AVCS VVT angle out of sync diagnosis MY07 GT B

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AVCS VVT angle out of sync diagnosis MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 5:20 pm

This info is pasted from the Group Buy 2.5T AVCS inlet cam gears and OCV solenoids thread

How to change out your OCV's:
viewtopic.php?f=10&t=30105&p=407081#p407081

Symptoms of AVCS out of sync issues:
Rough idle, random flat spots, hesitation, stalling on takeoff, whole car rocks just off idle at around 1300rpm if held at those revs, poor economy.
The issue may be experienced independently of OVC CELs.
Factory diagnosis of my issue reveals the system is working in terms of its feedback loop, it's just unable to operate correctly due to clogging, jamming or wear and tear of one or more of the components.
Logging my Lib reveals laggy VVT operation on the RHS bank (turbo side) during city driving, and oscillation on the RHS bank from 0-51 degrees when cruising in 6th.

Background:
The AVCS system on the 2.5T is implemented to enhance power and economy.
The system is somewhat prone to failure, mainly limited to one side/bank of the engine.
These failures can be caused by a variety of issues including but not limited to oil and long term wear and tear.
Failure of the system is not usually catastrophic, but power and economy may be limited from the optimum possible.

From research:
- an oil/filter change has been reported to have fixed mild issues.
- the various electrical plugs and looms relevant to the system should be checked as should battery condition/connection.
- intake cam gear sensors may become dirty and require cleaning but rarely require replacement.
- OCV valves may become clogged with oil sludge or debris, or become worn, requiring at least cleaning but more commonly replacement.
- OCV banjo bolts and or filters (still unconfirmed) may require unclogging
- AVCS inlet cam gears may become blocked with oil sludge or debris or the actual mechanical parts and seals etc. may be damaged preventing correct operation.
- the issue has been linked to phantom knock, presumably noise from struggling cam gears.

Suggested fixes:
UEC, oil flush, oil and filter change.
Inspect, clean and or replace OCV solenoids.
Inspect and clean intake cam sensors.
Replace intake cam gears and do a timing belt service.

Why replace intake cam gears:
The specific example was reported on LGT, a small piece of metal was fouling the inlet avcs cam gear so it would either be on 0 or stuck on 40ish as soon as it saw oil pressure.
Your car has AVCS out of sync issues etc that weren't fixed by cleaning or replacing the OCV solenoids, removing, replacing or cleaning the OCV oil feed line filters, or by cleaning the inlet cam gear sensors. Or if low oil pressure, by checking the oil pickup. Or if hesitation, checking your MAF for cleanliness.
If you have slight AVCS out of sync issues and your oil light stays on for 5-10 seconds on start up, check the condition of your oil pickup: it may be fatiguing.
Check your battery connection and condition as poor battery performance can affect the OCV solenoids.

When to replace intake cam gears:
You have an upcoming timing belt service, engine rebuild, new heads etc. and want to change out all related items for long term reliability.
Or you just want your car running 100%.
A timing belt change is required when replacing the inlet cam gears.

To be sure log your car:
Buy or borrow a Tactrix and just log RPM, Speed, and the L & R VVT, OCV duty and OCV voltage parameters.
Log warmup, 60 sec of stationary in-gear 2K rpm, 60 sec of stationary in-gear 3K rpm, then driving below 70Kph, then some freeway K's.
Open logs in ECUedit or Megalogviewer Lite and look for lag or oscillation in the VVT angles.

If they are way out of sync its the inlet gears, solenoids or sensors.
If just a little out of sync: check your oil pickup, oil level and or battery condition/connection.

What does this issue affect and do I need to fix it immediately:
AVCS is implemented for power and economy, thus the issue will affect those aspects negatively: ballpark figure 20%.
Unlike the 2.0t (where the issue of blocked filters in the OCV oil lines would affect flow to the turbo, leading to blown turbo bearings) the issue may not be quite as severe on 2.5's, with the aforementioned reduction in power and economy being the primary effect.

Thus if your timing belt service is too far away or is presently too expensive, consider changing out your OCV's and cleaning/inspecting your intake cam sensors as this operation is independent of the timing belt and is even DIY-able.

