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Hi guys!
My car is running a 2jzgte vvti with bc272 cams and heavy valve springs. I also have oil pressure and temp sensors to monitor oil temp/pressure for more precise cam control. I've been neglecting posting about this issue because I've been stubborn and trying to tune it out on my own. Basically at idle my cam angle will stay at 4 degrees when my target is at 2 and when holding a steady 2500 rpm while driving, the cam target will be at about 5 but but the actual angle will stay at 7. Different rpms will change this. I've adjusted the duty for my cam base duty cycle, and played with my PIDs. Since i have oil pressure and temp I've set my PID control tables to have oil pressure on the y axis and oil temp on the y axis like the picture below, so I can adjust my PIDs at different temps and pressures, but I can't get my can to stay om target. For my base duty cycle I'm only using the x axis with oil temp only, I may add a pressure y axis in the future, but for now it's only temperature. Since I keep going off target and it kills my afrs I built a cam angle correction table for the fuel map, which keeps my afrs on target, but the PID control for the cam is getting annoying. Ive also attached a picture of the cam table for afr correction, it works well with keeping my afrs normal, but I can't get the cam to stay on target. Any help will be appreciated!
Hydraulic VVT is usually disabled at idle due to the highly variable oil pressure. Most OEMs will only activate it above about 1200rpm. So idle position is irrelevant really.
But if you still have excessive offset above say 1500 rpm then it is likely your control terms.
When there is an offset present, what is the duty cycle doing? and how far off the base duty is it?
Cam control usually works best with minimal integral, so use as much proportional as you can get in there without causing oscillation.
That makes sense. That's why I've had so much trouble dialing in the idle PIDs. Low psi oil, plus I'm trying to push that big cam open with the heavy duty springs. I'll need to pull my logs and look at the duty cycle while above 1500 rpm, but I think it's 41