AVCS VVT angle out of sync diagnosis MY07 GT B

[bass_straitener]

Of course Bruce, as usual you are correct and I apologize for my impudence

Yes don't do it again.

Perhaps a revision from your tuner will fix this issue.

You can only hope.

[bigBADbenny]

Stay "tuned" pending a chat with the STi service manager

[jp928]

does this help at all?
http://legacygt.com/forums/showthread.p ... ml?t=18887

jp 08 gtb 6mt wagon, no issues so far

[bigBADbenny]

Ill add that to the research list, tks!
Really intrigued, USA forums point to solenoids apart from 1 instance where someone had a bit of metal stuck in the avcs cam actuator (stuck open or closed)...
Local research points to oil pressure/viscosity or replacing the avcs cam gears.

[KiDo_Tuning]

Ill add that to the research list, tks!
Really intrigued, USA forums point to solenoids apart from 1 instance where someone had a bit of metal stuck in the avcs cam actuator (stuck open or closed)...
Local research points to oil pressure/viscosity or replacing the avcs cam gears.

Vince Rigoli replaces solenoids. Issue gone in car I tuned this morning

[bass_straitener]

Stay "tuned" pending a chat with the STi service manager

Any update or learnings from your meet with the STI manager?

[bigBADbenny]

He wasn't in last Friday alas...
I will meet him to discuss the issue soon.
Still taking logs but not yet the complete schedule as outlined previously. (Still ASAP)
Kinda bugs me that one banks VVT angle oscillates at a completely different rate to the other when cruising in 6th.
Ready to drop the oil, considering doing some sort of mineral + additive flush (ATF or nulon) then Syn: I have nulon 10w40 on hand but thinking something heavier?

What's in yours right now?
Did MSR need to take the issue into account at all, as regards your tune?

[bigBADbenny]

My Lib is off the road with another smallish issue , hoping to use the downtime to complete more suspension mods
In the meantime I'd like to summarize (again) the research and valued advice proffered:

Thicker is recommended for masking the out of sync AVCS inlet cam gear issue: 10w40, 10w60 or even those in 15w...
Delvac or similar oils with an aggressive detergent pack may help too.
From research, there are no filters in the AVCS control oil lines in postFL 2.5t.

The ultimate solution is apparently just to replace both avcs inlet cam gears, and use an oil with agressive detergent pack on a sub 5k OCI (eg: Delvac 10w60).
Not the oil pump, not the avcs solenoids although the latter is supposed to be relatively easy to do...

I've seen proof in my logs, the AVCS inlet cam gear angles are closely matched under acceleration, but deviate (one side's angle oscillates through its entire range, whilst the other holds steady when cruising at 100kph within a 2300-3500rpm rev range, 4th through 6th.

Here's the graphed log, if you check out the revs (lower graph) I accelerated to 100kph, drove in 3rd @ 100kph, cruised at 100kph in 4th, 5th, 6th, then drove in some traffic at the end of the freeway... Full size, rollover for notes...
That was using a log-to mSD card logger profile as supplied by TH (via Chaotic).
Regardless, its clear the the AVCS VVT angle L/R oscillation issue worsens the lower the revs...
If heavier oil doesn't mask or fix the issue, I may take a peek at the solenoids before replacing both inlet cam gears, the latter next timing belt service...

[Shaheenis]

Benny, can you explain how you expect a heavy detergent and heavier oil to help? What is the theory? Also, why replace the gear, what can go wrong with it and can it be done with cam pulley still on car?

After reading the linked legacy forum and the description from the mechanic when mine was replaced (in thread viewtopic.php?f=18&t=20284 ) it appears that these are two different issues. The OCV replacement seems to fix the stalling issue but hasn't fixed the idle on mine. Perhaps the idle issue lies with the gears? Guess I should log this and see what it tells me. I have had no CELs..

[bigBADbenny]

Clean thick oil can't make the issue any worse...
Heavier oil = more pressure to activate the valve in the cam gear.
Detergent to clean the seals etc in the avcs mechanism.
The avcs mechanism is 3 hydraulic chambers in the cam gear - when oil is let in by the solenoid it changes the cam gear angle in relation to the camshaft. This changes the timing on the inlet valves

Obviously I'm getting other opinions as I barely notice the symptoms!
But it does affect the tune apparently.
Please make a similar log

[3rspecb]

sorry to hear about the bricked ecu Ben. Its the one thing that makes me nervous with this whole caper. Hope it's sorted quickly..

[bigBADbenny]

Thanks G, I guess I glossed over the "don't ever turn the key bit when reflashing" bit in the manual.
That's the thing I enjoy about modding my rig, any time I loose my patience or get greedy I get massively kicked in the arse with a carmic boot.




And that's just Brian lol.


Planning to build a bench reflasher sometime soon too

[Shaheenis]

Thanks dude. Not all of my symptoms are the same. I really only have rough idle/wobble that by no means is extreme, quite mild actually but I would expect in a fully serviced engine of it's age to run perfectly smooth, especially with no mods. Sometimes when accelerating part throttle and constant throttle, the acceleration isn't smooth but it is better under full noise. It is KiDo tuned so hopefully not a tune issue. I am getting the 100k service this week so I was planning on asking them to change plugs early and to use a 10/40 full synthetic. I have read ome posts on the legacy forum where mechanics are recommending against synthetic oil for these engines but perhaps they don't know what they are talking about. Does anyone use engine flush between oil changes?

[bigBADbenny]

I'd use a flush immediately before an oil change if at all.
I'm still researching oil flushing:
Kiks dino + ATF flush (scant details on this forum)
Nulon etc oil flush
1/3 can UEC in the oil 500klm before oil change (LGT)... Etc.

Opinion is also that its uneccessary to flush.

Subaru UEC is recommended between oil changes as is Subaru fuel additive.
Got a log?

[bosc0]

Thanks dude. Not all of my symptoms are the same. I really only have rough idle/wobble that by no means is extreme, quite mild actually but I would expect in a fully serviced engine of it's age to run perfectly smooth, especially with no mods. Sometimes when accelerating part throttle and constant throttle, the acceleration isn't smooth but it is better under full noise. It is KiDo tuned so hopefully not a tune issue. I am getting the 100k service this week so I was planning on asking them to change plugs early and to use a 10/40 full synthetic. I have read ome posts on the legacy forum where mechanics are recommending against synthetic oil for these engines but perhaps they don't know what they are talking about. Does anyone use engine flush between oil changes?

Mine is the same, lumpy cams ftw Tim! Also awaiting a tune one day to see if it can rectify the rocking.