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Old 04-12-2014, 06:26 PM   #1
Scooby Newbie
Member#: 236724
Join Date: Jan 2010
Default EJ25 Electrical Issue? NEED HELP ASAP!!!


I have a '02 WRX that I build a EJ257 (forester turbo) with EJ20 heads. The car is at the tuners and we can not figure out what the problem is. This is what the tuner sent me in an email.

Car starts , idles , runs and drives and yet we are still trouble shooting a electrical intermittent misfire short of some sort . Tachometer starts to bounce and or drop upon cruising or full throttle , this occurs and or starts to fluctuate around and between the 5000-5500 rpm .

I have a BC272 cams and oversize 1mm exhaust/intake valves. Stock ECU with Cobb Accessport. I've been struggling with getting this build together for a long time now. Any help would be great. List of mods:

2003 WRX transmission
VF39 turbo
Manely Pistons
BC 272 cams w/ BC oversize valves
STi fuel injectors
Perrin Fuel Rails
Walbro Fuel Pump
Perrin Intake
Stainless Steel Turbo Inlet
Cobb Accessport
Turbo XS FMIC w/blow off
ACT Streetlight fly wheel
Bully Clutch

What do you guy think it could be?
Short/Bad wire?
ECU Problem?
Is there a compatibility issue with the mods?

We swapped out all sensor (crank, cam, maf)
New plugs
New Coils
New Injectors

Thanks for any HELP!!!!
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Last edited by themisiek1; 04-12-2014 at 06:37 PM.
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Old 04-13-2014, 03:25 PM   #2
Scooby Guru
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va

Has your tuner tried datalogging the car? It's going to be impossible to tell what is wrong with it unless you can provide some data. Compression/leakdown test? Fuel pressure checked?
quazimoto is offline   Reply With Quote
Old 04-14-2014, 11:56 AM   #3
Scooby Newbie
Member#: 236724
Join Date: Jan 2010

Fuel pressure was checked.
ECU was swapped
Engine harness swapped

Compression/leakdown not done. I will see if the car was datalogged today.
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Old 04-14-2014, 06:13 PM   #4
Scooby Newbie
Member#: 355139
Join Date: May 2013
Chapter/Region: SWIC
Location: Albuquerque, NM
2003 WRX wagon VF28


Kinda sounds like a grounding problem. Make sure everything that needs to be grounded is tightened down.
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Old 04-14-2014, 09:38 PM   #5
Scooby Specialist
Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
2001 Forester
STi II type M


It could be a painstaking process, but you will need to check each and every ground, as well as check each connector for loose connections, corrsoion, cracks, seal breaks, ect. If that gets you nowhere, then its loop and resistance checks.
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