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LS1 swap in Porsche backfire need help

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Old 01-23-2010, 11:30 PM   #1
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Default LS1 swap in Porsche backfire need help

I am wrapping up my LS1 swap into a Porsche 944 Turbo. On the dyno today we are having a backfire at 4500 rpm's.

The car idles & runs well but at 4500 we get the backfire. On the dyno o2 was 12 to 1 at WOT so it shouldn’t be a tuning issue. I was told to check for bad grounds. Any ideas?
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Old 01-24-2010, 12:34 AM   #2
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Ignition coil breaking down, spark plug wire.

I bet its not a bad distributor cap!
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Old 01-24-2010, 08:03 AM   #3
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+1 on spark plug wires.
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Old 01-24-2010, 11:50 AM   #4
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Backfire through the exhaust or intake?
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Old 01-24-2010, 12:30 PM   #5
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What about a bad valve spring? If it is broken near the bottom end it might not present itself until higher rpms.
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Old 01-24-2010, 05:30 PM   #6
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We installed brand new wires & valve springs.
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Old 01-24-2010, 05:38 PM   #7
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Maybe you have a bad fuel injector? What about your fuel and timing tables. Something could be goofed up there?
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1992, 4500, 944, backfire, backfires, backfiring, bad, bumper, causing, coil, conversion, front, ls1, ls2, porsche, s2, spoiler, swap

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