Hi guys, I have been having a problem with my 2003 Evo 8. It started with just a small amount of skipping, mainly at full boost, in the lower three gears. It also resulted in a SES light, which i pulled the famous P0300: random misfire code from. So, i replaced the plugs and checked the wires and coils today hoping to cure my misfire/fuel cut/ who the hell knows... I also installed a greddy profec b to monitor my boost more accurately. Ok, so the new plugs are gapped and installed and off we go. First ride was awesome, just a small amount of skipping, but much better than before. Now for the bad news.. I went out to eat later and the car was running relatively smooth all the way to town. Keep in mind, i did run WOT in third gear just to see if it would start to mess up again. It did not. Upon leaving the restaurant, i ran WOT from 2nd to 4th while getting on the freeway. Then it happens, 4th gear at around 35/3700 RPMs, it started skipping violently at approximately 17/18.5 psi of boost. This has continued for the whole 20 mile trip home in any gear. As soon as the boost hits around 17/18 psi, the car starts loosing power and skipping like a governed car would when you hit the governor. I have no idea what is going on, and i would greatly appreciate if any of you would be able to help me or point me in the right direction. Thanks ahead of time for all who read this and give me a shot to try to help.

Dave

 

Bump!

 

...by skipping, I'll assume you mean that its breaking up aka misfire. What are your plugs gapped at?

 

Yeah, what does "skipping" mean? That's not a term I've seen used before in such a case.

If you mean misfiring/sputtering, then it's spark related. Tell us exactly which plugs you used and how you gapped them. Once we're sure those are correct, then we'll help troubleshoot the rest, such as checking the coil packs.

 

Yes, by "skipping" i mean misfiring and sputtering. The plugs i installed were the factory replacement NGK irridium plugs. I gapped them at .032.

 

...okay so gap them to .25 and check back with us.

 

Will do, I am at work right now, but i will regap them as soon as i get home. Thanks for the help guys, i really appreciate it.

 

UPDATE: I have regapped the plugs, and i also found that the insulation around the electrode was chipped pretty badly on one of the plugs. With that said, i have made about six 1st through 3rd pulls with no misfire. I will know more tomorrow when i get to open it up in the higher gears on the way to work. Hopefully the problem is solved. I GREATLY appreciate you guys taking the time to hep me out with this. I will post back up with details on how the car does in the higher gears tomorrow morning sometime.

 

Alright, i am at work, and i managed to get a full 4th gear pull on the way to work this morning. No misfire and the SES light has not came back on. Thanks for all the help and advice guys.

 

If the insulation is chipped, you should really replace the plugs. If you dont want to spend the money on the expensive iridium, buy the NGK copper replacements. BPR7ES

 

yea evo 8 plug gaps should be done at 25 and below specialy on stock ignition. A plug gapped to much can cause a fatal misfire.

 

Yep, that's why I asked what the gap was...misgapped.

 

^ we sir are on the same page hahaha

 

I did buy new plugs. I found the NGK irridiums at NAPA for $14 each. It was alot better than the $23 at the other parts stores. I also went back and bought another to replace the one that was chipped. Thanks for all the help guys. I definitley know who to ask the next time i have misfire issues.

Dave

 

Ok, so the illusive random misfire has struck again... It now happens after i have been driving for a while (more than an hour) and occurs more often after spirited driving rather than all of the time during normal driving. Here is the kicker, when the misfire happens, you can let off the throttle and it will stop. It will continue this for a few miles, and eventually stop altogether. Any advice?