Hey folks,

Here's the rundown. Ill be in the US Navy in a few months
and I need to get my car buttoned up, and worry free for
my return.

My car pings in 3rd and beyond @ WOT. 350 with 081 58cc
305 heads and a mild single pattern cam. Yes, I know im already
prone to detonation due to compression.. However, the engine initially
had no detonation whatsoever! I inherited this problem from somewhere.

I think its converter lockup causing the problem, but the tranny
is stock. I unplug the 4prong at the trans and the ping is gone.
The car pulls like a bat out of hell through all 4 gears.

Other than backing some timing out of the tune, I dont know
what else I could possibly look for?

Ill be running a few tests this weekend with some toluene
in the fuel with the 4prong connected at the trans, if the
detonation is gone, then.. I guess 91octane aint gunna suffice.


Where else could I look? Anyone else in the same boat?

 

Nobody has a diagnosis huh?

I can easily drive the car around with the 4prong disconnected
at the trans and have my foot in the floor all day with no ping..

But, no peace of mind...

 

I had what sounded like detonation happening in 3rd gear at 35 mph but not in 4th gear above 45 mph.....Turned out I had some bolts loose on the torque converter. The car would also hunt back and forth in 3rd at 35 but not in 4th at 45+ mph. Tightening up those bolts solved the problem.

 

I find the OD extremely annoying. It lugs the engine. It should NOT go on at WOT but sometimes it does, this lugging I believe is causing your detonation as you said. I rigged a switch off of my brake pedal wire to turn the OD on/off, this might work for you.

 

Thanks Reid and Rayzor for the input, Ill check the TQ converter bolts.

It is rather annoying because everything else is operating correctly.
So, to have this trouble is a head scratcher at best! My shop Arizona TPI,
echoed the same feelings but, of course they wont do anything unless they
get the car on computer monitor.

I pray boosting the octane will net some sort of improvement.

Rayzor, was the OD switch install more playing prevent or is it
a viable performance mod? Im curious and sounds easy enough.

 

I don't like my OD kicking in around town or when I hit WOT, I only use it for highway cruise so I rigged a switch so I control when it goes to OD. If you look by the brake pedal you will see the switch with a pink and white wire coming out of it IIRC. Splice a switch inline with the pink wire and mount it under the dash.

 

Hell, its worth a try!
And, Im with you.. I hate when OD hinders my streetability.

Ill give it go, and post up results.