P300 Random Misfire

[TjXiong]

Car: 1997 Eclipse GST Spyder

I recently been having a cel (reads p300) random misfire and everytime when I go WOT the car will misfire and studder. I first bought new wires and the car no longer misfire; a week or so after the car acts up again. Now I replaced the plugs with ngk iridum gapped at .28 with the new plugs and everything runs great but the cel keeps on coming back and forth --what could be the problem? I ve been searching and been reading all these possible problem; im stuck.

MODS - B16g - 550cc -- evo 3 o2 housing -- custom exhaust -- safc --injen intake -- blitz bov -- hallman mbc -- boost gauge -- air/fuel --walbro 255 -- this all i can remember but will update this as when i get home.

Thanks.

[scheides]

I had this problem on my 97 but never really figured it out. Similar setup. Do you have a 6-bolt swap? I did.

I think dsmlink would fix it, but not sure. That is what I was going to try, but ended up selling the car first.

[TjXiong]

Im still running a 7bolt. Ill look over everything again and do the basic and work my way around. I hate this stupid cell; DSMLINK will be my next step.

[awd-drifter]

is your bov recirculated? does this only happen when you're in boost? when it the cel comes on and off, when does it usually happen? I know that sometimes my cel would come on at times and go off when I'm cruising, which I speculate could be a faulty tps.

Just googling the the code, it seemed like it's an ignition issue. might be the coil pack.

[Pushit2.0]

I would guess you ment a P0300 code? If so here is the Diagnostic Trouble Code Tests and Associated Procedures for that code: http://www.dsmstyle.com/photopost/data/649/78767538.JPG

Or:
http://www.dsmstyle.com/photopost/data/649/78767538.JPG

[TjXiong]

Read the cel again and one of the code came back as a faulty/clogged catalytic converter; now I have been reading and this may be a cause to the p0300. I remmember having the faulty/clogged catalytic converter before the random misfire p0300. Should I replace it?

[Spikesoftail]

Generaly a p0300 wont be caused by a plugged cat, its usually ignition or fuel related. Although it can be timing. An engine missfire can definatly will definatly plug your cat though. Cats are very delicate and anything causing your engine to run poorly can and will plug your cat. Unfortunatly a 97's computer is very primative as far as engine data is concerned. They are even harder to diagnose once you start modding them.

[TjXiong]

The cel is on but I havent feeel any hesitation or misfire while in driving mode even when going WOT reaching 18psi. Ill check the car when I get home and see whats going on. No idle problem even on cold start (500-600 rpm)

[scheides]

Interesting it says -10°C and higher, its probably colder than that here lately. Not sure what that means, but I think mine did it more often when it was cold.

[1QUICK4]

1st things 1st get rid of those iridium plugs. I had the same issues with those plugs.

Run the correct NGK coppers that Mitsu recomends