View Full Version : LS1 swap in Porsche backfire need help

01-24-2010, 12:30 AM
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?

01-24-2010, 01:34 AM
Ignition coil breaking down, spark plug wire.

I bet its not a bad distributor cap! :D

01-24-2010, 09:03 AM
+1 on spark plug wires.

01-24-2010, 12:50 PM
Backfire through the exhaust or intake?

01-24-2010, 01:30 PM
What about a bad valve spring? If it is broken near the bottom end it might not present itself until higher rpms.

01-24-2010, 06:30 PM
We installed brand new wires & valve springs.

01-24-2010, 06:38 PM
Maybe you have a bad fuel injector? What about your fuel and timing tables. Something could be goofed up there?