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Old 10-30-2012, 01:50 AM   #1
BugeyedBandit
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Default Is my motor in danger? (logs included)

I keep getting the P0171 lean code every few days, and I know how dangerous that is to turbocharged cars, so I found a pretty good Subaru mechanic in my area ASAP and had him look the car over.

We found a few odd things, like my O2 sensor wiring. They were connected similarly to this: (these wires were for my evap solenoid and have been fixed already)


My mechanic said that the poor connections and the wires being way too long could be throwing off my O2 sensor's readings enough to cause the lean code. Does that sound feasible? I had a terrible exhaust leak right at the sensor too.

I got the car back today after he fixed the wiring and exhaust leak and it runs a little better, but still idles a little roughly. I hooked my laptop up and it seems that the car is still running lean at idle because the STFT is maxed out at 25%. Once I give it gas however, it comes down:




Edit: here's another log with more info


We checked for vacuum leaks and found none, but I also have a P0457 evap system code, and the car is hard to start after putting gas in. I've replaced the cap already but the code still comes back once every few days. Could this be related to the lean code?

Aside from the rough idle and slight jerkiness under 2,000ish RPM, the car drives great. It has an UP and DP along with a 3" exhaust, but I'm not sure if it's tuned. There's a guy in my area that tunes WRXs, but since I'm not sure if it has a tune already and it seems to have plenty of power, should I just leave it alone? Sorry for all the questions, but I just want to make sure no damage is being done. Thanks for any help!
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Last edited by BugeyedBandit; 10-30-2012 at 01:57 AM. Reason: More info
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Old 10-30-2012, 02:01 AM   #2
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sounds like the evap system has a leak and is throwing it lean

ya have to track that down...this is getting more common as these cars get older

search around here for guys that had the same codes and what they hadda do to fix it
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Old 10-30-2012, 02:09 AM   #3
BugeyedBandit
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^ Thanks for the reply. I did some searching, and most people with the 457 code have the line that runs by the alternator disconnected. That line on my car is blocked off so that can't be it. Do you think an aftermarket gas cap could cause the code? The previous owner put an Autozone special on the car
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Old 10-30-2012, 02:19 AM   #4
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if you have the 2 codes at the same time they are likely related

the gas cap will either seal or not....it isnt voodoo magic on that
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Old 10-30-2012, 02:27 AM   #5
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^ Hmm true. I guess I'll stop by the Subaru dealer tomorrow and see if they can test the cap. What's your opinion on getting a tune? I've read that you pretty much need a tune if you have a DP or UP, and I'm not sure if the previous owner got one
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Old 10-31-2012, 04:29 AM   #6
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I got some better logging software (ECUFlash) and did a 2nd gear pull from about 2,000 RPM and a little cruising in 3rd and 5th. The results calmed me down a little because my AFR is 11.25:1 at WOT and doesn't go lean at all once the car is moving. My boost error and fine learning knock correction look off though from other logs I've seen. Any experienced eyes looking over this would be awesome haha

https://docs.google.com/open?id=0B8X...25hQzFsM0xnc00
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Old 10-31-2012, 04:42 AM   #7
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Quote:
Originally Posted by BugeyedBandit View Post
^ Hmm true. I guess I'll stop by the Subaru dealer tomorrow and see if they can test the cap. What's your opinion on getting a tune? I've read that you pretty much need a tune if you have a DP or UP, and I'm not sure if the previous owner got one
d000000000000d...forget the ****ing gas cap and FIX THE PROBLEM
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Old 10-31-2012, 04:46 AM   #8
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You said in your previous post that the two codes are likely related, so I'm thinking the gas cap is the problem. Or at least part of it
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Old 10-31-2012, 09:23 AM   #9
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Quote:
Originally Posted by Uncle Scotty
sounds like the evap system has a leak and is throwing it lean

