Attn: '04 forester XT, Sti, and Baja turbo owners
 

TSB on poor idle caused by a filter in the oil line to the avcs

http://www.scoobymods.com/forums/showthread.php?p=20694

Just checked mine and both filters had dropped - did the tsb in about 30 minutes and she idles smooth as the svx now.

Matt have you any links to info on the variable valve timing on this engine. I'd like to read a bit about it.:)

Harvey.;)

Harvey,
Check in my "Under the Hood" folder in my locker. I've got a .pdf file from Subaru on the AVCS.
-Bill

Thanks Bill, tells how the cam is moved, not much else.:)

Harvey.;)

isnt that all it is? Movement of the cam onto another lobe? Same way VTEC works for example my 97 GS-R uses three lobes, one for low rpms, then 1st stage VTEC around 4200, and another for 2nd stage at approx. 6100. And all is operated by an oil pressure solenoid.

No this just changes the position of the lnlet cam to the crankshaft position. Advances or retards it.

Harvey.;)

this is in the LGT.com tech reference:

AVCS & AVLS
Subaru has been adding some 'active' systems that in addition to the normal operating action of the engine are able to vary certain components to increase power and efficiency. Two of these systems, AVCS (Active Valve Control System) and AVLS (Active Valve Lift System) are very new to Subaru, with the latter being new this year and only available on the EZ30R as far as we know.

AVCS is a system that works with the cams (usually only on the intake side where the most benefits are shown) to adjust the duration of the intake valve opening, closing, and rates of change depending on what the computer determines according to sensor input. The AVCS system is actuated through oil pressure from the engine, which is sent through a computer controlled valve and then directs oil into an AVCS actuator to advance or retard cam timing in respect to the cam sprocket. The best thing about the system is that, the same heads can be used with or without AVCS activated. It’s just an auxiliary system in essence.

AVLS is another new technology to help improve volumetric efficiency. While AVCS can alter the cam duration and angle, either advancing or retarding the valve timing, AVLS is able to use two different profiles to alter the valve lift. The EZ30R is the first Subaru engine to use this technology. Instead of using a system like Honda’s VTEC with two cams, Subaru uses a double-profile single cam to control the same parameters. Much like the AVCS setup, AVLS actuates the switch between low and high lift lobes through an oil-actuated system. This system uses a double-tappet (the components which is in contact with both the valve and cam as shown below.) The switchable tappet switches between the low-duration and high duration generally in the 2,000 to 4,000 rpm range depending on ECU input (much lower than VTEC) allowing the EZ30R to breathe better at high rpm and improve low-rpm torque as well as emissions.

A good description is also offered in this press release:
http://subaru.com.au/news/?newsid=11894

So its not as invasive as VTEC then... different idea.