I have a 97 4.6. I think I'm having a detonation issue. Its an erratic rattling noise on hard accelerator. at high rpm or anytime the engine is under a heavy load. I know the main causes are egr system, fuel/air mixture, carbon build up, high temp., and knock sensor. It's not throwing any codes. I was thinking that any of those issues would throw a code or two. Before I do a tune up (plugs, fuel/air filter. etc..) can there be detonation issues without codes and is there any other possible issues that sound like detonation? thanks.

 

I have a 96 F-150 with the 4.9 (IL6) bought a year ago and it did all that .No codes. A full tune up (plugs, wires, air filter, oil change w/filter, plugs, wires, dist. cap, rotor button, fuel filter and pcv) solved the problem. Fixed detonation,missing etc. Ran great afterwards..It threw no CEL codes ..

 

All I've had time for so far was the fuel and air filter. Seems to have made it better but I can still hear a little. MAF checked out good. Sprayed it with some cleaner. Going to run a tank of premium through it to may be help with some carbon build up. Plugs are next on the list.