Thread: Higher Rpm missfire...possbile culprits???

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  1. #1 Higher Rpm missfire...possbile culprits??? 
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    Ok i have a 2001 GTP and it runs fine cold. It has a noticeable miss between about 4-6k. It seems intermittent and not at all like one cylinder. I was reading other forums and they said it could be iridium plugs? i know i bout delco iridium plugs because the guy at autozone told me that ethanol doesn't burn right with copper plugs.... blah blah bunch of **** i know but i thought it couldn't possibly hurt?? I am running a mild cam, with no cat, ported blower with a 3.4 pulley.. I have a PT scanner and noticed the O2 sensor was reading lean (840-890) at WOT and i was getting about 6 degrees of knock which is kinda making me think it isnt the plugs but maybe the fuel pump?? I just replaced the ICM (because i had a steady miss on cylinder 6) and the fuel filter to make sure it wasnt somthing stupid like that. the car has about 175k so any other suggestions??? Oh and i also replaced the throttle body with a 1998 (and recalibrated the MAF tables with a 1998's) because i had one laying around and didnt want to buy a new one :/. Any other suggestions for this guy would be awesome!!
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  2. #2 Re: Higher Rpm missfire...possbile culprits??? 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    IF you have the mods to run that cam, I would suggest you use the right plugs, and from the sound of it, you need autolite 104's copper cores.

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  3. #3 Re: Higher Rpm missfire...possbile culprits??? 
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    Ya it only really starts doing it when i hit higher rpms and its warm.. Ill head out to my buddys shop tomorrow and hook a fuel pressure gauge up and check that out, and i can def switch the plugs out with some 104's if u think that would help? But why the lean reading on the O2's?

    When its cold the 02 readings are in the ball park of 935-950....
    Last edited by mr_gtp; 04-09-2012 at 09:56 PM. Reason: more info
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  4. #4 Re: Higher Rpm missfire...possbile culprits??? 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
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    YOu need a Wideband o2 sensor to really know what AFR you are running, going by o2 mv is kinda just guessing.

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