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Higher Rpm missfire...possbile culprits???

M

mr_gtp

New member
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!!
 


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....
 
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