Megasquirt Injector Settings

[Joel]

Can anyone confirm that standard zetec injectors (Bosch 0280 155 820) are HIGH impedence? I need to set up Megasquirt accordingly and don't want to fry them, as explained below...

 

..."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 PWM time to a number like 25.4, in essence you are disabling the PWM mode. This allows full voltage to the injectors throughout the pulse width.

 

For low-impedance injectors (less than 3 Ohms), you need to limit the current to avoid overheating 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.

 

High impedance injectors can run on 12 Volts without problems. Low-impedance injectors require some form of current limiting...."

 

Cheers.

[Guest Alan_builder]

Can anyone confirm that standard zetec injectors (Bosch 0280 155 820) are HIGH impedence? I need to set up Megasquirt accordingly and don't want to fry them, as explained below...

 

Cheers.

 

Hi mine are 14.5 ohms and I thought the middle digits were 144 not 155 if they are 144 I will get back to morrow.

 

 

I have a host of questions, most of which relate to what GGs you are expecting. I think the standard Zetec things do 157BHP tops on standard pressure. I have some SABB ones for a bit extra without needing to up the fuel rail pressure..

 

 

[Guest old_timbo]

Can anyone confirm that standard zetec injectors (Bosch 0280 155 820) are HIGH impedence? I need to set up Megasquirt accordingly and don't want to fry them, as explained below...

 

..."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 PWM time to a number like 25.4, in essence you are disabling the PWM mode. This allows full voltage to the injectors throughout the pulse width.

 

For low-impedance injectors (less than 3 Ohms), you need to limit the current to avoid overheating 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.

 

High impedance injectors can run on 12 Volts without problems. Low-impedance injectors require some form of current limiting...."

 

Cheers.

 

They are 14.5 ohms so high impedance. High impedance makes life much easier with MS.

[Longboarder]

Argh! Redundancy. I'll get my coat cards!

 

Nigel

[Guest Alan_builder]

Argh! Redundancy. I'll get my coat cards!

 

Nigel

 

Don't worry Nigel, senility set in with me between the garage and the study, I was sure those numbers in the middle of the part number were 144 but they are 155! I would rather be redundant than senile but I think I am both.

 

PS Joel, how have you dressed that Zetec

 

Alan

 

 

 

[Joel]

Thanks all, that does indeed make life easier.

 

Alan, I'm injecting a pinto using Honda CBR (600 RR I think?) throttle bodies. I'd be happy with around 130bhp, slightly disgruntled with less than 120 and amazed if it's more than 140, but in any case the injectors should be up to the job. I have an adjustable pressure regulator so there's a little room for adjustment, but the main aim is refined and reliable rather than raucous and racy.