E36 M3Evo Vanos control strategy

[Turbo-Brown]

Don't suppose anyone knows what this is do they?

Specifically I'm wondering what type of signal the little solenoids in the unit get from the ECU and under what circumstances. Is it just engine speed related, or load too?

Cheers!

Alex

[kam-325i]

I know load is one, ie: How hard the driver is stompin' on the throttle.

[ian332isport]

Don't suppose anyone knows what this is do they?

Specifically I'm wondering what type of signal the little solenoids in the unit get from the ECU and under what circumstances. Is it just engine speed related, or load too?

Cheers!

Alex

Alex,

I believe the primary signals it monitors are engine speed and throttle angle. It probably looks at others, but those are the main ones.

I don't know exactly what sort of signals are used to drive the solenoids, but suspect it's a simple 12v signal to tell them to open. There's two solenoids for the inlet, and another two for the exhaust. Of these two solenoids (per camshaft), one is used to advance the timing, and the other is used to retard. The ECU will just open and close the relevant solenoid until it see's the cam timing where it want's it. As far as I can tell, the cam timing is fixed when all the solenoids are closed, and only moves when one (or more) of the solenoids are driven open.

Cheers,

Ian.

[Turbo-Brown]

Aah now that is interesting!

I was thinking that the solenoids received a pulsed signal of varying duration to control the cam position.

Presumably the engine management keeps an eye on where the cams are in relation to the crank rather than the system operating open-loop.

Cheers for the input!

Alex.