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Old 04-09-2013, 01:19 AM   #1
Scooby Newbie
Member#: 351420
Join Date: Mar 2013
Chapter/Region: NESIC
Location: Syracuse, NY
2002 WRX

Angry All four cylinders misfire at once...

So ive seen this thread numerous times in the last week or two, and ive read every bit of them! But most seem to be years old or not on par perfectly with my problem. I just wanted to keep a log of my progress/ braintrust on ideas of what i should try.

So I have owned this 2002 WRX for a month now. All has been ok, it does need some stuff (clutch, engine cradle, going to do TBelt and HGs to say I did). About 2 weeks after owning, I threw a CEL. Pulled them with my scanner and found P0301, 302, 303, and 304. No random cylinder misfires, no lean or rich condition. I did not recollect what gear i was in, or the speed or RPMs. Car ran fine, no roughness. Cleared the codes, everything was bueno. Fast forward four days, I get a blinking CEL on the highway, 5th gear, accelerating from 70 to about 80. It did not stay on however. No roughness. Another few days later, I throw a solid CEL. Pulled whatever freeze frame data my barebones MAC scanner could. 50% load, 43 mph, STFT 0, LTFT 0, Fuel System Open. Today I threw it again. Data says 47% load, 81 mph, STFT 4, LTFT 3, Fuel System closed. I was in 5th gear, passing (which now sounds like a bad idea). Now to end this story of misfires, I was driving home just an hour ago, pulling through 4th gear at which i assume was 50% to 75% throttle (I rarely go WOT for fear of fuel cut). My CEL blinked about 10 times, then went out.

From what I have gathered from past threads and my own knowledge, I have narrowed it down to a few things I think could be F'ing my baby up.
I do not think it is coils, that would not throw all four cylinder codes at one time. I dont think it is a slipped timing belt. If the belt slipped on one cam gear, that would only cause two cylinders to misfire. I think it may be a Lightweight Crank Pulley "phantom misfire" problem. The previous owner has done some questionable mods to this car; Vishnu Stage Zero tune, 3in turboback, LIGHTWEIGHT CRANK PULLEY, and a MBC. So Id like to hear if any of you have had these "phantom misfires". I was thinking it could be plugs as well. Not fouled, but maybe not gapped correctly. My last theory, and this may be way out in left feild, but overboosting. Im not sure what the boost level on the MBC is set to because i have yet to fix the past owners semi-functional KPa gauge, but i bet he has it set up to 15 or so. I read somewhere that the factory boost controller sets 5th gear to 8psi or so. So in theory, when im on boost in 5th, i can produce up to 15psi, almost double the factory level.

I'm going to start checking sensors tomorrow (Cam, Crank, MAF, etc), and i have already checked my inlet underneath the hose clamp. For now Im going to drink beer, and forget what a CEL even is. But any input will be put to use first thing in the morning!
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Old 04-09-2013, 08:20 AM   #2
Scooby Guru
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va

Generally the "phantom misfires" don't cause the gross misfire (blinking CEL). You just get the DTC. I just retuned the ROM in the ECU and enabled Romraider's misfire fix. The bugeyes have always been over sensitive to misfires.
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Old 04-09-2013, 08:52 AM   #3
Uncle Scotty
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Join Date: Mar 2002
OK buy Nates beans


if you have a bit of a boost leak and bad plugs it may misfire when it gets too rich
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