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HELP please, MISSFIRE, I Searched Posts.
Ok, Heres the story...
Last year I came across this board before buying my 99 firebird. I just want to say that this is a wealth of information...
Well, shortly after I purchased the car, I had a missfire, changed one coil and went away...
Now, I have a very bad missfire... heres what I have done.
I replaced all the spark plugs and spark plug wires with Bosch Plugs and wires. 7.5 mm I think... I replaced all the heat sheilds in doing so.
Still has a missfire, Autozone scanned, showing P0303 and a P0300... Just to be sure I had them clear the codes, (incase it was from a bad plug/wire on cyl 3)
Well, Now im getting just p0300... Random cyl missfire. I replaced all three coil packs and still a miss. I pulled the module off and autozone run a test on it, stated it was good... They also mentioned that the ICM goes bad and car wont start at all, or stalls out and dies...
Well, put that bad boy back on, replaced the fuel filter and Checked the fuel pressure and was about 50-52 pounds... Good... So then Still missing. bad...
this whole missfire started weeks ago as a very intermittent problem and only has gotten worse. It would only miss a bit at WOT. Then more often going up hills, to ALL THE TIME.
I have good Fuel Pressure...
I have good spare on all cyl... Blue color...
I have Replaced coils, plugs and wires...
I am thinking that probably the Crank Position sensor is out... But autozone (3 of them) say that if those are out, it would be a no start/stall condition...
Oh, I also checked for head gasket issues... Looked for coolant in oil, none. looked for oil in coolant. none. looked for moisture at the exhaust... None.
Oh, and today, i ran the seafoam thru the vaccuum line... Still, hasnt gotten any better.
I also checked and cleaned the terminals on the ICM...
What should I do? Please and thanks in advance.
Last year I came across this board before buying my 99 firebird. I just want to say that this is a wealth of information...
Well, shortly after I purchased the car, I had a missfire, changed one coil and went away...
Now, I have a very bad missfire... heres what I have done.
I replaced all the spark plugs and spark plug wires with Bosch Plugs and wires. 7.5 mm I think... I replaced all the heat sheilds in doing so.
Still has a missfire, Autozone scanned, showing P0303 and a P0300... Just to be sure I had them clear the codes, (incase it was from a bad plug/wire on cyl 3)
Well, Now im getting just p0300... Random cyl missfire. I replaced all three coil packs and still a miss. I pulled the module off and autozone run a test on it, stated it was good... They also mentioned that the ICM goes bad and car wont start at all, or stalls out and dies...
Well, put that bad boy back on, replaced the fuel filter and Checked the fuel pressure and was about 50-52 pounds... Good... So then Still missing. bad...
this whole missfire started weeks ago as a very intermittent problem and only has gotten worse. It would only miss a bit at WOT. Then more often going up hills, to ALL THE TIME.
I have good Fuel Pressure...
I have good spare on all cyl... Blue color...
I have Replaced coils, plugs and wires...
I am thinking that probably the Crank Position sensor is out... But autozone (3 of them) say that if those are out, it would be a no start/stall condition...
Oh, I also checked for head gasket issues... Looked for coolant in oil, none. looked for oil in coolant. none. looked for moisture at the exhaust... None.
Oh, and today, i ran the seafoam thru the vaccuum line... Still, hasnt gotten any better.
I also checked and cleaned the terminals on the ICM...
What should I do? Please and thanks in advance.
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