is there any type of device out there that will lower the voltage to your injectors? i want to drop it to 10 volts.
the reason is i need to use low impedence injectors. if i do this with a peak and hold , sequential system, with 12 volts or higher it will pull too much current thru the injectors and can burn them up. thanks

 

One side of your injectors goes to 12v and the other terminal goes to the ECM which pulses that wire to ground for a short duration depending on throttle setting, etc. The duty cycle is very low and I don't think there is a problem of harming the injectors or the ECM. Measure the d.c. resistance of the factory coil and the replacement injector coils and compare them. If they are less than half the factory coils, I would consider different injectors or installing a power resistor in each injector wire, but only after determining that the injector works correctly on the lower current due to the resistor.

 

I think the injectors have their rated current at 12Vdc but the question is will your stock ECM sink that much current.

You need to get the current rating on the injectors and find out how much current our ECM can sink. If the ECM won't handle the current you could use power tansistors (or an appropriate power IC) to drive the new injectors.


[Modified by 65Z01, 4:14 AM 8/22/2003]

 

I think the original engine computer for a "peak and hold" injector had a current limiting circuit built into it. I believe the way it works is the initial current is unlimited long enough to pull the pintle the full way; but, after a few microseconds, the current limiting circuit limits the current to just enough to keep the injector "held" in the open position (the idea is it takes more current to quickly move the pintle, but not nearly as much current to hold it open).

Since you are using an ECM that does not have "peak and hold" capability, you could build a circuit to limit the current after a certain amount of time. The problem with this is, if you don't have the information on just how long it takes to pull the pintle full open, you are going to have to do the R & D to find that out before you can build the final circuit. For a batch-fire system, you would need 2 circuits; for a sequential fire system, you would need 8 circuits -- each injector driver would need a circuit attached to modify the current waveform.

A peak-and-hold circuit is designed to quickly move the pintle full open then lower the current to limit the heat built up in the injector windings.

In addition, another thing to keep in mind, injectors that have a lower impedance draw more current and they may draw current that exceeds the design capacity of the wiring and fuses in the existing circuits -- especially, if you don't limit the current after the "peak" time.

Tom Piper


[Modified by Tom Piper, 9:39 AM 8/22/2003]