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Old 05-02-2011, 09:02 AM   #1
wakeboardin
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Default Intake AVCS problem - Please help

I own a 2004 Forester XT 5 spd

Not to long ago I had my engine rebuilt by a local engine shop. I have since added everything to the block and put the engine in the car. I am now in the process of working with a tuner to create a break in map. Here is what has been done:

Long block:
-rebuilt motor over bored w/ 100mm weisco pistons and manley H rods
-clevite bearings
-supertech valve train (nitride intake valves, inconel exhaust valves, dual valve springs, titantium retainers, replacement seals and guides)
-mild port and polish work on the head
-arp heads studs
-cometic head gaskets
-11mm oil pump
-stock crank and cams
Engine related:
-Perrin fuel rails
-TGV deletes w/ gasket matching to manifold and heads
-Light porting on intake manifold
-08+ sti intercooler
-APS SR40 turbo
-PE 850 injectors
-walbro 250 fuel pump
-APS hard turbo inlet pipe
-SPT intake
-Moroso oil pan and pickup
-all new idlers and pulleys and water pump
-gates racing belts (timing, acc, ps)
-grimmspeed 3 port boost controller
-Perrin signature series recir BOV
-Maddad exhaust and downpipe
-no name headers and uppipe (reinforced by my welding shop)- w/ heat wrap


The problem I am having is that I am getting some odd AVCS results when logging. If I am correct, I believe the AVCS Intake L+R should pretty much be in sync but in my case they are not.

I was asked to do 60sec idle, 60 sec @2000rpm and 60sec @3000rpm.

I rechecked the timing and everything is good.

I have done some searches regarding subaru + AVCS and there is limited info. Please feel free to chime in on what it could be or what I should try out. I can't change back the injectors without a lot of work as the plugs had to be changed for the PE injectors.

Any and all help would be appreciated so I can get the car back on the road.

Here is a sample of my first log. I have just taken samples at idle, 2000rpm and 3000rpm . You can see that at first AVCS Left shows results, but then it is just zero.

http://i1131.photobucket.com/albums/m556/wakeboardin/7771e2bc.jpg
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Old 05-06-2011, 02:03 PM   #2
spotter29
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pull the solenoids and make sure they are clear/clean. many times during rebuilds the noids get funked up while they are uninstalled. happened on my 257 when i did a rebuild. worth checking out (could be a simple fix)
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Old 05-14-2011, 07:30 PM   #3
wakeboardin
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So I think I may have exhausted most of my options for checking for a problem.

I have been reading often that the intake AVCS should move in sync with each other within a few degree. In my case when there is anything more than idle rpms the right intake avcs goes up to around 10 and the left intake avcs is always 0.

So far I have done the following in the order:

- redid the timing in case I was off by a tooth.
-swapped Oil control Solenoids from one side to the other to see if the problem switches sides.
- removed intake avcs cam gears , dissasembled, cleaned and reassembled. redid timing
- Swapped Cam position sensors from one side to the other.

In between each of the above I ran the car allowed it to warm up and then logged. I got the same AVCS results as above each time.


My current tuner (etuner) seems to think the AVCS is causing and issue. I don't know enough about tuning to know the difference.

Today I talked with a local tuner, who I have done some rallycross with and he seems to think that since I am not putting any load on the engine yet
( idle/2000/3000/idle logs) that the AVCS really don't matter yet. He also said that subaru has a set differential max between the left and right intake avcs and if it goes over that it will cause a check engine light. Is this possible? I am not getting any CELs.

Does anyone have any non driving logs they can share so I can see what the avcs generally do at low/no load.
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Old 05-15-2011, 09:26 AM   #4
elevenpoint7five
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Try resetting the ecu, then turn the key to on and let it sit for ~10 seconds. Next start the car and don't touch ANYTHING! No gas, no steering wheel, no shifter, nothing! Let it sit for about 2 minutes. Then, you'll need to drive it. AVCS won't work properly if it sees the airflow, coolant temp, or load aren't within certain conditions. So if your MAF scaling is way off, or the car isn't to temp, or there is an odd load on the motor, it might not work. The reason for resetting the ecu and letting it do its thing for 2 minutes is the AVCS has to be checked by the ecu and then zeroed out before it can function properly.

If none of this helps, I would bet you have a bad cam gear. Hopefully you're using a special tool to put them on and not just impacting them on. When using an impact, you can, and usually will, over tighten the bolt causing the center section to seize up while the outer section still spins when the motor is turned over.

Good luck!

Andy
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Old 05-16-2011, 10:03 PM   #5
jaxscuby
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also check banjo bolts for screens..remove same..
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Old 05-17-2011, 08:34 AM   #6
wakeboardin
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I forgot to mention that before all this I removed the screens from all the banjo bolts.

Update.

I tried the above steps and still had the same issue.

I also tried flushing the system with oil (i.e. oil change/ run ten minutes/ oil change) To make sure there was no contamination in the oil or engine components.

I tried the above steps, and did not touch anything but got the same results.

When install the cam gears and reinstalling them after dissassemably I put them on, thightened the bolts by hand (while holding the cam gear). Once the timing was complete I put it in third, had someone push on the brake and tighten the cam gear bolts using a torque wrench using the torque setting from the FSM. When doing this I tighten the belt guids all then way down to make sure the timing belt wouldn't skip teeth. I also rechecked timing after to make sure I was still on.

