Black06onvert

I have an O6 GT convertable. Im getting a bad knock and check engine flashes under WOT in 3rd gear. I ran a DCT scan and it gave me a P0300/ Miscellaneous misfire code. Btw I have a JLT cai along with sct program. Iv been running the program about 5 month but jus started with this issue. Also Im running the 91 program and always run 91 plus a octane booster. Wolud love any input. Thanks..

adj86

Stop using the octane booster, and try running a can of seafoam through the tank, see if that helps any at all. Might be time to pull the plugs and take a look at em. Sounds like it might be too late for seafoam help. Are you getting a code for a particular plug/cylinder.

Also check this out.

http://www.obd-codes.com/p0300

BigDinTexas

Maybe bad tank of gas? Did you get this gas from the same place you normally do? Are you running the appropriate octane for the tune? What if you change the tune to one that is less aggressive? Does the knock remain?

Don

siggyfreud

Octane booster stuff is usually a no go for cars with CATS btw. Might also foul up your oxygen sensors.

adj86

+1

I think I've also read that stuff can really foul up the plugs as well. OP do you always use the octane booster on every fill up? Try using a higher grade of fuel w/o octane booster. How long has the problem persisted?

Lifter583

I would be changing the spark plugs to begin with...
+1 on the Seafoam and NEVER oct booster...