Thread: using a voltage regulator for the iniectors

I've been reading up more of the battery offset and all the things that go into the calculations needed for properly opening and closing the injectors. Now one problem I had with my old nx was with the 1000cc injectors I would have hunting and idle stabilty issues. To remedy this, even after a professional tune, I increased the idle rpms to around 1100rpm. Its a bandaid in my eyes and would like to come up with a solution to help releave low rpm issue with large injectors. Now I understand that the injector linear to nonlinear flow rate is compensated and calculated through many variables any the one ever changing, unpredictable variable is voltage. And with the voltage issues thatany of us have come across with highly modified cars, it cab play hell on the tune. My idea is to run a voltage regulator set anywhere between 13-14v depending on the integrity of the charging system. Allowing for a much more predictable and constant variable that the ecu can use to calculate proper pulswidth. Now to implement this though the ecu would have to be able to see that the battery offset at the injectors is different from the actually charging system voltage. Would there be any way of setting this up in nismotronic so that the injector calculations are based off the regulated voltage at the injectors vs system voltage?

Thinking about it more, I guess it would be easy enough to change all the battery offset table values to reflect the desired value. Can anyone point out any issues I can run into?

Honestly, the best advice I can give you is to stick to a name brand injector and make sure you are provided the correct dead times and flow rates from the manufacture.

This will make things a lot easier to start from and should only require minor tweaking to get them smoothed out.

Rc injectors are not a name brand injector? Hmm.
So are you saying a regulated voltage would not help at all?

I never said RC wasn't name brand .. but what I did say was to make sure you have the correct injector battery offsets from the manufacturer.

You should be able to find the RC 3ohm battery offset tables floating around to start with, they won't be absolutely perfect but they will at least get you in the ball park.

I have tuned literally hundreds of cars without a voltage regulator on them, but with that being said the injector battery offsets can be tricky to dial in on some injectors (ESPECIALLY LOW IMPEDANCE OLD SCHOOL INJECTORS!!)

In your case, you might not be able to idle and part throttle them much leaner than 13:5 ish without having any hiccups simply due to the injector's characteristics and design.

If you want a better time of things, you would be surprised how much better a newer Bosch body style injector would perform for you during idle/cruise (Injector Dynamics, FID, FIC, etc).

There is currently no way to have a separate voltage monitored just for the injectors.

You know what I did? Let me tell you a lil' background first… Checking on a Blitz display thingy I have. It always puzzled me injector variations with voltage. For example: With absolutely no electrical loads (engine running and everything electric off) I got 1.8-1.9 ms pulse @ 950RPMs (Programed on my chip). If I turn on all electrical loads (Light, wipers, Full blasting A/C, braking, reverse lights, Hazard, Defroster, rolling windows, etc..) I could make the battery voltage drop to 11,9V. Injector pulse at that time was 2.4-2.5ms. That's the way it's supposed to work, injector response time varies with voltage and in order for the ECU to maintain the correct A/F ratio, pulse must be adjusted according to the injector's specifics values.
Then measured with a Voltmeter how much juice the injectors were receiving, and to my surprise, saw a -0.2 (11.7V) voltage loss at the positive wire on the injector harness…. This is what I did.

1.- Fuel pump rewire (Common mod on DSM guys) Used the Audio 4 GA cable to my audio stuff, to power directly from the battery (via a relay) the fuel pump

2.-Injector Harness rewire. Did the same for the positive cable on the injectors (relay). Direct juice from the battery. (Did it for the dist and MAF too).

3.- Hooked a 0.5 Farad capacitor (Audio gear) but directly to the battery, in order to stabilize voltage where the juice flows.

4.- Run a parallel to stock 4GA wire from the alternator to the battery

5.- 9 point Ground kit on specific locations (Close to the electrical paths) Spark pulgs, dist, alternator case, etc, and all the OEM ground points.

6.- MAF ground rewire.

All that work made the car so much smoother, idle inj pulse improved by 0.1ms (Idles @ 1.7ms now) and overall the ECU seems to have less latency to respond to inputs or loads (Radiator fans barely dim the lights now nor drop the rpms as much as they used to when they kick in).
I think doing this on a brand new car it’s totally outrageous. But on a car with 15 years, electrical connections are not as good as before.

I'm an electronic engineer, although I don't work on my field. I'm always trying electrical stuff on my toy.

Oh, and my OCD is what drives all this

Ahh. So my speculations were right. Thank you for this. I like your approach and I had considered the DSM style mod with the injectors. I had ran all this by my professor and he was dumb founded there wasn't a voltage regulator to begin with. Thanks for the reply. BTW, im studying engineering, can I ask why you don't work in your field of study?

Sure, family business is a small Radio station outside of Santiago. Glad I could help