‘95 Chassis with a 94/95 MS3X ECU and VVT engine swap. VVT running off the Nitrous 1 output (presumably so it doesn’t have to share frequency with the IAC output). PW controlled at 383hz currently.

I got the VVT wired and up and running yesterday. Solenoid clicks, PID settings are just about spot on to hold VVT target, etc etc. Everything works great.

However, when I put the car in VVT test mode, rev the motor up to 3k rpm, and start increasing duty cycle, the only real useable DC is roughly 41-44%. Anything else will either not activate the solenoid or send the intake cam to max advance.

This means I should be running a flyback diode across the circuit to achieve a wider DC range, correct? I did over an hour’s worth of reading on here yesterday and found conflicting reports on needing the diode or not. 2014 and older threads seem to say yes but a few newer threads indicate that a diode shouldn’t be needed.

At any rate, VVT is currently working on the car, I just don’t want to risk frying the circuit.

Thanks as always guys!
-Zak

 

Similar issue with my k swap VVT. Had no idea it might be an issue/risk to the circuit. Following.

 

VVT is not monotonic. It has essentially 3 states, advance, retard, and hold. any DC greater than hold advances to the limit. Any DC lower than hold retards to the limit. Hold is not a static, it is a function of the current angle, oil pressure, oil temperature, and some other stuff.

 

So nothing's wrong, sweet. Always love to hear that.

Thanks for the explanation. Haven't seen that explained anywhere actually.