MicroSquirt.com read only forum (Jan.15,2018)

The manual indicated the following:

If you have low impedance injectors (less than 4 Ohms), set the:

PWM Time Threshold to 1.0 msec, and
PWM Current Limit to 75% (30% if you have installed the 'Flyback Board' daughter card).

You will tune these after getting the engine running. See “Setting the PWM Criteria” in this section. Failure to perform these steps can result in damage to your injectors.

I'm using low-Z injectors (Rover SD1 3.5 liter system) I have retained the OEM injector resistor pack. It was my understanding (iffy at best) that the resistors protected both the MS and the injectors.

Do the above requirements for PWM still hold as a start point? Why?

Thanks in advance.

Jack

Jack,

If you are using resistors to limit the current to the injectors (many OEMs do this) then you treat the injectors as if they were high-impedance.

So if your total resistance (injector+resistor) is about 6 ohms or greater, set the PWM% to 100%, and the time threshold to 25.4 msec.

Lance.

Lance,

Thats' what I thought, but given the magnitude of the downside, toasted components, I'm glad I asked.

Thanks again,

Jack

Jack,

Yeah, absolutely - injectors aren't cheap, and it'd be a shame to fry some!

Lance.