Hello guys,

I went Megasquirt 2 and fully followed Aarons writeup. I have only one question regarding injectors that is not fully covered there.

What are the correct settings for PWM Current limit (%) and PWM time treshold (ms) for low impedance stock TII injectors?

In the writeup is 100% and 25.4ms but Aaron says: "The settings presented here are for high impedance injectors. For low impedance injectors, the PWM Current Limit and PWM Time Threshold settings need to be tuned however I have found that because only two injectors per driver circuit are used on the rotary, these settings seem to work fine for both high and low impedance injectors with no damage to the injectors or the Megasquirt."

"seem to work" is not preffered option for me and those values are quite high according to the Megamanual

 

For the record I have never changed the PWM settings on any Megasquirt I or II I have installed on the rotary from the 100% and 25.4. The PWM settings are to limit the current to the bank of injectors. With only 2 injectors per channel, it isn't an issue.

That said, if you want to tune the PWM settings, there are instructions in the manual. About 1/4 of the way down:
http://www.megamanual.com/ms2/configure.htm

There are initial values to set to get the engine running then a link to further refining of the setting. The car does need to be running fairly well to adjust the injector PWM.

 

I had issues with low-impedance injectors and PWM off. I had different issues low-impedance injectors and PWM on.

I'd recommend either adding resistors or changing to high-impedance injectors

 

i dont like to use resistors on the injectors i rather buy peak & hold boards.

 

thanks everyone for the posts but back to the initial question - according to the megamamual I should use Current limit 75% and time treshold 1ms

Anyone using the same settings?

 

I used 75% when running two GSL-SE injectors off of Inj1. Then I burned out the PWM transistor because my setup spent a lot of time near 100% duty cycle.

I am running GSL-SE injectors again after my RC 1000cc injectors died and my I forgot what brand 1200cc injectors turned out to be 880 and 960cc injectors, causing all sorts of drivability and tuning issues! But anyway each injector gets its own driver now and I am running PWM at 30% for now, which is working just fine. When I get some more time, I'll hit it with an amp clamp on my scope and see what the current draw really is, and adjust PWM so that the injectors are drawing 4a peak and 1.5a hold.