say i have an ecu that's originally designed to run one pair of injectors. could the wiring to those injectors be branched off of to run a second pair without burning out the injector driver in the ecu? maybe the sum of the impedence of the 4 be the same as the sum of the pair, if that makes sence, to keep from damaging the injector driver?

 

3 days and 17 views, don't tell me i've stumped u all.

 

Yes, potentially. It's totally dependent on the design of the injector driver in the ECU, and how overengineered it was from the factory. I'd be hesitant to do this with an engine I cared about.

Following Ohm's law, the amount of current the ECU would have to sink is determined by the voltage across the resistance (impedance really) of the injectors. So one 3 ohm low-impedance injector is going to draw 4 amps, at 12 volts (because V=IR, thus I=V/R, or 4 = 12/3). Two of those injectors, running in parallel, are going to use 8 amps (because resistors in parallel acheive 1/((1/R1) + (1/R2) ... + (1/Rn)) resistance).

As far as running injectors in series; I'm not sure how good of an idea that is. Two identical injectors run in series having 12 volts dropped across them, will be 'seeing' 6 volts each. This is going to affect the injectors' opening times.

 

interesting. here's a reply from another site i posted the same question on:

"I did that; just make sure that the total impedance is the same, before and after. My original setup had 13 Ohm injectors, and then I used two 3 Ohm injectors and a 7 Ohm resistor. Worked just fine. The computer just needs “to see” 13 Ohm, it doses not matter how many injectors or resistors there are."

 

That means he's running the injectors and resistor in series. He's creating a voltage divider between the injectors/resistor, which means (if I did my math right) he has about 2.6 volts across each fuel injector. I can't imagine that's good for his injector opening times.

 

That's not a very smart thing to do...

If the injector driver needed a 13-ohm minimum impedence, then I can see you getting away with it, but as a7r has already mentioned...

With multiple injectors on one injector driver, you run the risk of having one or both injectors not being able to open.
It's a matter of current.
Current being limited by how robust the injector driver is.

Please don't be messing around with the stock ECU's trying to do this...


-Ted

 

this isn't a stock ecu. i was curious if it was possible to use a 4bbl throttle body(4 injectors)with one of those holley projection setups made for the 2bbl throttle bodys(2 injectors)