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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '05 AWD Pontiac Vibe
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Discussion Starter #1
2010 OB 3.6R 170k Miles

For the past couple months I have always felt my OB misfiring slightly between 1750 and 2200 rpm when going up a steady low hill (slight increase in engine load). I recently very occasionally have a flashing CEL that only lasts 4 seconds then goes away and every so often I will have the codes stored under pending faults. The codes are: P0302, P0304 and P0306. I have all new oem spark plugs, new coilpacks (expensive Intermotor brand made in Poland), a new group 34 battery that tests well within limits and new ground cables attached to the heads plus an extra going to the alternator bracket from the battery. I thought I felt this misfiring start around 8 months ago but it never thrw a CEL or even a pending code so it seems to be very slowly getting worse. This makes me also think it is more likely a failing solenoid.

I will hopefully have SSM up and running soon so I can properly view what the VVT solenoids are doing but tonight while driving I was able to obtain some minor info with my decent scanner (it reads virtually everything for most manufacturers except Subaru unfortunately). I was able to find VVT solenoid system check for bank 1 and 2. I don't know how useful this value is but it essentially gives you a value in degrees and as long as it is below a set value then it marks it as "pass". The odd thing is the upper limit value is somewhere around 15,000 degrees so I don't think it is very useful as I can't see it ever really showing a fail. What stood out to me is that Bank one would give a reading around 150-320 degrees but bank 2 ( the problem side) would always be around 400-600 degrees greater than bank 1. the value seems to be up dated every 5 mins of driving but no matter what they were, bank 2 was always much much higher and bank 1 never exceeded 360 degrees.

Is anyone familiar with this type of "system checks" and should these value be very close in number? This obviously doesn't point to if the failure is with the intake or exhaust solenoid however it shows a large difference between bank one and two.

I was also able to access "cylinder 1 timing advance" (there is no other timing advance PID available) what I noticed is this always sat at 15 degrees when at idle and would be around 34 degrees at steady driving. I have read in the past that this value should read 0 degrees when at idle. Is this true? This also doesn't pinpoint me to any specific solenoid but it may shed light on the vvt system being faulty.

I read on the LegacyGT forum someone who had the same issue with his Legacy 3,6R and he never had a specific solenoid code pop up (P0014 IIRC) until he hooked the car up to SSM and all of a sudden noticed the code. A new exhaust solenoid fixed the issue.

I don't want to replace both the intake and exhaust solenoids if only one are bad and I'm never one to just load the parts cannon so anyone knowledgeable or experienced with this it would be appreciated to hear your input.
 

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Outback 2011 3.6R Premium
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The only thing I can comment on is that the cylinder one timing advance should NOT be at zero (not sure why you think it should be) and that 15 degrees sounds about right.

Seagrass
 

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2001 VDC/SC One of a Kind
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IF the scan tool is right and the cam values are uneven, it will cause misfiring. The injector firing is based on the bank 1 cam sensor, so if the actuator is not working proper or the oil control solenoid is stuck on bank 2, the timing is off from bank 1 and you get imbalance and misfires.

You can check the OCV resistance. Pins 3 & 4, the two opposite the lock tab, should be at about 7.5 ohm at a 65-70F range.

Otherwise you need accurate data via the scanner to know which is the problem.
 

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2010 Outback 3.6R 2014 Legacy 2.5i 2003 Legacy L special edition (retired to backup)
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15 degree at idle is about right, idle needs to be smooth...

you need to look at commanded vs actual values for the variable valve timing
 

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2005 OBXT Limited, VF37, STI intake, 5MT
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You likely won't see any solenoid code as they are pretty basic (continuity and/or circuit check); the ECU can't logically determine a likely cause of the issue. It only reports facts.

You are on the right track for the Bank 1 v. Bank 2 Intake Camshaft Advance Angle. At idle, it should read 0 (not the Final Ignition Timing, that will likely be near 10 BTDC) and they (B1/B2) should mirror each other VERY closely. Max should be near 25-30 degrees at the mid-range under high load. Maybe 1 degree or so of lag, but they should be even at a steady engine state (cruise, idle, light acceleration). Common diagnostic is to swap the solenoids and see if the angle lag (or misfires) follow to the other bank. Low oil pressure can also cause erratic operation, but you'd also likely see some over/under-advance codes (P0011, P0012, etc) and VVL pressure codes.

You should also keep an eye on the VVL system commanded on versus oil pressure readings. Could have a VVL solenoid failure or clogged solenoid. Less likely, but possible.

Do some data logging and report back.
 

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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '05 AWD Pontiac Vibe
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Discussion Starter #6
Thanks gents, I must have read incorrectly about the timing advance at idle. 15 degrees is actually what my Toyota would read at idle so at least this command value is normal.

Do the injectors read the intake or exhaust cam sensors from bank 1?

