'04 Silverado 5.3L Detonation

[emag]

Hi Everybody-
I have a 2004 Silverado with the 5.3 liter engine. It has given me 89,000 trouble-free miles since i bought it new, but it recently has developed an audible detonation when under full acceleration. It's only noticeable from 4000 rpm on up, and only when my foot is on the floor, which isn't very often.

I have switched from Chevron 87 octane to 89, and then to 91, yet the problem persists.

It has a fresh air filter and the O2 sensor doesn't seem to be obstructed or anything like that.

Any ideas? Thanks in advance!

[MrCritical]

Carbon build up.

[RoGuE]

I used Seafoam in my Taurus and it helped some. Some people might recommend Auto-RX, which is something you run through your oil and supposedly cleans it out.

With Seafoam, you just suck about half the bottle throuugh a vacuum line, just a little bit at a time, don't let it take it all in at once. Have someone in the car keep the engine running because it will start to die. Once it is all sucked up you shut off the car, wait ten minutes or so to let it soak, then start it up and blow the crap out the exhaust. If there is a lot of build up you should have a nice smokeshow. Be warned though, some people say this might hydrolock your engine so use at your own risk.