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Old 08-10-2013, 09:43 AM   #1
mikeydrives1
Scooby Specialist
 
Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default Mysterious breakup/misfire and loss of connection during datalog.

Welp, today i come to you guys, NASIOC, for help diving into a very troublesome and frustrating issue that is plaguing my swapped 01 forester, ever since i had the longblock replaced.

Okay, so a little background here. I have a 2001 Forester (L) with a Full 2004 STi swap in it. The swap and wiring were done properly and proffesionally by a shop, and the car ran Great from january of 2012 to January of 2013, when it met with an unfortunate end of a blown motor. The vehicle sat from january until June when i finally was able to have the longblock replaced with a Brand new one from the dealer. Upon first startup, it gave me some hesitation and misfire issues. After doing some troubleshooting, it turned out to be bad coilpacks in cyl 2 and 4. Replaced all 4, new plugs and i was out the door, starting the 1000-mile new engine break-in procedure.
Heres the engine setup:

-2004 STI (new) EJ257 longblock
-DW 740cc Injectors and walbro fuel pump
-Brian crower Valves and Springs
-Manley pistons (standard 99.5, but 9:1 comp/ratio)
-Standard Intake, Downpipe, Catback exhaust (Cobb)
-Gates timing belt kit
-FP 68HTA turbocharger (8cm hotside)
-Grimmspeed 38mm Tial Wastegate (kit) with uppipe
-Grimmspeed EBCS


So now, we are facing a few small issues, one with the Cobb Accessport, and im trying to figure out if these are all connected, or some kind of electrical issue that is haunting my system.


So, on the dyno we started with 3rd gear pulls to get the feel of things and see how the new tune was feeling. Oddly enough, when under WOT throttle, the car began to sputter / hesitate / misfire as boost would build up to the mid teens (14.7 psi spring) , throwing general PFFFF and PFFFE misfire codes, as well as 3rd cyl misfire, and would not want to rev out any more. We also noticed that during this time, as you went WOT to log with Accesstuner , it would disconnect during the higher loads, and then re-establish a connection when the throttle was lifted.

We never ended up seeing past about 4500rpm on any of our pulls, for fear of something being harmed and deciding to seek higher authorities on the matter. However, when under light throttle, or with the internal gate popped open to prevent boost passing about a couple pounds, the engine will rev out like an angel to redline, without so much as a hiccup. Only when it starts to build higher amounts and full throttle is engaged, does it start to sputter, misfire and hesitate, accompanied with loud backfires out of the wastegate and a blinking CEL, and a loss of datalogging. We thought it might be the tune, but my friend and shop owner is a very knowledgable pro-tuner, and from what i can see, my DAM and learning views are giving us feedback that the car is doing OK with where we are now ( 1.0 and all within +/- 7% ), only pushing conservative amounts of timing and boost, to get a feel for the new setup. I am confident in saying that we spent more than enough time troubleshooting with the tune(s) that they can be rule out as not being the case

Over the next couple weeks, we ran a multitude of tests to see if something was causing this terrible misfire. Here is a breif list of what we have done so far ......

- Leakdown, compression and timing tests : Reults were all excellent and on par.
- Voltage drop on the DW injectors: Consistent on all 4
- Attempted dyno Run's on 2 different (04 STI) ECU's .... same issue every time
- Changed tune to speed density: No luck there.
- Attempted different approaches with the tuning: Didnt help
- Replaced all 4 sparkplugs and coilpacks. Plugs gapped to OEM specification: Stopped initial misfire from rebuild's first startup, but has not solved the issue at hand.
- Swapped MAFS; No change


The Car's previous motor had a very similiar setup, minus the high comp pistons and EWG kit, and the car was very happy with the tune. It never let me down, and drove very smoothly, making 315hp and 330 torque on a somewhat conservative approach.

Also i should note, the level of misfire is inconsistent and random. Some days, i can get up to maybe 10 or so pounds of pressure at very light throttle, and it wont hiccup until i floor it, and other days, driving around it feels like its not firing correctly, and breaks up the moment it sees over 4 or 5 lbs of pressure.



