2008 JK Pinging in top gears

[karldiaz]

Hi,, I own a JK sports unlimited 2009 model automatic wrangler. same issue with pinging noise. i have always used 98. i have complained to jeep and they said change your fuel station. can anyone help?? any mechanic?
I bought this brand new and never used anything other than 98.

[Elio S]

Pinging is pre ignition. Pre ignition is often caused by advanced timing and/or high compression. It often shows up in an engine after you've had the head/s machined. Since timing is non adjustable on the JK and I highly doubt any of you have had head work done yet I can only assume the pinging issue is being cause by carbon build up in the cylinders or your engines have a hot spot in them. Carbon build up could be caused by frequent short trips and stop start city driving. Everytime I service my vehicle I spray a can of Subaru upper engine cleaner into the intake. It cleans up all the crap in the intake manifold and cylinder heads. The differance in perfomance is noteable. Only other thing is as somebody has already mentioned, is spark plug gap. You shouldn't have to adjust the gap as spark plugs are set from the factory, but it might be worth trying to find out if somebody has fitted the incorrect spark plugs to your cars. Hope this may help.
Also, I might add, as somebody who's job it is to attend stranded motorists on a daily basis, I have seen several incidents of e10 petrol fouling up spark plugs on modern engines, even ones that supposedly were designed to run on it. The way I see it, if it's not good enough for my lawn mower, I'm certainly not putting it in my car. My GC runs fine on standard 91 octane unleaded.