Injector Impedance Questions ATTN: Ivan/Peter(parrot)/Banpei

[CHACAMAN]

gon Wrote:

shanemck Wrote:I was told if they are less than 8ohms they are low impedance, is this for the megasquirt? If so i'm havin the same prob.

you are right.
megasquirt does work with low imp injectors.
there are two options for this , either you use pulse width modulation



or you can use an adaptor board
http://www.aeu86.org/viewtopic/tutorial-...e29/t/7516

check the "final notes" on the first post.

I highly recommend the second option, several problems have been reported with using pulse width modulation.

I am using one of these adapter boards without a glich so far.

But remember If you are using a MS 3.0 this have the Fly back board installed the old version of the MegaSquirt need a additional Injector
Board

The MegaSquirt 3.0 can Drive Hig or low Injector only setting the PWM

For Example:

If you are running high-impedance injectors (greater than 10 Ohms), then set the:

* PWM Time Threshold to 25.4 msec, and the
* PWM Current Limit (%) to 100%.

# In essence you are disabling the PWM mode. This allows full voltage to the injectors throughout the pulse widths.
# For low-impedance injectors (less than 3 Ohms), you need to limit the current to avoid over heating the injectors. To do this, there is a period of time that you apply full battery voltage [peak] current, then switch over to a lower current-averaged [hold] current, i.e. peak and hold. Alternatively, you can add resistors in series with the injectors. See the Injectors and Fuel Supply section of this manual for more details.

To run low-impedance injectors with the PWM current limit mode, you need to set two parameters - the "PWM Current Limit (%)" and the "PWM Time Threshold (ms)" - both are on the “Constants” page. The current limit % is the percent duty cycle when the current limit is invoked. The time threshold is the amount of time from when the injector is first opened until the current limit is activated.

1. Start with:
* PWM Time Threshold = 1.0 millisecond, and
* PWM Current Limit (%) =
o 30% on a V3 or V3.57 main board (if you have the active flyback circuit installed).
o 30% on a V2.2 main board (if you have the separate flyback board installed).
o 75% on a V2.2 main board (if you do not have the separate flyback board installed).


http://www.megamanual.com/ms2/tune.htm#pwm

i have a 4AG 16V Running Evo Injector 570CC without resistor pack
only the MegaSquirt is driving the injectors