Long term prevention:
Research suggests that a shorter oil change interval than recommended e.g. at 5K may be beneficial.
Some recommend doing shorter OCI's along with using an oil with a more aggressive detergent pack, e.g. Delvac MX 15W40.
The ultimate solution could be the addition (and extra complication) of 1 micron bypass filtration.

Let me know if I've missed anything! Cheers, BBB

Original Post:

Logging for my tune revisions is revealing "possible filter basket is dirty/clogged in LH solenoid"...
I'm reading the Service Manual and googling the fix, and will document my progress of course!

Advice proffered: "Solenoid is a 17mm bolt, dont loose the washers! Remove bolt and use a pin or similar to remove the basket. They can be removed completely if required."

Research: "AVCS solenoids/gears are easy to clean. pull out the solenoid, take the cover plate off where the solenoid attach to the heads. Easy clean. AVCS cam gears are also easy to take apart and clean out. Don't forget to clean the cam oil holes as well."

I'm intending to have a go at just the solenoid first, I'm assuming its LH = AUDM passenger side so should be reasonable easy to get to.
Should I also "take the cover plate off where the solenoid attach to the heads"???

If flushing/removing the AVCS filter/oil flush/oil + filter change doesn't work, I'll be moving on to "AVCS cam gears and cam oil holes" if the latter is not beyond my capabilities.
Any advice most welcome! I'm still googling... :D

Are there banjo filters in 2.5T libs?

You'd have to ask someone who tears these engines down often.
But as far as we know, based on basic research, mostly from US sites eg LGT, the 2.5T has them behind the LHS inlet cam gear, and on top of the block under the turbo inlet tube.
They're there for a reason, eg if you spin a bearing, it can keep debris out of the turbo and ocv's.
They can also be removed with no ill effect.

If there is a filter, its at points 3 (x2) in this diagram.
http://opposedforces.com/parts/legacy/e ... tration_1/
Intriguingly the RHS oil supply line in the diagram looks more like what you'd find on a preFL, with the union screw on the back of the LHS head.
I'll check my spare block next time I'm at the garage, where its sleeping in a container.

PreFL RHS style:
http://legacygt.com/forums/showthread.p ... ?p=2377798

PostFL RHS EJ255:
http://legacygt.com/forums/showthread.p ... l?t=200717

PostFL LHS EJ255: see the re re re post of HammerDowns filter fun.
http://legacygt.com/forums/showthread.p ... 89p71.html

But don't stress, 99.99% its going to be your OCV's. Chances are... there are no filters in the postFL 2.5T.

And in almost all cases, swapping out the OCV's is the fix, not going hunting for banjo filters.

I feel for you, my car was the same when I bought it at 150K: shithouse.



A few Throttlehappy tunes, 2x new OCV's, 3" tbe, pump, filter, airfilter, STS, ShockWorks and some other junks later its an on-point dream boat!




.
Last edited by bigBADbenny on Fri Jun 05, 2015 8:59 am, edited 9 times in total.
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Re: AVCS solenoids cleaning MY07 GT B

Postby bass_straitener » Fri Jan 11, 2013 6:36 pm

Ben I'd check with Subaru if the filter has already been removed.

I keep hearing stories of Subaru removing these filters during services due to quite a few reporting problems.
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 7:55 pm

Thanks Bruce!
I'm sure Docklands STi will have it all on record ;).

So I put google and the WSM down for a sec and once warmed up, logged just the:
Intake VVT Advance Angle Right (degrees) Intake VVT Advance Angle Left (degrees)

0 0
2 0
3 0
6 0
8 0
10 0
12 0
14 0
14 1
15 1
17 1
17 2
19 2
21 2
21 3
21 2
22 3
23 3
24 3
25 3
26 3
27 4
28 4
28 5
29 5
30 5
31 6
31 6
33 7
33 7
33 7
34 8
33 8
33 9
32 9
28 9
25 9
17 8

^^^That's a stab of the throttle to around 3000 rpm... Proof indeed!

