Car Questions
RepairPal is your advocate for car care advice and guidance

My firebird keeps reading po303 and jumps from po302 and po301

(1999 Pontiac Firebird)
in Potwin, KS on May 06, 2013
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.
Displaying 1 answers & 3 comments
Popular Answer
on May 06, 2013
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?
on May 07, 2013
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.
on May 07, 2013
When it started is irrelevant, is it missing on those cylinders? Running rough, idling rough? Forget about codes for now! Get to them later.
on May 07, 2013
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 there any way ro test the ecm thats under the coil packs.
RepairPal estimates are guaranteed at over 2,000 quality certified locations nationwide. Learn more

Similar Questions

View answers to similar questions from RepairPal's community of auto experts and enthusiasts.
At first my heater only used to work (6 years ago). But after I've put a new engine(last year)in my heater just kind ...
Turns over, sounds mostly normal, maybe a little slower than normal, but not much. Lights on dash light up. Fuel pump...
Didn't find what you were looking for?