Okay, so here is what i am thinking .....



Couple of thoughts / conclusions....

1.) We ruled out any type of mechanical issue within the block or heads. Replaced the ignition componenets and found no obvious signs of defect with the harness (04 sti harness properly merged to 01 forester harness, and drive-by-wire)


2.) The main fuse (SBF no. 1) was blown when we removed the motor 8 months ago. Our fault, we mistakenly grounded the starter motor wire, while things were still connected. I replaced this with a Generic Baussman brand (autozone) 80 amp fusible link. I have a hunch this may be allowing too much voltage across the car's system, which would explain electrical phantom issues of being kicked out of datalogging and misfires at WOT loads. I am logging 13.5 to 14+ volts with the AP's readout at idle of 1000 rpm during general operation, whereas with my old setup, it was always in the 12s/13s. Done some research but cant find definitive answers as to whether or not a voltage spike can cause all components to go screwy when WOT is applied.




3.) Perhaps a bad ground somewhere. We double and triple inspected the harness, from what we can see, and see no obvious signs of deterioration. I even have a supergrounding Kit from Paranoid fabrications (Via RS25 forums) which i have re-arranged every possible way i can think of, with no change in results. i know the car sat for 5 months before being touched again, but the harness and re-used motor components were sealed in containers and placed in the trunk of the car to keep them out of the elements. Where would i even begin to look, to find a bad ground? The engine grounds look sound and dandy, no signs of rust or corrosion, anywhere.




So, i am placing a call for help out to the well-learned individuals here. I will be open and grateful to any advice that comes my way at this point.


-Mikey



EDIT: CLIFFNOTES
-Replaced longblock after old one went
-Car has bad misfiring and hesitation when under load, losses AP datalog connection when this happens
-Ran lots of tests and cant find cause.
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Last edited by mikeydrives1; 08-10-2013 at 10:45 AM.
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Old 08-10-2013, 11:34 AM   #2
fastblueufo
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Member#: 212154
Join Date: May 2009
Chapter/Region: South East
Location: Ed@fastperformancetuning.com
Vehicle:
02 billet crank
pauter rods, pt5857, E85

Default

A battery fixing to go bad will cause logging to stop and also a alternator that isnt up to par.
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Old 08-10-2013, 12:35 PM   #3
mikeydrives1
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Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

Quote:
Originally Posted by fastblueufo View Post
A battery fixing to go bad will cause logging to stop and also a alternator that isnt up to par.
Its a brand new Battery in there, as of April, and the alternator is the original forester one with 140k on it.

Can something that regulates voltage be going bad in the alternator?
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Old 08-14-2013, 08:24 PM   #4
mikeydrives1
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Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

bump!
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Old 08-16-2013, 12:11 PM   #5
mikeydrives1
Scooby Specialist
 
Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

Bump!
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Old 08-16-2013, 09:49 PM   #6
mikeydrives1
Scooby Specialist
 
Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

I made a video to demonstrate whats going on. Might make it easier than just reading this whoel thread.

http://www.youtube.com/watch?v=iWAgx...ature=youtu.be
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Old 09-03-2013, 06:57 PM   #7
mikeydrives1
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Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

Just replaced the injectors (dw740s) with brand new ones and no change in the issue of the cyl 3 misfire at idle and then again under load.
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Old 09-03-2013, 07:27 PM   #8
RaceFaceXC
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Location: stupid Florida
Vehicle:
2007 No YELLING
on the bus!

Default

under load the engine twists on the mounts, and all the wiring harness' and connectors move with it. have you checked all of the connections closely and all of the wiring for damage.
if you log with another method besides AP, does it also have the same issues?
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Old 09-19-2013, 05:30 PM   #9
mikeydrives1
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Member#: 262117
Join Date: Oct 2010
Chapter/Region: Tri-State
Vehicle:
2001 Forester
STi II type M

Default

All the connections seem to be in proper order. Where could one find an 04 Sti wiring diagram online?
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