I took off the engine cover and spent minutes trying to nut out where the LH ACVS solenoid might be...
Best bet is that its under a bunch of stuff including a metal guard for the fuel rails (may have a blue plug to rear?), within a triangle bounded by the oil filler tube, the air pump and the battery.
Image
^^^Likely looking 17mm-ish bolt
Image
^^^Blue connector
Image
^^^General area from the LH guard
All three of which may need to come out, pending a read of the procedure in the FSM. (anyone know where to find MY07 FSM specifically?)

Choices:
A: Do an UEC, oil flush, rinse with mineral, new synthetic oil and oil filter.

B: get to the solenoid, clean it, then do A... (or replace the solenoid)

C: Line up a mechanic to either do, or help me do A & B...

D: Do A,B,C and also get the replacement rocker cover gaskets (as recommended by STi last service) put in both sides...
Also doing B on both sides :P

I'm due for another service in 3000K.
I also idled the car briefly without the oil cap: thankfully no smoke, hoping its all fine!
Any advice valued :-)
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Re: AVCS solenoids cleaning MY07 GT B

Postby <GB> » Fri Jan 11, 2013 9:02 pm

I've had good success cleaning them our on other cars at work
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 9:09 pm

Pm sent lolzzz .
Btw: which option would you recommend? :-)
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Re: AVCS solenoids cleaning MY07 GT B

Postby <GB> » Fri Jan 11, 2013 9:18 pm

How many km your car done and does it have full service?
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 9:29 pm

Around 174K full Docklands STi book from new :-)
Next due @ 178K...
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Re: AVCS solenoids cleaning MY07 GT B

Postby <GB> » Fri Jan 11, 2013 9:50 pm

bigBADbenny wrote:Around 174K full Docklands STi book from new :-)
Next due @ 178K...

So oil changes every 10k?
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Re: AVCS solenoids cleaning MY07 GT B

Postby Kekotic » Fri Jan 11, 2013 9:54 pm

<GB> wrote:
bigBADbenny wrote:Around 174K full Docklands STi book from new :-)
Next due @ 178K...

So oil changes every 10k?


Should be every 5-6k for turbo according to the Gurus on this forum :D
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 10:09 pm

I'd have to agree... Now.
At this stage I'm looking to get this all sorted ASAP.
Considering some oiling upgrades at the same time, eg pickup, bypass filtration etc...
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Re: AVCS solenoids cleaning MY07 GT B

Postby <GB> » Fri Jan 11, 2013 10:19 pm

I'd do them at 5, I did like 3k in mine last service lol
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Fri Jan 11, 2013 11:06 pm

And add to option #4: AOS install...
Ill grab some OEM replacement intake side hose clamps, filter, crush ring and DIY it all in one go...
Will be studying the related FSM procedures in depth, again!
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Re: AVCS solenoids cleaning MY07 GT B

Postby msgofast » Sat Jan 12, 2013 7:12 am

What is the issue? never say what it is or isn't doing just you picked up and issue?
Cheers
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Re: AVCS solenoids cleaning MY07 GT B

Postby bigBADbenny » Sat Jan 12, 2013 7:43 am

Cheers!
The car runs fine IMHO, it's in the process of remote tuning with Matt for 3" dump & mid to modded STi sedan muffs. :wink:
Other mods are a now-properly sealed HKS air filter and a dw fuel pump & new in tank filter.

The tune revisions so far have been aiming to accomodate the exhaust mods, reduce overall peak boost levels, reduce DBW max requested torque, and once that's done to reduce popping on the overrun.

Matt spotted the avcs discrepancy via regular logging.

The Lib is at 174K, uses around 0.3L of oil per month, maybe rocker cover seal on LH side.
Inspecting the area I noticed oil weeping around the base of the oil filler tube, so ill remove and inspect that - I can't see a gasket there so I'll see what's in the FSM related to that.

I took another look this morning and the 17mm bolt should be accessible when the battery and the plastic air pump tube are removed. Planning to remove that this weekend. Then UEC & oil & filter change...
Open to any advice! :-)
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Re: AVCS solenoids cleaning MY07 GT B

Postby 3rspecb » Sat Jan 12, 2013 8:38 am

Not good news BBB, hoping that's the issue and can sort out quickly.
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