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Old 03-21-2011, 12:22 AM   #1
ansonowicz
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Default AVCS VVT Angle Woes

After recently building my motor and able to break it in, I finally went for a tune. The tuner was perplexed by the slow boost times and inability to get power out of what would otherwise be a good setup.

He pointed out the following AVCS behavior. He put in a safe, reliable map so I can continue to drive daily until I get this resolved and return for a proper tune. The VVT angle actually fluctuates between 2-4 degrees while the other intake cams are moving along between 18-22 degrees. This tells me the solenoid is actuating and not just reporting 0.

I removed both OCV solenoids, wired up a 12v source to see it actuating properly. CHECK. Checked oil lines to the heads to make sure there aren't any obstructions or clogged filters, CHECK.


Is it possible for the Cam gear to be dissassembled to make sure there isn't any gunk in there and allow proper operation? Or should I just swap both of the Cam gears out? This build has exhausted my funds, so avoiding a couple hundred dollars in favor of some extra labor is fine by me.

Thanks in advance.
Anson



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Old 03-21-2011, 12:55 PM   #2
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anson...ill show Jon the thread and see what he says..
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Old 03-21-2011, 01:37 PM   #3
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you need thicker head gaskets.. .045 Cometics will do the trick


the difference in head thickness from machining is affecting the timing values.
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Old 03-21-2011, 01:44 PM   #4
twizhimself
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Old 03-21-2011, 01:46 PM   #5
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are you throwing any codes???
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Old 03-21-2011, 01:49 PM   #6
ansonowicz
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Not throwing any codes whatsoever. I'm using Subaru OEM master gasket set. It will cause one head to read less than the other? I didn't have the heads machined at all and they were still within spec using a straightedge.
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Old 03-21-2011, 01:51 PM   #7
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Thanks for the link...I'll have to call about getting 99.5 bore diameters if this is the case.
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Old 03-21-2011, 02:11 PM   #8
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Did you test the solenoid on the car? And if so what were the readings? Also it will need oil pressure to operate correctly. but I'm wondering if u do this test while car is running that it might cause Piston to valve contact if done incorrectly?
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Old 03-21-2011, 02:30 PM   #9
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Quote:
Originally Posted by wrxsubiemod View Post
Did you test the solenoid on the car? And if so what were the readings? Also it will need oil pressure to operate correctly. but I'm wondering if u do this test while car is running that it might cause Piston to valve contact if done incorrectly?

No, I didn't actually test in while in the car. I took the solenoid assembly out and applied it to a 12V power source just to see if the solenoid actuated. Sure it enough, it opened & closed, so the solenoid itself isn't bad. Now it's a matter of getting the right about of oil into the cam gear chamber OR the cam gear itself is stuck OR the above mentioned gasket thickness. I'm all ears.
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Old 03-21-2011, 03:09 PM   #10
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Yeah I would say a restriction or test solenoid input with car running should be the same voltage from ds and ps. If you got nothing it might be a pin loose. Or if there is voltage its a hydralic or mechanical issue
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Old 03-21-2011, 09:33 PM   #11
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Quote:
Originally Posted by ansonowicz View Post
No, I didn't actually test in while in the car. I took the solenoid assembly out and applied it to a 12V power source just to see if the solenoid actuated. Sure it enough, it opened & closed, so the solenoid itself isn't bad. Now it's a matter of getting the right about of oil into the cam gear chamber OR the cam gear itself is stuck OR the above mentioned gasket thickness. I'm all ears.
i would say to swap the solenoids from one side to the other and see if the problems moves to the other head...we had a car that did the same thing and turn out to be a bad solenoid.
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Old 03-22-2011, 01:11 PM   #12
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I'd really appreciate if you responded with the solution if you ever get one. I've been trying to tune a guys car for about 3 months now, and we keep having the same issue. Granted his is a JDM ecu on a USDM car so wiring also plays a part. But we have tested and/or replaced both cam sensors, both solenoids, all wires, and the ecu. Only things we have left are cam gears. I've heard that if the gears were put on with an impact it could damage them, though I don't know the truth to this.

Andy
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Old 03-22-2011, 03:17 PM   #13
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Quote:
Originally Posted by ansonowicz View Post
Not throwing any codes whatsoever. I'm using Subaru OEM master gasket set. It will cause one head to read less than the other? I didn't have the heads machined at all and they were still within spec using a straightedge.
decking the block pulls the heads closer together and alters timing. There are solutions other than juts thicker gaskets for solving the issue, now.

