I have been having a problem I think with my truck for a while, and was wondering if someone else had the same thing. My truck is an '01 Sierra sbsc with a 5.3 auto. When I am on my truck at WOT it has a detonation type rattle or sound between 3800-5000 rpm. If I slightly let off the throttle it goes away. All I have done is a drop in K&N filter. I have been told that it is my injectors. If anyone has any ideas all will be appreciates. And the truck at the track only ran 15.90 doing this.

 

Try changing your fuel filter first.I had this problem with my hypertech tuning and wheni changed fuel filter problem was gone.Even a slightly clogged filter will cause you to run lean at wot and cause detonation.GOOD LUCK

 

I have already done that. It has been doing it since 35,000 miles and it has 108,000 now. Thanks for the advice