The values from the system check are definitely off between bank 1 and 2, the issue is I don't know a normal reading to compare this to. They are not really live date values as it is just a brief system check the ecu does approx every 5 minutes. If both bank 1 and 2 were checked at the same time then this is definitely indicative of an issue as the values are so far off form one another. I don't know if each bank is checked at a different time period, if that was the case then the values may not be abnormal as the cams would be at different degrees of timing at moments in time typically.

Either way using SSM and watching both intake and exhaust timing from both banks in real time is the proper way I'll have to go about diagnosing this, otherwise I'm still just guessing. Hopefully my VagCom cable comes in the mail soon and I can go about figuring this out.

According to the LegacyGT thread the OP did flush the engine as recommended by the service manual, he also tested the solenoid for resistance and with a 9V battery and it appeared to be perfectly fine. However the code would come up every 10 mins, but as soon as a new solenoid was installed the code never came back and his Legacy ran smooth again. Weird how the solenoid seems to fail but they seem to be a wear item at high mileage. I won't bother pulling mine to test them yet until I have seen was SSM has to show.
 

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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '05 AWD Pontiac Vibe
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Discussion Starter #7
You likely won't see any solenoid code as they are pretty basic (continuity and/or circuit check); the ECU can't logically determine a likely cause of the issue. It only reports facts.

You are on the right track for the Bank 1 v. Bank 2 Intake Camshaft Advance Angle. At idle, it should read 0 (not the Final Ignition Timing, that will likely be near 10 BTDC) and they (B1/B2) should mirror each other VERY closely. Max should be near 25-30 degrees at the mid-range under high load. Maybe 1 degree or so of lag, but they should be even at a steady engine state (cruise, idle, light acceleration). Common diagnostic is to swap the solenoids and see if the angle lag (or misfires) follow to the other bank. Low oil pressure can also cause erratic operation, but you'd also likely see some over/under-advance codes (P0011, P0012, etc) and VVL pressure codes.

You should also keep an eye on the VVL system commanded on versus oil pressure readings. Could have a VVL solenoid failure or clogged solenoid. Less likely, but possible.

Do some data logging and report back.
I had thought about swapping the exhaust solenoids and seeing what codes I get, and then intake solenoids if nothing happens. It is my understanding that for the 3.6R the exhaust solenoids are actually different where as the intake are the exact same and therefore interchangeable (not sure how true this is).

The current weather up here makes me more inclined to wait to get the cable instead of getting under the car and swapping solenoids! If I fail to get SSM running then swapping the solenoids out will be my last option.
 

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'10 3.6R Outback Limited, 2zr swapped Toyota Yaris track toy, '05 AWD Pontiac Vibe
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Discussion Starter #8
Alright, the cable was delivered to me today and after 2 laptops and a couple very frustrating hours I was able to take the OB out for a quick jaunt and log some data. I am using SSM so I am unable to actually log data I am basically keeping an eye on the lap top while under various driving situations. Below is a shot of the data at the end of the drive.



I had actually logged the intake solenoids as well but they were bang on matching one another so I ruled that out very quickly. I also checked the knock sensors and there was no recorded knock pulling timing so I also ruled out a bad knock sensor.

I have two questions based on the above:

Is bank 1 (passenger side) considered the Right hand side?

Is the above data enough to show a failed exhaust cam solenoid? I assume the right one appears bad due to it only maxing out at 25 degrees vs 40 degrees on the left side. That said my misfires are on bank 2 only (left side) so I an unsure about why this would be. I plan to data log tomorrow night with the wife driving but I wanted to see if this is enough info for any of you to be confident that one of the exhaust cam solenoids are bad.

In the 20 mins I was out driving I couldn't actually get the car to misfire at all. I had the cylinder roughness counters active for all 6 cylinders and for the first 10 mins it showed double digit roughness on all bank 2 cylinders and zero on bank 1 cylinders. This seemed to not really come back for the last 10 mins of driving. Another thing to note is during the first 10 mins of driving (it was up to temps) the right exhaust solenoid seemed to always stay around 10 degrees when the left one would be at zero.

The misfires have gotten more prevalent lately and seem to happens specifically when driving around 100km/h and the load on the engine increases slightly (going up a slight hill) and the car doesn't downshift so the rpm's are around 1750. If you give it a bit of throttle and force a downshift then misfiring goes away when the rpm increase (and therefore oil pressure as well).

Please feel free to let me know what you all think. I want to pick up a solenoid asap if that is the issue, but if this is not enough data to do so then I will have to try again tomorrow.
 

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2010 Outback 3.6R 2014 Legacy 2.5i 2003 Legacy L special edition (retired to backup)
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if you are facing the car, the left side is passenger side.
 

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Discussion Starter #10
if you are facing the car, the left side is passenger side.
I understand that, but what orientation does Subaru give when discussing left and right sides?

All my reading online says it is the orientation of the person sitting in the drivers seat. Meaning the left side is bank 2 or the drivers side.
 

