Yes is an ME ecu. And to open loop aint an option on there is "closed or switched as only option" which is why im looking at basically a open loop setup run in closed loop mode..
as for your comment to oil pressure and oil temp variation of change.. fair comment and agreed I realise to without the cam sensor the system would be primitive in its accuracy which is why all later vvt's had that so could have larger more snap response of change within there vvt.
im aware to its function like this would be of very basic at best in doing this but to some form of transition effect with a slight veriation within the transitional reaction time in relation to temp i cant see would be that bad, rather than run no transitional effect at all I would have thought having some would be better? 🤔 (i have taken account for this and is why over load my veration of pwm and thus degrees is very little, and on the other axis is very gradual in its transition of slope progression over the higher rpm.)
It isn't like its seeing the major transition of oil viscosity or pressure from cold to hot engine change being its got to be upto temp anyways before running. Any incorrection towards afr through that slight change of cam veriational speed change will be picked up in the wideband trim anyways and im not running boost or high compression pistons so i wouldn't think it to be risk of det on the timing graph changing of anything dramatically in the shift of change.
For behaviour If anything as the engine got hotter the vvt rate of transitional change would become faster and sooner. So as I apply load it would go to full on advance sooner (same as if it was just on but with still abit of transitional effect feeding in there) and as it hit higher rpm it would raise hp and drop torque off abit more quickly when hot as be transitioning a fraction faster to turning the vvt down but would still have of transitional effect rather then just nothing.
So yeah my print out on dyno be slightly more torque favourable above 5k on first pull and alittle more hp favorable above 5k afew pulls later on dyno but wouldn't think would be really measurable within drivability over what you would get from the transitional benifits on the power within drivability is my thinking 🤔..
I maybe still wrong but felt to be worth ago.
TLDR; Honetly mate its your car so have fun doing whatever you are going to do, my solid advice is to just run ON/OFF because oil viscosity and pressure changes far more than I think you appreciate
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I think the variation you are going to end up with is going to be MUCH greater than you appreciate. And yes oil viscosity changes a bunch with temperature, and oil temperature on the dyno will not be the same as on the road by a decent margin. The only way to run this open loop would be to have a correction table for oil temperature and oil pressure which would both require sensors and still wouldn't work nearly as well as a position sensor (which is why they did it for OEM).
Speak to whoever is mapping it and get their take on it. But from my own experience you want as much consistency as possible, anything inconsistent from the moment it was mapped means the tune has changed. While fuelling doesn't matter so much because a shift from an AFR of 14.5 to 14 likely doesn't matter, its also very easy to catch and sort with a lambda run in closed loop mode.
You can try this yourself by turning off closed loop idle and seeing how often you are at your target idle speed - it will be never btw. and the cam advance will drift far more than idle because its position is directly related to oil pressure. I suspect what you will find is 50% duty will sometimes be (lets say) cam fully advanced and other times see the cam hardly advance at all. Furthermore the solenoid has not been designed for PWM so you will have to workout what frequency it is happiest running at all whilst having no idea if the cam has even moved.
If I were mapping this I would ignore everything you are doing right now and just set it up as ON/OFF and do the runs to determine switch over point.... there really isn't enough time to be faffing about chasing inconsistencies during a dyno session unless its development work - or if your tuner has already done the ground work and can categorically state this will work well (already has tables to chuck at it).
This is also why whenever we did a turbo car we would either use closed loop boost control or an external spring/ball regulator - its a nightmare having 10psi of boost one run and 14 another. At the end of the run you set an overboost threshold (to protect the engine from divvys) and a week later you have a customer back in moaning the car is spluttering on boost all the time - because suddenly the open loop PWM value you set is not hitting the same target it was on the dyno and instead hits boost cut intermittently.
