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Old 04-14-2023, 07:15 AM   #1
wooshwoosh
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Member#: 514853
Join Date: May 2020
Chapter/Region: International
Vehicle:
2005 GDB-E

Default AVCS discussion - run AVCS without sensors?

Hi all,

While finishing my engine rebuild, I discovered that the AVCS-Camshaft-Position-Sensor holes are missing from my new cylinder heads!

I have a mostly stock version8 EJ207 with single AVCS (intake cam) from an Australian 2005 STi (GDB-E), which is very similiar to the JDM spec C. Running S20 2.0L heads which I did some porting and polishing work on myself along with the original STI valve train (shimless bucket lifters, sodium filled exhaust valves etcetera).

Shock, horror and spilt milk aside I am now seeking your insights, experiences or advice into 'unknown territory' options other than simply sourcing new heads (which is difficult). Current ideas I have include:

1. Drill the missing holes and hope for the best. The hole is 18mm but positional accuracy will likely be off, I am not sure what sort of tolerance exists for this sensor.

2a. Attempt running it as is (crank sensor + front LHS cam sensor only: both LHS and RHS AvcsCamshaftPositionSensors missing and unplugged). and run the factory STi ECU blind, risking a limp only mode and accept the performance hit.

2b. Manually advance my intake cam sprocket gears by 1-3 teeth. What would I be compromising here in terms of high RPM high boost between 4000 and 6400 rpm?

3. Flash and tactrix tune the factory ECU around the issue. I believe that the avcs solenoid Duty cycle is adjustable and that there is a rough translation between crankshaft degrees and camshaft degrees and so it might be possible to run an assumption map that is somewhat conservative and just realised on the crankshaft position sensor along with the left camshaft sensor.



Thank you for your time and consideration and any input that you might offer!
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Last edited by wooshwoosh; 04-14-2023 at 11:40 AM. Reason: added diagram
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Old 04-16-2023, 06:09 PM   #2
subaru_gc8
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2004 WRX wagon
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so right now you have the s20 heads that are not avcs heads, am i correct?
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Old 04-17-2023, 04:05 AM   #3
wooshwoosh
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Quote:
Originally Posted by subaru_gc8 View Post
so right now you have the s20 heads that are not avcs heads, am i correct?
Correct! General casting #:
LHS20 004
RHS20 007

Am currently leaning towards manually advancing intake cam sprocket 2 teeth and leaving all avcs electricals disconnected.

Alternately leaving cam timing stock and just the avcs solenoids connected, not sure if this is safe.
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