1994 Pontiac Bonneville sustained pre-ignition

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Computer problem
1994 Pontiac Bonneville 6 cyl Front Wheel Drive Automatic 228000 miles

long story ill make as short as I can. Bought a bad running 94 bonneville ssei supercharged 3.8, replaced motor, motor ran well at first but once I ran the car hard it missed badly, pulled plugs, brand new auto light app 606 had one electrode melted off, replaced plug car ran well. Again ran car hard, car started knocking, again replaced engine. Car ran well untill the super charger kicks in or any time above zero on boost gauge, had 3 more melted plugs. Replaced plugs added a bottle of octane boost. Ran hard, blew it up, severe pinging cylinders 1 and 5 at 30lbs compression. Tore down the original engine it had a hole in cylinder 5 piston, and motor had new pistons and a fresh rebore. Two different engines two different super chargers used all sensors from the donar engines. Car is using 91 octane gas, only thing I re used was the coil packs which had been tested at local gm dealer when trouble started. This has to be the car. Computer? Ignition? I have changed the computer but reused the prom chip from original. All the trouble seems to occur once the boost gauge climbs on to the plus zero side of the gauge car idles at minus ten any help greatly appreciated currently engine at machine shop getting new piston and rehone done to the original engine. Dont want to blow up another one.

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have the same problem?
Thursday, November 26th, 2009 AT 6:44 PM

1 Reply

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Are you sure you don't have the wrong plugs in the vehicle? Too hot?

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Wednesday, December 16th, 2009 AT 8:15 AM

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