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Old 08-09-2018, 09:48 PM   #1
strykerhorse
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Member#: 236736
Join Date: Jan 2010
Chapter/Region: MAIC
Vehicle:
2002 WRX Sport Wagon

Subaru Banner Tactrix - logging an 02 WRX that shudders

I'm looking to fix some issues with my 02 wagon and recently purchased a Tactrix 2.0 unit to get the car logged. I'd been experiencing a lot of shuddering and loss of power while at low to mid throttle. I'm guessing it's due to a boost leak, a vacuum leak, or a bad O2 sensor.

I made a log using RomRaider the other day of my drive home and logged parameters recommended by this link.

Link to the log on Google Drive is below:

https://drive.google.com/open?id=12K...AiD4FHZ3Xv6IAA

I'd like some help reading this log to determine if there's a boost/vac leak or if the O2 sensor is bad so I can get my parts replacement budget in order. I appreciate any assistance you all can throw my way!
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Old 08-09-2018, 10:58 PM   #2
2gnt2wrx
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Member#: 123625
Join Date: Aug 2006
Chapter/Region: NESIC
Location: Dover, NH
Vehicle:
2015 WRX
Galaxy Blue

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If it's shuttering and acting up, I'd search around for a broken/cracked/disconnected vacuum hose before logging, follow the black plastic intake tube all the way to the turbo. They are notorious for ripping at the turbo connection, then look at all the boost control solenoid connections, those are notorious for getting brittle and cracking over time. You can spray some carb cleaner over the vacuum system and if the engine changes tone... you found a leak. Any and all leaks after the MAF sensor next to the airbox are going to jack the tune up.
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Old 08-12-2018, 12:11 PM   #3
subaru_gc8
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Join Date: Nov 2002
Chapter/Region: SCIC
Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

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Quote:
Originally Posted by strykerhorse View Post
I'm looking to fix some issues with my 02 wagon and recently purchased a Tactrix 2.0 unit to get the car logged. I'd been experiencing a lot of shuddering and loss of power while at low to mid throttle. I'm guessing it's due to a boost leak, a vacuum leak, or a bad O2 sensor.

I made a log using RomRaider the other day of my drive home and logged parameters recommended by this link.

Link to the log on Google Drive is below:

https://drive.google.com/open?id=12K...AiD4FHZ3Xv6IAA

I'd like some help reading this log to determine if there's a boost/vac leak or if the O2 sensor is bad so I can get my parts replacement budget in order. I appreciate any assistance you all can throw my way!
what makes you think its a leak? honestly it takes a huge leak to make it shudder and it should throw a light as once your fuel trims get to a certain point to compensate for the extra air. My guess would be ignition. When was the last time you changed your coils and plugs? if this hasnt been done, that is where I would start

after looking at your log I dont think your problem is a leak. or af learning stays at zero from what I can tell so its not compensating at all for extra unmetered air so I would start go to what I said
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Old 08-14-2018, 12:38 PM   #4
strykerhorse
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Join Date: Jan 2010
Chapter/Region: MAIC
Vehicle:
2002 WRX Sport Wagon

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Hm, interesting line of thought. What parameters should I be logging to check the coils' function? I changed the plugs (but not the coils) a little after I bought the car around 2.5 years ago.
I do think there's something up with the O2 sensor as it's not changing values over the duration of my drive. I probably had 10 miles on that log---is this a normal thing?

Last edited by strykerhorse; 08-14-2018 at 04:13 PM. Reason: added additional question
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Old 08-14-2018, 09:31 PM   #5
strykerhorse
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Member#: 236736
Join Date: Jan 2010
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2002 WRX Sport Wagon

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Update: I checked if codes were stored and I found a P0031 active for my car. I'll check the resistance of the O2 sensor, and if it's out of spec, a new one may fix all my issues. Here's hoping!
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Old 08-18-2018, 12:32 AM   #6
strykerhorse
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Member#: 236736
Join Date: Jan 2010
Chapter/Region: MAIC
Vehicle:
2002 WRX Sport Wagon

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Update: I replaced the MAF and the shudders went away almost 100%, plus lots of power came out I logged the car and the CL/OL Fueling stayed at 7 (warm-up mode) and never changed. weird.

I'll go for a half-hour drive tomorrow to really get it heated up/verify my O2 is not giving correct info. If that's the case, O2 swap at my house during the week!
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