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Misfire on 2&4

98DaytonaGTP

98DaytonaGTP

New member
I don't mean to double post something on a misfire just seems like a different problem. So my 98 gtp is misfiring on 2 & 4, now I have replaced the plug wires spark plugs, Icm, swapped the coils packs, even moved # 2&4 injectors to 1 & 3 to see if it was causing the misfire but it still keeps showing up at 2 & 4.... Any ideas?
 


Since it's two different coils, that is very odd. It's much easier (been there..done that) to swap up the wires in error since you can't get great visibility back there.
 


Is your GTP completely stock? As in, not dropped a pulley size? Do you always run premium fuel?

Not sure if you've read the "safely modding your 3800" thread, but maybe this will help.

4) Spark Plugs - Change out those stock spark plugs with new ones to restore any lost power. Brands that most tend to go with are either Copper Core Autolites or NGK's. They range as follows in order from hottest to coldest plugs...remember...you want the hottest spark you can get away with...so running a super cold plug on a larger pulley to combat knock isn't the best plan...OEM replacement ACDelco's, AL606's, and AL605's are basically for stock cars or very small bolt-ons still running the stock S/C Pulley or modded N/A guys...you want to keep a hot spark. NGKTR55/AL104's for your 3.4" Setup, TR6's are a tad cooler...best used around the 3.25" pulley area, and AL103's...are for the extreme supercharged application...3.0" pulley or lower. Here is a picture to reference the firing order and the correct coil number if yours aren't numbered or you just need a quick reference picture:[URL]http://i33.photobucket.com/albums/d6.../plugwires.jpg[/URL]

AC Delco Factory Replacements: Stock
Autolite 606: Stock
Autolite 605: 1 Heat Range Cooler
NGK TR55: 1 Heat Range Cooler
Autolite 104: 2 Heat Ranges Cooler
NGK TR6: 2 Heat Ranges Cooler
Autolite 103: 3 Heat Ranges Cooler
 


How are you reading the misfires? Scan Gauge, DTC codes.

Misfire at idle (vacuum)
Misfire under boost (pressure)
 
P0300 is a code for random misfire. Not sure how you would deduce that its 2 and 4. How did your coil packs fit on the ICM? Do they pull off and on real easily?

I had random misfires. Went ahead and replaced the stock coil packs on my 133k mile car. New ones took a good amount of force to push on the ICM prongs. Very tight fit. Old ones I could just drop on. So far it was the best mod I've done to my car! Under 70 for all 3 coil packs. If you have high mileage I'd recommend just replacing them as a maintenance thing anyways.

Only replace with OE ac delco cp's.

Edit: I may have misread your reply. I see now you probably meant a 300 code for misfire on 2 and 4. Gotcha. ;)
 
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