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04 STI Misfire ONLY on HOT START

1098 Views 0 Replies 1 Participant Last post by  scoooby_newbie
Hi guys

i am currently am having an issue on my 04 STI EJ257 on a idle at a operating temperature only. The problem started about 3 months ago and i have and several mechanics telling me they dont know what the issue is could be or where to even look after there equipment is telling them that my car is completely healthy:tdown:

Tests Completed as followed:

-Compression Test
-LeakDown Test
-Fuel Pressure Test
-Timing is dead on
-Swapped Coil Packs
-Injectors
-Brand New Oem Iridum Plugs - Gapped Correctly

Mods List :

3" Dowpipe - Catless
3" Custom Exhaust from downpipe
Cobb SF Intake
Cobb Stage 2 93 Octane - (Tried Changing maps around thought maybe it was a bad tune at first,condition exists even on stock map)
Mishimuto Radiator


So the Problem started im not quite exactly sure when but it goes like this, Cold Start no problems idles great no misfires detected , as long as the temp stays under the line where it sits on the temperature gauge on the dash , once car has acheived operating temps, the car will misfire as soon as the car is started and everytime as long as the temp doesnt drop below that point, but once under that threshold misfires dissapear :confused:

My acessport will log on Cylender #1 up too 28 misfires, and Cylender #3 usually no more than 10-12. this condition lasts with a shaky rough sometimes knocky idle and can last upwards to 30 seconds. i am seriously stumped, everything is rock solid from what i can see, my boost is controlled perfectly with no vaccums leaks .

ANY POSITIVE HELP THAT RESULTS IN A FIX OF MY STI I WILL REWARD YOU WITH A STEAK DINNER !!! :):tup:


If anyone has experienced or has heard of anything that could potentially cause an issue close to this please speak up
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