missfire at high rpm/WOT
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the problem started about a week ago when im in higher rpms at WOT the car seems to missfire. but when i drive normal it runs fine.what do you ruys think it could be.
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what are "higher rpms". for me, a bad coil wire caused a missfire at like 4k rpm. a cracked plug caused a missfire at like 5500. and with a bad coil my car started breaking up at like 5800 or so. i had a hard start with the bad coil wire as well. ive never had an opti miss at high rpms, it would just stumble at low rpms, but i know they'll mis up top too
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I had this issue not too long ago. Ran GREAT until 3rd gear at about 3000 rpm's....it would start missing for a few seconds, then clean up till I hit 5000 rpm's, then do it again. first time it happened it was the #5 plug wire grounding out on the header...
Second time it was a bad cap/rotor...
Third time it was the plug wire again...
Fourth time it was the opti going out...
Fifth time it was the plug wire AGAIN....
I just said eff it and replaced the opti, cap, and rotor with MSD opti, MSD cap/rotor, new TPiS Coil Wire, and I used the 8.5mm OTVC SP Wire setup to get them away from the headers...
Since then, no issues at all! So like Built LT1 and Wicked said...start with those culprits and go from there...Should solve the problem...if not then something else is SERIOUSLY wrong...
Second time it was a bad cap/rotor...
Third time it was the plug wire again...
Fourth time it was the opti going out...
Fifth time it was the plug wire AGAIN....
I just said eff it and replaced the opti, cap, and rotor with MSD opti, MSD cap/rotor, new TPiS Coil Wire, and I used the 8.5mm OTVC SP Wire setup to get them away from the headers...
Since then, no issues at all! So like Built LT1 and Wicked said...start with those culprits and go from there...Should solve the problem...if not then something else is SERIOUSLY wrong...
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ok so the wires are new the plugs are less that 15000 miles on them ant the cap and rotor are less than 2 yeats old and have less than 10000 miles on them.i did the wires whan i did the headers. any more suggestions?
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Iff (if and ONLY if) your Plugs, Wires, and Opti are OK (and I'll bet the issue is simply a routing issue of your plug wires; i.e. - two [or more] too close together, resulting in voltage crossing over to an adjecent wire), then check the ICM and the coil...
BTW - I replaced my 1 YO stock / GM wires with 9 mm units and routed them with wire seperators and (Ta-Da!) my car's High RPM miss went away!
BTW - I replaced my 1 YO stock / GM wires with 9 mm units and routed them with wire seperators and (Ta-Da!) my car's High RPM miss went away!
Last edited by great421; 06-21-2009 at 06:06 PM.
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well i didnt use wire seperators so ill try that next.and the opty isnt new its just the cap and rotor. and i just checked for the wires grounding on the headers and i saw noting.