VEMS on a Subaru Impreza Engine
I have a lot of spare Subaru parts. It would be silly to not make the most of them, so I am about to start experiemnting.
Triggering Options
It would be nicest to use the existing Subaru trigger system, however it works in a strange way... The crank and cam signals must be considered together to derive crank position.
[Details - link to other Subaru Pages]
While I have a think about how to do the Subaru trigger, an acquaintance has made a 36-1 tooth crank trigger wheel that is a direct replacement for the Subaru one. It was originally for his Pectel ECU, but it'll work just as nicely for VEMS. It will even allow me to reuse the standard Subaru VR crank sensor.
The cam sensor signal can either be ignored or the wheel modified to give a single pulse per rotation.
[Large!] Pic of wheel - note that it includes the cambelt cog too.
Injectors
Standard injectors on my old engine are side feed 380cc LowZ.
This type is rare more expensive than top feed HighZ, so may well be replaced by something more standard in the future...
My new Subaru has side feed 440cc lowZ, but with a different fitting into the fuel rail.
Coils
Coils are a passive COP system on the old engine and a wasted spark coilpack on the newer car. Either way, the amplifier unit is external to the ECU, so may be removed in favour of the internal IGBTs in VEMS.
Airflow meter
Will be removed at the earliest conveneince as it is redundant
MAP sensor
Standard old Subaru MAP sensor is good for 1.1 bar of boost. New Subaru is good for approx 2 bar. Both have 3 wires - GND, +5 and signal.
I am re-using a VEMS unit with internal MAP fitted, I'd like to use it as-is. The ECU will most likely be located in the engine bay on this installation, so no problem with pipe lengths & accel enrich.
Is there a high boost internal sensor option for VEMS?
MembersPage/PhatBob Yes 400kpa, but I always go for external ones because the packaging is better and you dont have to plumb a very important and easily damaged/obstructed line to the ECU