ya have to track that down...this is getting more common as these cars get older

search around here for guys that had the same codes and what they hadda do to fix it
Scotty did not mean they were related as in gas cap necessarily but more like a leak somewhere else inthe evap system that would somehow throw it lean. It looks like there are 100s or different reasons for p0457. Yes gas cap is one but there are plenty others too.
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Old 10-31-2012, 09:54 AM   #10
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Quote:
Originally Posted by BugeyedBandit View Post
I got some better logging software (ECUFlash) and did a 2nd gear pull from about 2,000 RPM and a little cruising in 3rd and 5th. The results calmed me down a little because my AFR is 11.25:1 at WOT and doesn't go lean at all once the car is moving. My boost error and fine learning knock correction look off though from other logs I've seen. Any experienced eyes looking over this would be awesome haha

https://docs.google.com/open?id=0B8X...25hQzFsM0xnc00
The factory O2 sensor in the stock location does not read correctly once you get into boost.
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Old 10-31-2012, 12:12 PM   #11
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If I remember correctly, the stock turbo doesn't begin producing meaningful boost until around 3,000 RPM, correct? If so, does that mean the stock O2 sensor readings will be accurate below that? If that's the case, then my AFRs look ok under 3,000 RPM but above idle. I'm just hoping there's some way to tell if I'm doing damage or not based on the logs, so I can stop driving the car until I figure this out.

Last edited by BugeyedBandit; 10-31-2012 at 01:10 PM.
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Old 10-31-2012, 11:10 PM   #12
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In my experience with Mazda vehicles at least (I'm a Mazda tech), an EVAP large leak code and a Lean code set at the same time is pretty much always caused by a stuck open purge solenoid valve. Purge valve stuck open becomes a vacuum leak since its plumbed into the intake manifold. This would also explain the difficulty starting after filling up. The fuel vapors from filling the tank will fill up the intake manifold since the purge valve is open and essentially cause a rich/almost flooding condition. That would be the first thing I would check with those codes and symptoms. I'll bet that is your problem. You can eliminate the purge valve from the intake system and recheck the fuel trims to verify. Gas cap can cause a large EVAP leak code but won't have any effect on fuel trims. This has just been my experience with Mazdas, so YMMV but I have a feeling your problem is along the same lines. Good luck.

Last edited by underdog378; 10-31-2012 at 11:24 PM.
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Old 11-01-2012, 01:30 AM   #13
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Quote:
Originally Posted by underdog378 View Post
In my experience with Mazda vehicles at least (I'm a Mazda tech), an EVAP large leak code and a Lean code set at the same time is pretty much always caused by a stuck open purge solenoid valve. Purge valve stuck open becomes a vacuum leak since its plumbed into the intake manifold. This would also explain the difficulty starting after filling up. The fuel vapors from filling the tank will fill up the intake manifold since the purge valve is open and essentially cause a rich/almost flooding condition. That would be the first thing I would check with those codes and symptoms. I'll bet that is your problem. You can eliminate the purge valve from the intake system and recheck the fuel trims to verify. Gas cap can cause a large EVAP leak code but won't have any effect on fuel trims. This has just been my experience with Mazdas, so YMMV but I have a feeling your problem is along the same lines. Good luck.

which is EXACTLY what the OP woulda found out if...IF he had taken a few minutes to search this issue

and why i posted what i did the way i did....oh well
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Old 11-01-2012, 01:36 AM   #14
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@ underdog378: thanks! I just went out and capped the lines running to the purge solenoid, and the car ran MUCH better and throttle response improved too. The fuel trims are still pegged at 25% though I tried resetting the ECU, and the trims hovered in the single digits for about 30 seconds, then rose to 25% again. Perhaps I have a leak somewhere else then

@ Uncle Scotty: Rest assured I have definitely searched for resolutions to this issue. I'm not one to post questions without doing my homework first.

