Got these codes today (random misfire, cyl 1, 3 misfire). Car seems to drive OK. Car is Cobb Stage 2, STI up, TBE. No other engine mods. 94K miles. Maybe related or not I suspect to have a minor boost leak keeping me at about 14.5 psi (Cobb peak is 15.5 or so). I also got gas today at Chevron (station I had used before). Little bit I saw in a quick search here and NASIOC was check plugs, coil packs. Any other advice? Any significance of the #1 and #3 cylinder? No work has been done recently. I did wash the car today(not the engine though). Appreciate any advice.
bad gas. Clear and drive. If they come back after getting a different fuel then you have some type of mechanical issue.
Mechanical issue? I cleared and have driven once and they did not come back. Unfortunately it will take me a week to get rid of the gas. I forgot to mention - I did change the plugs at 60K. I have 94K now.
Mechanical as in a coil pack, plug, MAF, MAP, A/F sensor, cam or crank sensor, injector, low fuel pressure or high fuel pressure, some sort of leak, valve clearance...something. Let let me know if it comes back and under what *EXACT* conditions. Thats because you have a 2004~2006 EJ255/EJ257 engine with the factory yellow 550cc sidefeed injectors. 50% or more of all of those will develop missfire/rough idle issues. Thus far I've only personally seen TWO top feed injectors fail. One of them wasnt even a SUBARU built injector, it was a power enterprise injector...in an 03 WRX. The other one was a bone stock 2000 Outback, EJ25 N/A.
34k on spark plugs and I bet the gaps are HUGE! Iridium, platinum, it makes no difference. We have now had two people that had high end spark plugs at 30k or over and when they pulled them the gaps were monsterous (36-42). That could also lead to it.
^Yes it could...but only under high loads like WOT or similar. Typically plugs with that gap will be "ok" during warm up and normal driving on a stock-ish car. Note the "ok" part...
Thanks for all the feedback guys! I have driven 2 times since the reset and hasn't come back. If it does, plugs will be the first thing that gets changed.
When is it popping up? Also be sure to get that boost leak fixed, that could also cause it...combination of tune going rich in open loop and old plugs.
This has not come up again. Based on other recommendations, I will plan to change the plugs soon. Thanks for the help.