Chasing detonation!
#1
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Car: '89 Trans AM/'88 GTA
Engine: (2) Tuned Port L98's
Chasing detonation!
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?
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?
#2
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Car: '89 Trans AM/'88 GTA
Engine: (2) Tuned Port L98's
Re: Chasing detonation!
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...
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Car: 1989 GTA
Engine: SuperRam 350
Transmission: Pro Built S/S TH700R4
Axle/Gears: 3.27
Re: Chasing detonation!
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.
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Car: '89 IROC-Z
Engine: 355
Transmission: 700r4 edge 3000 stall
Axle/Gears: 9-bolt 3.73
Re: Chasing detonation!
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.
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Car: '89 Trans AM/'88 GTA
Engine: (2) Tuned Port L98's
Re: Chasing detonation!
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.
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Car: '89 IROC-Z
Engine: 355
Transmission: 700r4 edge 3000 stall
Axle/Gears: 9-bolt 3.73
Re: Chasing detonation!
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.
#7
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Car: '89 Trans AM/'88 GTA
Engine: (2) Tuned Port L98's
Re: Chasing detonation!
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.
And, Im with you.. I hate when OD hinders my streetability.
Ill give it go, and post up results.
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