Hi there, I would like to know some experiences on the driving of VVT solenoid used for variable intake camshaft timing. My situation is, I have a 1994 960 with 2001 S80 3.0 engine, the ECU and all electrical stuff is original from 960.
There is a VVT valve on the intake camshaft. Currently I am not driving it, and the engine pulls nice on the high RPM side, but the low end torque is bad, which is typical for unpowered (or faulty) intake solenoid. I have no OBD codes stored (of course, the Motronic doesn't know about the VVT), and other than the lack of low end torque everything works fine.
There was already some discussion here and on swedespeed, about the PWM frequencies used for controlling the solenoid, welding the solenoid solid, etc...but non of the solutions was good enough (PWM regulation requires closed loop system, welding it solid results in cams with short duration).
From reading the topics, I think I have only two options, and I would like to discuss them and mainly hear some real experiences if there are some.
1) buddy from Sweden told me, one way pretty often used in their country is to use the exhaust VVT solenoid from T6 (exhaust solenoid has more narrow range - only 30° of the cam, compared to the 50° of the intake solenoid which is too much), mount it on the place of the intake one, and drive it (only full ON/full OFF) via some RPM switch. The PWM aftermarket system (VVTuner PRO etc) manufacturers alreadz confirmed me that their systems are not usable for my application, these are for Mazda's which are controlled differently..
2) convert the solid lifter head to the hydraulic lifter head, swap in the 960 solid timing cam instead of the VVT cam, remove the solenoid and block the oil passages, and deal with the different timing gear (make some adapter). But I heard that hydro lifter heads have smaller base circle, so it is probably not just about swapping lifters.
Putting a 960 head is not a route for me, as I have already redone the intake and a lot of stuff (water system, power steering, etc) and I also don't want the 960 intake octopus under the hood.
Also, I thought about putting in a S80 ECU that knows how to drive the VVT, but unfortunately even the first S80's are using CAN bus communication protocol.
What do you think guys?