suited to the hot weather we have here. 5w 20 is apparently a great oil for engines in colder climates, but we need a higher viscosity in higher heat I'm assuming because it leaves a thicker layer, longer, as the temps inside the mechanical bits heat up.

Either way - like you said - it can't hurt huh?

Just a quick note on the in-line six 4.0L - when I traded off my last 4.0L, it had 147,000 miles on it and I had just returned from a trip to Colorado where I averaged about 75 or 80mph the whole way - I got 22mpg. The best I've ever gotten from the either the 3.6 or the 3.8L - no better than 19mpg downhill with a tailwind! Now THAT'S progress And I'm off the soapbox now -

 

Try a carbon buildup treatment for the spark knock, and try a thicker oil for the consumption.

 

I have dealt with this problem on my '08 JKU 6 speed for over two years! I have tried different octanes and all types of additives, Lucas oil treatment seemed to help for awhile but it back to the rattle. If I my shift points are around 3000 RPM's it helps a bit also but if its under load it sounds like a diesel.
I haven't tried a heavier oil yet but it's on my to do list! I personally feel with mine it's the 3.21 gears and the 255/75/70 tires, I'm about re-gear with 4.56's and 35's I'm hoping it'll take care of the problem.

 

SUCCESS!!!!!!

The combustion chamber cleaner seemed to work - - no knock so far - and damn that stuff stinks - but now my check engine light stays on - I HATE COMPUTERS!

 

Have you checked for a broken heat shield or a cracked header? these were a prevalent problem for a lot of guys on the site... i myself have "removed" the heatshield that was rattling something terrible. The part that grabbed my attention was when you said "sounds like a diesel under load"

 

It probably got pissed when you were spraying and had the MAF with no air. unhook the battery, tap the brake, and see if the light comes back. IF it does check the code and see what it is.

Search if you don't know how i cant remember its turn key on off blah blah blah...

 

Glad to hear it helped you. I'm not sure why your check engine light is on though. I didn't have that issue.

 

Ryan thanks for your advice - and I suspect Tweak is correct - I could disconnect either end of the air hose so of course I chose the one that was easiest - the one closest to the air box. As I was spraying the fluid I kept wondering what the wires were that were connected into the air hose closer to the intake (did I mention the average 8 year old knows more about the new engines than I do?). I've since learned I sprayed a whole can of cleaner right into the Mass Air Flow sensor - I'm guessing I screwed it up - but hey, no more knock! I was a bit disappointed at the lack of smoke coming out the exhaust though - kinda hoping to fog the mosquitoes.....

Now that I've conquered the knock (with y'alls help) I'm off to the store for a lift kit and new tires!!!!!!!!!

 

Good deal. Fyi , the best way to use the CCC is to remove the intake tube and spray it directly into the throttle body. It helps to have someone inside the vehicle to keep the engine running while contents are sprayed.

 

That sensor is the intake air temp probe. Not sure how sensitive they are to solvents. When I used the CCC I sprayed directly at the butterfly and did get the engine light for about 30 seconds but it went away before the can was emptied.