Z_WAAAAAZ

‘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

240_to_miata

iTrader: (2)

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

Ted75zcar

iTrader: (2)

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.

Z_WAAAAAZ

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

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