Howdy folks! Well, my Trusty 94 Bonneville has just turned 170K. Had it since it rolled off the dealership lot. About 10K miles ago she started detonating under moderate to heavy acceleration. Sounds just like a bag of marbles sometimes. I have always run 89 octane, no changes. Wondering if maybe a sloppy (original) timing chain or a defective knock sensor might be at fault. Not setting any codes, still plenty of good power. I just changed out the fuel filter, plugs and air filter.

SE, SSE, SSEi? If its a supercharged engine you must run 91 only.

3800 Series 1, NA, not supercharged. Sorry- Thanks

Carbon build up on the heads?

Oh, and Welcome to the Club!

Thanks. I thought of that. Might be, but I figured FI cars control mixture a lot better than carbs, not sure if that is common or not. Leaning towards a sloppy timing chain maybe. Has anyone had any similar experience of detonation in these cars with high mileage?

Trusty, Do a SEARCH on "Timing AND Chain". You'll find a few interesting discussions on this subject.

Mine does the same. I've got my theories, but never really figured it out. Let me know what you find.

Thanks Guys, I'm inclined to think it is in fact a timing chain stretched out. I will check the knock sensor first however. I was just curious if this was an avenue anyone else had been down before. Very trusty car, it deserves whatever it needs to fix it. This car has never let me down.