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Discussion Starter #11
I went ahead and ordered the left side exhaust OCV/solenoid. I logged some more data on a longer drive this morning during my commute and although I could not get the engine to misfire or throw a misfire code, I was able to watch the exhaust timing retard/advance more closely. I gave THIS THREAD another read and it became a more clear that the bank 2 solenoid is failing but not enough to trigger a code or give me a consistent misfire.



Using Subaru's diagnostic procedure as posted in the above link, I should see both exhaust cams at 10 degrees of timing when I am at a steady state drive at around 1500-200rpms. While travelling on the highway (80-120 km/h) I noticed that bank 1 exhaust timing stayed right around 10 degrees. Bank 2 however constantly fluctuated a waveform of 0-23 degrees. I also monitored intake timing to see what a known good solenoid does to timing. Sure enough a good solenoid should keep timing relatively stable when at a constant speed and engine load of driving. The timing should not fluctuate like a bad O2 sensor does. My OCV doesn't seem to have completely failed but it appears to be on its way out - hence the no CEL except for the misfire code.

Because I wasn't able to illicit the misfire, I could not watch to see what actually happens during that time, but my guess is the solenoid on bank 2 gets stuck at 0 and this causes the misfires on that bank during higher engine loads. Chances are the OCV is gummed up and it sticking. This is also likely why during high rpm's (above 2500) the misfires go away. The higher rpm's increase oil pressure and I can actually watch the timing value somewhat stabilize on bank2 during higher rpm driving. It is during steady state driving (1750-2200 rpm) where the timing on the bank 2 exhaust continually fluctuates or bounces between 0 and 23. This is also likely why the max value is so much higher on the bank2 solenoid vs the good bank 1 solenoid.

*Be aware that there is a different part # and solenoid if your 2010 3.6R is built after May 23, 2010. I had to check the door jamb sticker on mine and since mine was manufactured in February of 2010, I needed the older one (part # 10921AA130)

I will post back when the new solenoid is shipped to me and I install it. I'm hoping this info helps someone down the road as the LegacyGT thread really helped me out by guiding me down the road of a proper diagnosis.
 

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Discussion Starter #12
Finally found the solution to the problem and have confirmed it with a long drive that previously threw a misfire code, as well as checking exhaust timing on SSM. The problem was a bad VVT solenoid on the exhaust cam bank 2 (left side) and the solution was obviously to install a new sensor. I picked up a Gates one off of Rock Auto for $72 CAD before shipping. It is made in China and my first choice was the Intermotor solenoid that was only $74 which is made in Poland but that had a few day delay.

Really interesting to note was that the old solenoid tested all within normal limits and showed absolutely no sign of failure. It tested at 7.6 ohms at room temp and when 9V were applied to it the internal valves moved the same amount as the new good solenoid. This is the exact same thing that was noticed by the OP in the LegacyGT forum link I had posted above.

Take note that I never actually had a code thrown specific to the solenoid (P0014 for example) I only ever had a P0302, P0304, P0306. The code only got thrown during long highway drives when engine load was increased (going up a slight hill) and it would go away after a brief time. I never experienced the constant CEL or poor running engine that other people with this issue stated they had. My problem did get more common over the past few months so I'm sure if I left it then I would have noticed many of these other issues.

*The only way I was able to detect what was causing my bank 2 misfire was by using SSM software and watching the exhaust cam retard degree and duty cycle percentage of both bank 1 and 2. Both degree angle values should follow almost identically and when driving at steady state on the highway the retard angle should be 10 degrees. What happened was my bank 1 angle was always fluctuating from 0-23 while my bank 1 angle stayed at a constant 10 degrees. When I did experience a misfire I never noticed anything out of the ordinary on any of the PID's. The only thing I saw was that the STFT would go immediately to +22% on bank 2 and -22% on bank 1. This was likely just a result of the multiple misfires causing the O2 sensor to read lean.

The take home here is that you may have a failing VVT solenoid that shows absolutely zero sign of failure except for an occasional Bank 1 or Bank 2 multiple misfire. The only sign you may see if by viewing the data in SSM and noticing that the cam angles do not match up perfectly. I forgot to take a picture of my laptop screen after my drive, but the important thing to note was that the max values for the exhaust cam retard angle were 20 and 22. Not 20 and 40 like they were before. Also both cam angles were always within 1 degree of one another, not fluctuating like before.
 

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Thanks for posting the solution, I am sure others will now be able to use the information to help resolve future misfire problems.

Seagrass
 

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2014 Subaru Legacy 3.6R, Venetian Red Pearl, EyeSight.
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2010 OB 3.6R 170k Miles

For the past couple months I have always felt my OB misfiring slightly between 1750 and 2200 rpm when going up a steady low hill...
My '14 Legacy 3.6R just started doing this. No CEL, no codes, no misfires logged that I could find, just obvious misfires under moderate load and sometimes at idle. I've been obsessing over fixing the issue since it started happening, so this write-up is great! Thanks!




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