P0303 cylinder 3 misfire code

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Jan 20, 2009 | 10:09 AM

Pulse_GTO

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P0303 cylinder 3 misfire code

The car is a stock 2001 Z28 with an SLP lid. The car owner changed plugs to TR6 so that he could run a shot of nitrous. As soon as he completed the plug swap the car started to misfire. We swapped plugs back, got new wires, swapped coils around, pulled the valve cover and the springs and rockers looked fine. It only misfires at idle, while driving under a load there are 0 misfires in the HPTuners scanner. What could this be???

Jan 22, 2009 | 12:42 PM

Pulse_GTO

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The owner figured out what it was. He cross threaded the plug causing it to not seat completely. He wrapped the plug with Teflon tape to test the theory out, and the misfires went away.

Jan 22, 2009 | 01:22 PM

ss.slp.ls1

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From: Orange County, CA

Quote:

Originally Posted by Pulse_GTO

The owner figured out what it was. He cross threaded the plug causing it to not seat completely. He wrapped the plug with Teflon tape to test the theory out, and the misfires went away.

That sucks, hopefully he doesn't blow it out. I blew out a spark plug after a shop crossthreaded one of my spark plugs. It started as a faint ticking noise, then a week later...bang bang bang and a cylinder 7 missfire.

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