After talking with two tuners I decided it was best to drive it with a light amount of load to see if the problem still occurs. It does, but here is the strange part. It used to be the left cam gear that was sitting at zero and the right cam gear that would adjust, but now the right gear is at zero and the left cam gear moves. I have repeated this test several times and it happens every time. As well after two or more consecutive drives without resetting the ecu, a cel will come up. P0021

So my problem is, if it is a cam gear which one is actually at fault? As well I have dissassembles both of these and cleaned them well. There where no flaws or issues with them and they visually looked perfect once they were cleaned.

Any suggestions would be helpful. If I could say with 100% certainty that one of the cam gears was at fault I would replace it. But with the wierd results I am getting I am reluctant to spend $200 on something that may not imporve the situation.
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Old 05-17-2011, 11:11 AM   #7
SeeeeeYa
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Why was your motor rebuilt... that is, was it a preemptive move or had it mechanically failed. I ask to rule in or out residual oil passage contaminants.
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Old 05-17-2011, 11:34 AM   #8
wakeboardin
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My engine was starting to get alot of smoke from the tailpipe when it idled for longer than 30 sec. A leak down test was done and 2 cyl failed leakdown at the exhaust valves.

On futher inspection when dismanteling I found my turbo was shot as well. Way to much shaft play. So turbo was replaced and engine was rebuilt. Since it would have been my first rebuild and it is my daily driver I left it to local professional engine builders to build the engine. As part of the process they were supposed to fully clean the block before reassembly. Hopefully they did a good job.
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Old 05-19-2011, 12:56 PM   #9
SevenLevin
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problem solved. ****ing cosworth!

Last edited by SevenLevin; 09-19-2011 at 06:22 PM.
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Old 05-19-2011, 07:18 PM   #10
wakeboardin
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SevenLevin- So what are you thinking of doing next? Could it really be your cams causing the problem.

Still not sure where to go from hear. I am going to check the wiring from the ecu to the sensors next. If there is no problem there I may consider buying a used ecu. I feel as though I have checked everything mechanical and that it must be an electrical glitch now.

Any more thoughts on what to do next would be greatly appreciated.
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Old 05-24-2011, 11:39 AM   #11
PoZeR
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I had the same type of issue after a timing belt change at the dealer.
After that day my AVCS was way off the car ran like crap, sometimes I would get back fires.
The dealer checked timing for me 3 times and even showed me all marks were on.
After me engine blew for other reasons I found this when pulling my cam gear.

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Old 05-25-2011, 10:23 AM   #12
wakeboardin
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Sucks that your engine blew.

The pin alignment is not an issue in my case as I have checked it several times but I am worried about putting to many kms on it without getting the advanced timing resolved.
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Old 07-05-2011, 01:38 PM   #13
azn2nr
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im having the same issue and i have taken the same steps. mine stopped working randomly last year adn i just ignored it and turned the code off. i just had my motor rebuilt and the issue is still there. im thinking electrical but is there a fuse for the solenoid that can be changed?
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Old 11-14-2013, 08:50 PM   #14
Irv Weissmanhowerton
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Im having problems very close to this too, just after an engine build, If I could say for sure its a cam gear or 2 I would do it,

When I do a pull, my left side intake avcs only gets up to 4-6*, while other side is pretty on par up to 25 or so, I believe the right side should have been at 30-35 tho
I have had my newly put on kelford cams checked, swapped solenoids with a working sti, made sure no filters,

help, please, I need avcs, losing about 1000rpm I think without it, did as much as I could in the car but motor is on stand now waiting for solution, Is it the cam gear(s)? Someone was a little rough on it last removal, Also if its saying left intake, which is driver, is the log saying left, the same as the cam gears markings saying left?

Last edited by Irv Weissmanhowerton; 11-14-2013 at 11:36 PM.
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Old 11-16-2013, 10:12 AM   #15
Irv Weissmanhowerton
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Bump. Anyone got any advice on my post above this one?

Seems more people go in built motor then this section
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Old 11-16-2013, 03:12 PM   #16
SeeeeeYa
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Quote:
Originally Posted by Irv Weissmanhowerton View Post
Bump. Anyone got any advice on my post above this one?

Seems more people go in built motor then this section
Go here: http://forums.nasioc.com/forums/show...078290&page=28

Post your situation. Someone will reply with advice.

Contact this vendor: http://forums.nasioc.com/forums/member.php?u=178047
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Old 11-16-2013, 05:00 PM   #17
Hyper
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for experiment sake, I would zero out the AVCS table in your ROM, upload it and do a log again

if you get similar readings, it means the cams are being pushed mechanically (oil pressure) and are in fact not working, which would indicate a wiring issue (avcs is ground sensitive, or you NPS might be disconnected/broken)
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Old 02-27-2021, 11:11 PM   #18
thefxtguy
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Anyone resolve this AVCS issue?
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Old 03-01-2021, 03:53 AM   #19
alexmartynyuk
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Just an FYI for people cleaning cam gears at home, it is extremely easy for them to bind even after cleaning. When putting them together you need a tool to align the cam gear when torqueing the bolts. Here is a short video talking about it and why its important and if this step is skipped it is very likely that you will endlessly chase your tail having AVCS issues.

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