Quote:
Originally Posted by wrspeed View Post
i would say to swap the solenoids from one side to the other and see if the problems moves to the other head...we had a car that did the same thing and turn out to be a bad solenoid.
I was going to say to do the same thing.
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Old 03-22-2011, 03:21 PM   #14
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I should add that I had a similar issue on an 05 STi, though not as drastic(~2 & ~10) and it wound up being the cam gears. Bother were replaced and the car ran fine. Occasionally I see silly readings if, after flashing the ecu, the gas pedal is touched within the first 45 seconds or so of start up. The ecu does need to figure itself out after a flash. Not sure if any of this helps, but I hope so!

Andy
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Old 03-22-2011, 03:46 PM   #15
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Quote:
Originally Posted by elevenpoint7five View Post
I should add that I had a similar issue on an 05 STi, though not as drastic(~2 & ~10) and it wound up being the cam gears. Bother were replaced and the car ran fine. Occasionally I see silly readings if, after flashing the ecu, the gas pedal is touched within the first 45 seconds or so of start up. The ecu does need to figure itself out after a flash. Not sure if any of this helps, but I hope so!

Andy
yeah i usually get odd avcs readings after a flash, but after letting the idle learn itself again and i blip the gas they reset to 0 and function properly
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Old 03-23-2011, 12:08 PM   #16
ansonowicz
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UPDATE:


For whatever reason, I was thinking the solenoids were Left/right specific. Duh, that would be very unlike japanese engineering. Anyway, swapped the solenoids and timing was acting properly again. WTF? I put the solenoids back in their original position and they were still working properly....I got very confused.

But after driving around for a bit, I noticed there was coolant coming from the radiator cap. Just a bit sprayed unto the the underside of the hood. So I let it cool, checked all of the levels in case it needed to get burped. Went driving again for a few blocks under NO boost. No coolant, AVCS working okay. Yay.

Drove a few blocks again after letting it cool down, but this time WITH boost. Sure enough, some coolant was spraying under the hood. Not alot, but definitely not normal.

I'm hoping it's not head gasket issue and combustion pushing air bubbles into my coolant. Tuner was running dyno pulls for a couple of hours all day with no leaking issues last week, maybe "sidewayz" was right about HG. I'm going to drain and inspect coolant, perhaps add that combustion gasses detection thing in addition to visual inspection. Rainstorm is supposedly coming, so I might not get to it for a few days.

Last edited by ansonowicz; 03-23-2011 at 12:37 PM.
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Old 03-25-2011, 06:48 PM   #17
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car looks like its gonna be outta injector and MAF when you turn the boost up....

84% idc and 4.6 MAFv at 13psi....
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Old 03-25-2011, 10:54 PM   #18
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Quote:
Originally Posted by Phatron
car looks like its gonna be outta injector and MAF when you turn the boost up....

84% idc and 4.6 MAFv at 13psi....
Thanks for the heads up. The boost was scaled back as a temp safety precaution. It's usually about 84% at 20psi. Tuner simply "select all" and replaced with 13psi.
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Old 03-31-2011, 03:34 PM   #19
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Swapped solenoids everything was good. Swapped them back, everything still good. Electrical gremlin? I guess so. I found a crack in my radiator, so once that was taken care of, everything is working like it should now. Time to head back to the tuner.

Thanks everyone for your tech advice
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Old 03-31-2011, 07:36 PM   #20
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still have the banjo filter on those avcs banjos? check those.
a buddy removed one and left the other one with a filter.
AVCS was acting a bit funny.
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Old 03-31-2011, 07:50 PM   #21
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Originally Posted by Nuke209 View Post
still have the banjo filter on those avcs banjos? check those.
a buddy removed one and left the other one with a filter.
AVCS was acting a bit funny.
The banjo bolts were replaced with non-filter types.
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Old 03-31-2011, 08:27 PM   #22
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The banjo bolts were replaced with non-filter types.
that's nice to know.
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Old 03-31-2011, 11:41 PM   #23
elevenpoint7five
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I guess I'd better report back as well. The car we were having issues with ended up having bad cams/cam gears. Long story short, the nub on the cam was bent because the gear was impacted on by someone not allowing the two sections to spin independently.

Glad you fixed your issue!
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Old 01-13-2013, 05:59 PM   #24
robednz
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Default ej25 vvt cam gear fault

not sure if this is the right area, my 1st post in this forum, i have rebuilt my ej25 and can't get the right hand cam sprocket to re time properly [all the marks line up but it won't run, it will run for about 2 seconds the backfire and spluuter], i noticed the inner part of the pulley turned when i was loosening the center bolt and didn't return . can anyone tell me where the vanes on the pulley rotor be set , they were fully clockwise looking at the front of the pulley, we removed the cover and set the rotor in the center of it's travel and put it all back together but it still won't run and makes a clacking sound on the right hand side, so thinking maybe it needs to be set fully counter clockwise.. have checked solenoids and spool valves all working ok, it brings up a vvt error in the ecu .. does it pump oil to one side at low rpm so as to hold in position then to the ther side as the rpm rises
any help really appreciated
rob
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