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Old 05-10-2015, 11:22 PM   #1
Karbine
Scooby Newbie
 
Member#: 368789
Join Date: Sep 2013
Chapter/Region: South East
Location: Apopka, FL
Vehicle:
2002 Impreza OBS
Aluminium

Default 02 WRX - Hesitation/sputtering

Hey all, having a big issue here. I'll detail it as simply as i can.

Car: 2002 WRX Wagon, 166k

Mods:
HKS short ram (currently reverted to stock airbox/k&n
Modified(?) Stock injectors
Turboback exhaust
TD05 16G
Stage 2 tune
Mishi radiator/lines
HKS SSQV
Stock BCS but it was tuned for an MBC; truboost gauge was stolen when I got the car.

The problem:
Car is jerky in low revs, and between 4-6k, in and out of boost (usually in) car sputters and sometimes bucks, power loss, smell of fuel. Sometimes my throttle just does nothing. When it sputters/bucks, it's like I've let off the throttle suddenly. There is no CEL, car does not have issues idling and does not stall. When I start the car it will run rich and very rough for about 30 seconds and smooth out. The problem would used to be resolved by restarting the car, now only ecu reset will "fix" the problem for about 200 miles. The hotter it is outside (85+, florida) the worse my sputtering and bucking gets. When it's nighttime, next to no problems.

I have had this problem for weeks (and it's getting worse) and only now have I gotten a cyl 1 misfire code (of which this code will not show up to average scantools. it took a $6000 scanner to pull it.) I have an intermittent front o2 sensor failure CEL but it comes and goes every few months and performance was never affected; previous owner said this is because of the tune (done by Jestr) Vac at idle is 17 hg.

What I've done:
Replaced plugs, compression is 150 on all cylinders.
Cleaned MAF
New fuel filter
New air filter/changed to stock airbox
Cleaned TPS connector. I'm sure the TPS is being the culprit in all this but I have no way to test it. On the scantool the throttle reported as .5V at idle. Maf was at 5
Soapy water boost leak testing. Found a BOV gasket leak, fixed it, no change in problems. Going to have the car smoke tested tomorrow.

I don't have an AP or a tactrix, unfortunately.

My HKS uppipe has a very tiny leak at the weld, I only found it by seafoaming the car and looking for exhaust leaks. Smoke did not come out, but I could see boiling water there.

Any ideas? I have been scouring the internet for solutions.
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Last edited by Karbine; 05-11-2015 at 12:18 AM.
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Old 05-11-2015, 03:17 AM   #2
ImprezaLover94
Scooby Newbie
 
Member#: 265684
Join Date: Dec 2010
Chapter/Region: MAIC
Vehicle:
2002 WRX Wagon

Default

Well I'm not sure if they are causing your problems but I see 2 problems:

You say the car was tuned for a MBC but you have the stock BCS on there. That could potentially be a problem if the boost control is not working the way it was tuned for.

You say Modified(?) Stock Injectors. Are they modified? By whom? Were they ever flow tested? Did you try running some Royal Purple fuel system cleaner through it?
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Old 05-14-2015, 12:59 AM   #3
Karbine
Scooby Newbie
 
Member#: 368789
Join Date: Sep 2013
Chapter/Region: South East
Location: Apopka, FL
Vehicle:
2002 Impreza OBS
Aluminium

Default

An update:

Found a large boost leak in Y pipe, fixed it. Reset ecu, problem went away again for 150 miles. Still sputters when i go beyond 8lbs of boost. I can't datalog the system, something is blocking obd2 things from reading it, so I am going to the original tuner of the car to try to monitor everything. There is no leak in my uppipe, it was just AC runoff.

Car has been running on stock BCS for almost a year without issue. I also found out my TD05's wastegate pressure is like 15+ lbs for some reason. Previous owner was preparing it for an EWG. how the hell is the stock bcs choking boost to 10-12 with a wastegate setting like that? I ran the car with the BCS bypassed and I had crazy good spool speed but I would hit 15+ lbs of boost. Turbo is 5 years old/~60-70k on it.
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Old 05-14-2015, 12:50 PM   #4
Karbine
Scooby Newbie
 
Member#: 368789
Join Date: Sep 2013
Chapter/Region: South East
Location: Apopka, FL
Vehicle:
2002 Impreza OBS
Aluminium

Default

Fuel pump (walbro) is also 5 years old. Gonna replace that thing.
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