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

I'm building my MS II V.3.0 for my porsche 914 2liter. I'll be using stock injectors (low impedence, ~2.4 Ohms i believe), the high current ignition driver and a manifold referenced fuel pressure regulator.

Do I want to wire up the PWM flyback damping circuit? These injectors are rather large for my application and people have had idle problems in the past with older versions of megasquirt because of minimum pulse width restrictions.

Or do I go with resistors in series to limit the current and no PWM? I don't want to stress my board and burn up my progress.

The 1.7L injectors are Bosch p/n 0-280-150-009, the 2.0L injectors are Bosch p/n 0-280-150-019. THANKS!

You can use the stock injectors, though the 2.0 injectors are pretty marginal, as they're so big that getting good idle is difficult. The problem is that with their size, you start to run into practical limits on how short the pulsewidth (the length of time the injector is open) can be. 1.7-1.8ms is pretty close to the lower limit, as the injector takes about 0.8-1.0ms to open fully, and 0.8-1.0ms to close fully. So, at the minimum, you're "open time" is 0, and you're depending on the erratic amount of fuel injected while the injector is opening and closing to supply fuel for idle.

I would say yes, use PWM. However, since you have MS-II you have quite a bit of resolution to play with, so you may not have trouble with min pulse widths, unless you are reffering to the speed of the injectors. Also, your board may not burn, due to current limiting, but get some restors just in case.