Rosssub

Could be a wiring/install fault tripping the CEL, just a faulty AFC tripping a CEL or a genuine OEM sensor fault. Start by checking what CEL fault codes coming up. See the section in here on manually reading codes if you're not sure: http://www.scoobypedia.co.uk/index.php/Knowledge/ReadingECUCodes

Each engine/setup reacts to a venting valve slightly differently. Then all valves are slightly different too, diaphragm size/spring rate/port size/Vac hose sizes. So some venting BOV will dump more metered air than others. Some people get flames and over run as you've mentioned, some get noticeable backfires on decell and some get nothing more than a drop in idle revs when the throttle first closes.

Got them through a privately owned shop that uses the same suppliers. BNT has them, some prices and part numbers on the first page.

Manual diagnostics start on page 3492: SELECT CONTROL PANEL TO SELF-DIAGNOSIS MODE. 1) Turn ignition switch to OFF. 2) While pushing “AUTO” and “FRESH/ RECIRC” switches, turn ignition switch to ON. 3) Make sure that all characters on the display blinks four times.

Pic's in here: http://clubsub.org.nz/forum/showthread.php?45977-Changing-BE-BH-Fuel-Pump&p=578671#post578671 Filter - 42021AE010 O-ring - 42025AE020 http://opposedforces.com/parts/legacy/en_b12/type_11/intake_and_supply_system_turbocharger/fuel_tank/illustration_3/

These guys: http://www.tigertint.co.nz/

Corresponding part numbers for the below pic in here: http://opposedforces.com/parts/legacy/en_b12/type_11/exhaust_system/exhaust/illustration_1/ Same again here: http://opposedforces.com/parts/legacy/en_b12/type_11/exhaust_system/exhaust/illustration_2/ Then pics of the individual gaskets/numbers in here, just missing a couple (eg: secondary ECV UP gasket): http://japanesecarimports.net/parts?cat=96&sub=2857&sec=2875&var=51&dc=y

More info in here too: Suitable oils sticky: http://clubsub.org.nz/forum/showthread.php?14056-Suitable-Oils

Go to your local exhaust shop for a new gasket. Im currently using just gasket silicone with no leaks.

BE/BH rails are identical to V5/6. Those would bolt on but looks like they come with threaded hose fittings, so would need your hoses/fittings changed to suit. Plus you'll need an adapter to run your original fuel pressure regulator, or an aftermarket FPR/FP gauge. Money better spent elsewhere IMHO, your OEM fuel rails will outflow your injectors any day. Just polish your originals up while everything's apart:

P2092 is AVCS related. Have you ever pulled out the AVCS solenoid oil feed filters and thrown them away? Could also be a stuck AVCS solenoid from broken filter debris: http://clubsub.org.nz/forum/showthread.php?22885-New-AVCS-Issue-(V7-on)-oil-feed P2092 - OCV Solenoid Valve Signal A Circuit Open (Bank 2).

Or try the air compressor boost leak test:

11.6v is very low, especially during winter. Could just be that it's cranking slowly, also the fuel pump prime might not be getting the pressure high enough with a low voltage prime. Check the battery voltage with the engine idling, should be about 14.4v. Showing the alternator is ok. Then shut the engine down/ignition off and monitor the battery voltage. It will probably show 12.5-12.8v at first, then very slowly drop back to 11.6. Showing your battery is toast. Could also charge the battery over night, or get a jump start in the morning to see if it starts easier.

https://partsouq.com/en/search/search?q=22690AA321

11.6V is low, should be about 12.6V. Is the engine turning over (cranking) but wont fire, or will the engine not turn at all?

Nah, not without loom changes and wiring in an external ignitor. The newer 4 pin coils have the ignitor built in.

Not really, other than swapping it out for a known good one or visually checking for cracks in the coil body. Here's the resistance specs/testing procedure for the older separate ignitor coil packs: http://www.main.experiencetherave.com/subaru_manual_scans/FSM_Scans/coilpacktest.jpg For ignition trouble/misfires pulling leads one at a time identifies which cylinder is playing up. Once the plugs are checked, swapping leads between cylinders to see if the problem cylinder changes can identify a bad lead.

Be worth checking your plugs out. Could also blast the lead head that's covered in oil with brake cleaner to see if it makes a difference, or just pull that lead to see if the idle/miss changes at all. Could be a dirty idle control valve, give it a good clean out with carby cleaner etc. Or a vac leak somewhere. If ether (starting fluid) is sprayed near a vac leak the fluid will be sucked in and the idle will change. Or do a good old boost leak (pressure) test, by blocking the intake off at the AFM: Then pump 10-15psi into the manifold with an air compressor. Any leaks will hiss and be obvious:

Forged versus cast.

As long as nothing is leaking the only negative would be a slight delay in boost gauge response, due to the BOV diaphragm/actuator. Doubt it would ever be noticeable with 2 gauges side by side.

A faulty vent door motor would show up in diagnostics. Be worth checking all of the white plastic vent lever arms out under the dash, make sure none are broken or unclipped. Worst case scenario is a leaking/blocked heater core that's been bypassed to hide a problem. Be worth pulling the TMIC off and checking the heater hoses are connected as they should be. If it wont blow hot or cold but the blower motor will still work wired to the battery, then it will be a dead blower motor resistor.

Try going in from the drivers side, just in front of the intake air control valve (hose #1). Full HVAC diagnostics starting on page 3475 in this workshop manual: http://clubsub.org.nz/forum/showthread.php?39909-Workshop-manual-BE-BH-2003MY-Covers-TT-4442-pages-by-Fuji-Heavy-Industries

Yes it will, just reuse your original sock filter.

Guessing they'll be the same anyway. See if your WRX heads have the ID3 and ED3 valves.

IIRC it's just the exhaust valves that are sodium filled. Guessing the V5/6 WRX does, same as the V5/6 STI and BE/BH TT. The valve faces should have ID3 on the intake valves and ED3 on the exhaust valves: