Setting PWM criteria

[OB6D]

Hello,

From the megamanual:

Setting the PWM Criteria

To tune the PWM [pulse width modulation] values for your engine, you need to know what kind of injectors you have: low impedance or high impedance.
If you are running high-impedance injectors (greater than 10 Ohms), then set the.... etc...

For low-impedance injectors (less than 3 Ohms), you need to..... peak and hold...

I understand it this far.
But now my setup, it uses injectors of about 11 Ohm, so i'm using high impedance injectors. But there's two in parallel on each bank of the Microsquirt. That'd make 11/2=5.5 Ohm on a bank right?
Well then i'm still running high impedance injectors... but... heh? And they're not really low either, it's still over 3 Ohms... but... uhmm... i dono...

Do i go the peak and hold way or the other?

And then further down in that same section of the manual it says this:

You may find that you can idle at a very low PWM%, but the engine will stumble or cough if given any throttle. This can be due to a too low PWM% especially if your injectors are large and the idle pulse width is approximately equal to the PWM Time Threshold. In that case you may be idling almost entirely on the PWM Time Threshold. So rev the engine occasionally as you are tuning the PWM parameters, to ensure that you haven't gone too low.

My injectors are large, my idle pulse is 2.5 to 3ms and it does exactly this as described above, so i'm afraid i got this part wrong maybe...

I went the first way, as if they was still high impedance. I've tried the other too, with peak 'n hold, and it still runs the same. It won't let me change things while running though, as suggested in the manual.

[800vtwin]

2.5-3 ms at idle is good. If you have a stumble, look at the accel enrichment.

Yes two 11ohm in parralell would be 5.5. I haven't read that part of the manual but hat is over 3 so set it for high.

[racingmini_mtl]

It's not because it's 5.5, it's because it's 11. You take the value of a single injector even if you put 2 (or more) in parallel. A high impedance needs full battery voltage for the duration of the pulse width and not a peak&hold setup.

Jean

[800vtwin]

It's not because it's 5.5, it's because it's 11. You take the value of a single injector even if you put 2 (or more) in parallel. A high impedance needs full battery voltage for the duration of the pulse width and not a peak&hold setup.

Jean

Good info.

[OB6D]

Thanks Jean. Had the manual been that clear, i'd have gotten it right first time. Thanks again, that's one more error out of the config.