On Sat, 07 Jan 2006 18:41:35 GMT, user@email.address.here (User)
wrote:

>Yeah, I know it's some sort of variable valve timing. But exactly
>what is it as implemented in my 2006 Civic LX? I've done a lot of
>searching on the web, but I can't find my answers.
>
>When does it activate?

Generally above a certain rpm which might vary slightly depending on
load - computer decides.

> Is it a smooth, continuous action, or is it a
>step change in configuration at some engine speed?

You won't be able to detect the transition. At most a slight change
in engine sound.

> Is it somehow
>changing the fulcrums of the rocker arms?

no.

> Is it rotating cam lobes on
>the cam shafts?

no

> Is it rotating the cam shaft relative to the pully
>driven by the timing belt?

no

> Is it selecing different cam lobes?

yes

> Is it a change of the valve lift?

yes

>Opening only? Closing only?

An entirely different cam profile is engaged. How that actually
varies the valve operation may be different from model to model.

> Is its activation a function of engine speed only, or load, throttle
>position, airflow, etc.?

Not sure of all the factors, but primarily rpm.

>Is it done with solenoids in the head, or is
>oil pressure used?

Solenoids (I think) redirect oil pressure which drives a pin to lock
cam followers together. When locked, the valves follow the profile of
the most aggressive cam which, at other times, is unconnected to the
valves.


>
>Any pointers to detailed engineering descriptions would be greatly
>appreciated.
>
>Thanks.