Ignition question for motorheads

[99yam40]

Rod I believe this was just a motor model # he threw out there but I could be wrong.

What does control the OHVs cams and how?
I under stand some other type motors used oil pressure, but does this one use electrical actuators run by ECU or something else?
Just curious.

[boscoe99]

Rod I believe this was just a motor model # he threw out there but I could be wrong.

What does control the OHVs cams and how?
I under stand some other type motors used oil pressure, but does this one use electrical actuators run by ECU or something else?
Just curious.

The valves control flow of engine oil into and out of the variable cam shaft mechanism to advance, retard or maintain the position of the cam shafts with respect to the crank shaft.

[boscoe99]

that engine has a knock sensor and the ign timing is computer con*****ed.
backing the timing down 2 degrees most likely will have no affect.
you can disconnect the cam OCV's and all you will find is it is sluggish at midrange.
at WOT the cams are in full retard same as idle speed.

The knock sensor is doing nothing insofar as the engine is not experiencing any detonation during the test run.

The ECU has been modified so that the ignition timing can be manually changed.

The cam shafts will be where the cam shafts will normally be at wide open throttle, 5500 RPM, in a steady power condition.

All variables on the motor, with the exception of the ignition timing are fixed. Only the ignition timing is being moved to a less advanced position.

On run A the motor is run wide open throttle with 40 degrees advance timing and produces 310 HP. On run B the motor is run with the throttle wide open and the timing is moved to 38 degrees advance timing. And your conclusion is that there will be no change in power. Got it.

[99yam40]

The valves control flow of engine oil into and out of the variable cam shaft mechanism to advance, retard or maintain the position of the cam shafts with respect to the crank shaft.

So is it the ECU that decides what position the cams go to?

Just thought it strange when Rod said WOT and idle, cam setting were the same I guess cam changes while accelerating maybe.

hence the slugish he spoke of

[boscoe99]

So is it the ECU that decides what position the cams go to?

Just thought it strange when Rod said WOT and idle, cam setting were the sameuess cam changes while accelerating maybe

The cams are changing based on a number of inputs that the ECU gets. I have no idea exactly what those inputs are and how the cam shafts react. I don't think cam shaft phase angle is something that can be seen on YDIS.

[rodbolt17]

cam advance and retard can be monitored on YDIS.
shows up in + or - in degrees.
having played with distributor machines setting up mechanical advance curves in years gone by I simply don't think your going to see a big difference on 2*.
on the old high performance mercs it actually had a box that retarded timing by about 5* at or near WOT.

the cams are con*****ed by the ECU based on various inputs,it does it by opening and closing an oil control valve.
there is a filter under the valve that I guess is another mystery filter.

if it sticks in the full cam advance mode it idles terrible.
if it sticks in the full retard mode it is very sluggish in the midrange.