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Duratec and Microsquirt: can I reverse injectors?
Kghaas - 29/3/13 at 11:33 PM

Hi
I am doing my first microsquirt harness, and have a quick question:
Can I change the + for the - on the injectors? This would realy save me a lot of cutting and soldering.
Usualy I would have done it, since the injector just is a normal magnetic valve, but the reason I am asking is that the injector is marked with an +

Any input appreciated.

Regards
Knut

The injector:


PS:
The car which is geting a new powerplant
Plan is Duratec 2.0, GSXR750 ITB's, Microsquirt, Flak alu sump.

snapper - 30/3/13 at 05:44 AM

If its marked + then I would feed it + usually +5v but you must check volts and impeadance
Not being funny but why would you reverse polarity and expect it to work!

wylliezx9r - 30/3/13 at 08:46 AM

I would say no. Injectors have a ignition positive and the ecu basically pulses the earth to the injector.

mookaloid - 30/3/13 at 09:00 AM

If I remember my physics at school correctly, the direction of the magnetic attraction depends on the direction of the current flow. So no it won't work if you reverse the polarity, it will probably try to close rather than open.

pjay - 30/3/13 at 09:51 AM

Agree with others, no.

If you're wanting to modify the standard injector loom to reuse the EV6 connectors then you could swap the pins in the connectors themselves - very fiddly but doable. Alternatively, as you say, wire cutting and soldering.

[Edited on 30/3/13 by pjay]

Kghaas - 31/3/13 at 04:24 PM

Tanks guys,

I followed your advice. Only took 10 minutes of extra work.

MikeRJ - 2/4/13 at 01:33 PM

quote:
Originally posted by wylliezx9r
I would say no. Injectors have a ignition positive and the ecu basically pulses the earth to the injector.


quote:
Originally posted by mookaloid
If I remember my physics at school correctly, the direction of the magnetic attraction depends on the direction of the current flow. So no it won't work if you reverse the polarity, it will probably try to close rather than open.


Injectors don't have permanent magnets inside, they are basically a magnetic solenoid, so the polarity of the current (and hence the magnetic field) is usually irrelevant. The Bosch injectors with the polarity marking will still work either way around, but from what I have read the opening current is a little lower when used with the marked polarity, which means a slightly reduced opening time.

flak monkey - 2/4/13 at 06:50 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by wylliezx9r
I would say no. Injectors have a ignition positive and the ecu basically pulses the earth to the injector.


quote:
Originally posted by mookaloid
If I remember my physics at school correctly, the direction of the magnetic attraction depends on the direction of the current flow. So no it won't work if you reverse the polarity, it will probably try to close rather than open.


Injectors don't have permanent magnets inside, they are basically a magnetic solenoid, so the polarity of the current (and hence the magnetic field) is usually irrelevant. The Bosch injectors with the polarity marking will still work either way around, but from what I have read the opening current is a little lower when used with the marked polarity, which means a slightly reduced opening time.


Mike is correct in this case

sebastiaan - 2/4/13 at 08:05 PM

If injectors are polarity marked, they *might* be fitted with supression diodes. If you reverse polarity on those, they will effectively short circuit the injector drivers and burn them out.

That said, I've never come across injectors that have them built-in. Always best to check with a multi-meter though, and if at all possible connect the part as it was intended. It'll make things easier to understand for the next guy to work on the car.