no worry, we're all learning here as we go.
I thought cam advance switched on and off with 12 volts
until I checked it with voltmeter, it went on with key on, was on at idle.
and 12 volts stayed there from idle up to 4000 rpm
made me think huh ?? how's this switching.
watch oil pressure gauge. its on 1 at idle, then goes to 3 at high rpm
made me think ah-ha, the varying rising oil pressure is what actually engages it.
the oil pressure engages it as it rises, only way it could work
if 12 volts is there at all times.
I didn't want to free rev it past 4700 rpm to see if it shut off the voltage at high rpm,
to retard the cam timing.
but that's probably how it works. when it gets to 4700 rpm,
the voltage is cut, and it goes back to base timing at high rpm.
my logic, if it cut in/out with the 12 volts at 2100 rpm, the voltage should be zero at idle and with key on, and 12 volts should come in at 2100 rpm. that doesn't happen on my car.
basically the rising oil pressure turns it on at 2100 rpm, and the removal of 12 volts turns it off at 4700 rpm.
the port is always open and 12 volts present from 0 to 4700 rpm.
at least that's what my car does. unless maybe mine is malfunctioning and the 12 volts should not be there at idle. my gut tells me that's how it works though.
i.e. there's not enough oil pressure from idle to 2100 rpm, to advance the cams, by design,
even though the port is open...