Just did a head gasket job all new wires and plugs.and replaced coil packs and new fuel filter and checked fuel pressure and all is good and to spec and cleaned the maf sensor..changed num 3 and num 2 sparkplug and now its reading misfire num 1..we need help with this one..we are stumped.
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1999 Pontiac Firebird Question: My firebird keeps reading po303 and jumps from po302 and po301
Answer #1pushrod May 06, 2013, 20:41Master
Is it actually misfiring or the ecm just thinks so? 3.8 or 5.7?? Compression, injector pulse, vacuum leak, you say spark ok right?
ReplyBEHEMOTH99, May 07, 2013, 06:01Rookie
Its a 3.8 v6.spark is ok and no leaks we have found yet..and compression is ok it was throwing this coode before the head gasket change so the problem was there before we even touched it.
Replypushrod, May 07, 2013, 06:46Master
When it started is irrelevant, is it missing on those cylinders? Running rough, idling rough? Forget about codes for now! Get to them later.
ReplyBEHEMOTH99, May 07, 2013, 09:43Rookie
Very slight rough idle..we took the num3 wire off to see if it would be worse of a idle and the car started and then just died..is there any way ro test the ecm thats under the coil packs.