Last edited by BugeyedBandit; 11-01-2012 at 01:53 AM.
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Old 11-01-2012, 01:48 AM   #15
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Quote:
Originally Posted by Uncle Scotty View Post
which is EXACTLY what the OP woulda found out if...IF he had taken a few minutes to search this issue

and why i posted what i did the way i did....oh well
My bad
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Old 11-02-2012, 10:54 PM   #16
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Well, I found my problem:



My new silicone turbo inlet came in the mail today, so I installed it and the car drove great for 10 minutes. The fuel trims even came down to plus or minus single digits. Then I got on it to make sure everything was ok, and it revved smoothly. The next time I got on it, I hit either a fuel or boost cut at 4,500 - 5,000 RPM. I double checked all the lines I removed during installation, and everything is fine. Does anyone have any idea what could be going on? I did some searching, and people sometimes get this after installing a TBE, but a new turbo inlet wont affect flow enough to cause this I think
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Old 11-02-2012, 11:36 PM   #17
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Maybe its the iPhone but I am not sure exactly what I am seeing in your pic, what is all the white random stuff and which end of the inlet pipe is that?
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Old 11-02-2012, 11:40 PM   #18
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It's the end that connects to the turbo, and all that residue is melted duct tape. The hose must have failed, then the previous owner attempted to just wrap it in tape
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Old 11-03-2012, 12:40 AM   #19
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Seriously man... how has this been over looked? Wtf

It looks like it was on fire or something, yeah that's going to be an issue. Who put the duct tape on it? I hope it wasn't you!
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Old 11-03-2012, 12:44 AM   #20
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It was wrapped in black tape, so it wasn't too conspicuous until I pulled the hose off. Any ideas on why my car is suddenly cutting fuel or boost?

Edit: yeah the previous owner did it unfortunately. I thought it looked funny just from looking at it through the intake manifold, so I ordered a silicone inlet hose and found this when I took it off today
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Old 11-03-2012, 07:42 AM   #21
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Quote:
Originally Posted by BugeyedBandit
Well, I found my problem:

My new silicone turbo inlet came in the mail today, so I installed it and the car drove great for 10 minutes. The fuel trims even came down to plus or minus single digits. Then I got on it to make sure everything was ok, and it revved smoothly. The next time I got on it, I hit either a fuel or boost cut at 4,500 - 5,000 RPM. I double checked all the lines I removed during installation, and everything is fine. Does anyone have any idea what could be going on? I did some searching, and people sometimes get this after installing a TBE, but a new turbo inlet wont affect flow enough to cause this I think
Did you try resetting the ecu after replacing it and see if it makes any difference? Maybe the ecu learned funny stuff while this was in there
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Old 11-03-2012, 12:01 PM   #22
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Quote:
Originally Posted by BugeyedBandit
It was wrapped in black tape, so it wasn't too conspicuous until I pulled the hose off. Any ideas on why my car is suddenly cutting fuel or boost?

Edit: yeah the previous owner did it unfortunately. I thought it looked funny just from looking at it through the intake manifold, so I ordered a silicone inlet hose and found this when I took it off today
Ok, makes a little more sense. You should re-set your ecu and run a boost leak test. Any leaks will cause issues, in your case... this leak is an extreme example of someone completely not having a clue.
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Old 11-03-2012, 12:37 PM   #23
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I reset my ECU the day before yesterday, but I'll try resetting it again. Time to look up how to do a boost leak test then haha
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Old 11-03-2012, 04:20 PM   #24
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Just reset my ECU and did some driving, and it's cutting fuel even harder than before! I looked around under the hood, and the BPV fitting in the new inlet hose looks like it may have shifted slightly. I don't think that enough to cause such a hard fuel cut, especially since my AFRs are actually on the rich side right before it cuts fuel. I'll put a better clamp on it and see if that helps
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Old 11-04-2012, 04:41 PM   #25
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For anyone following, I fixed the fuel cut issue with 2 of the biggest hose clamps that would fit on the BPV line. Apparently the ones that came with the kit weren't strong enough. Pulls hard to redline now


Even after removing the purge valve solenoid and capping the lines like underdog378 suggested, it still struggles to start after putting any amount of gas in the tank though. One day at a time I suppose
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