missfire#1 cyl.

345

Asked by Jun 14, 2011 at 01:34 AM about the 1992 Pontiac Grand Prix 2 Dr GT Coupe

Question type: Maintenance & Repair

92 grand prix 3.4l missfire #1 90psi all other cyl range 140-150psi i did a leak down and all cyl. were 10-15% even #1 no  indication of blown head gasket. pulled the head and looking at the valves in all cyl. they seam to be burning equal in all cyl.  pluges look good as well.pluges and wires are new fuel is not bad, no water or fuel in the oil. the cyl. has no scare or scrape either. pulled the piston and no broke or stuck rings. so why do I have a missfire and low compression on #1.  before you answer 1&4 share the same coil for ignition and #4 is fine. pluse no codes.

2 Answers

365

Well im gonna be honest. If you have the means to do so. Sell that car ASAP! That 3.4L LQ1 is a time bomb waiting to go off. either that or replace the engine with a 3.1. Head gaskets are alot cheaper than motors

345

thanks for the input. I finally pulled the head and come to find out the cylander is coned. which explanes bad compression but good leak down and excessive crankcase pressure.

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