» » »

Pontiac Q&A

Ask Your Question

1999 Pontiac Firebird Question: My firebird keeps reading po303 and jumps from po302 and po301

 

Question

BEHEMOTH99, Potwin, KS, May 06, 2013, 17:19
 Rookie

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.

1 Answer
Flag This
  • Answer #1

    pushrod May 06, 2013, 20:41
    Profile_thumbnail
     Master

    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?

    Flag This
  • Reply

    BEHEMOTH99, May 07, 2013, 06:01
     Rookie

    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.

    Flag This
  • Reply

    pushrod, May 07, 2013, 06:46
    Profile_thumbnail
     Master

    When it started is irrelevant, is it missing on those cylinders? Running rough, idling rough? Forget about codes for now! Get to them later.

    Flag This
  • Reply

    BEHEMOTH99, May 07, 2013, 09:43
     Rookie

    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.

    Reply
    Flag This