low impedance injectors, use resistors? - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-22-2010, 12:14 AM   #41
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i have an AEM 10 channel lo-z injector driver box for sale, if that interests you PM me...
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Old 04-22-2010, 10:08 PM   #42
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Quote:
Originally Posted by Joe Perez View Post
Let's say your injectors are 2 ohm, so the total series resistance is 7.5 ohm. Assume 13.5 volts supply, so you'll get 1.8A per injector, total of 3.6A per driver assume you're running two channels.

The current limit on the MS's driver circuits is set at 14A.

You'll live. In fact, the injector performance won't be quite as bad as what the folks running 10Ω have to live with. It'll still make baby Jesus cry, just not as much.
Thank you for your words of wisdom . I guess I won't worry about installing them then.
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Old 04-22-2010, 10:16 PM   #43
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that sucks the resistors wont work for you Cspence, the pack came off Rotornuts car, and he was running low imp. RC550's with a Link ECU.

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Old 04-22-2010, 10:40 PM   #44
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Quote:
Originally Posted by WonTon View Post
that sucks the resistors wont work for you Cspence, the pack came off Rotornuts car, and he was running low imp. RC550's with a Link ECU.

I think they'll work from what Joe Perez was saying. How did he have them wired? Do I just splice a resistor into the 12v source for each injector?
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Old 04-23-2010, 12:09 AM   #45
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yeah! they were wired in right before the ECU in line with the signal wires....
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Old 04-23-2010, 11:40 AM   #46
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Quote:
Originally Posted by Cspence View Post
I think they'll work from what Joe Perez was saying. How did he have them wired? Do I just splice a resistor into the 12v source for each injector?
Hmm. You've got a 1.6, don't you...

Normally, I'd say to splice them into the line between the injector and the ECU. But yours are banked at the INJ harness.

Ideally, you want one resistor per injector. Mostly, this just keeps the heat down. If you run one resistor per two injectors (ie: inline with ECU on a 1.6 harness) you'll have ~ 6.5 ohms series resistance, and be dissipating about 25 watts.

So yeah, it'll be a little messy, but you kinda need to cut apart your INJ harness so you can do this. It doesn't matter whether you put the resistors on the +12 side of the injectors or the ECU side.
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Old 01-28-2012, 11:00 AM   #47
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will the honda resistor box work using a stock ecu? The car runs and drives with stock ecu and original fuel supply. I want to limp this for now untill i get ms, i have 450 injectors yet to be put in. Also have honda resistor boxes sitting around, so if i can use that as a band aid for now id rather not see the car sitting around.
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Old 01-28-2012, 03:49 PM   #48
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Quote:
Originally Posted by hondacivsi View Post
will the honda resistor box work using a stock ecu?
It depends.

You can easily enough measure the resistance across it with an ohm-meter to see what the resistance is. You're looking for something in the general vicinity of 8-12 ohms.

There are some downsides to this.

First, it's my understanding that the Honda box has five wires, with all of the resistors joined at one end to a single common. Thus, the box must be installed between +12 and the injectors, rather than between the injectors and the ECU. Since the +12 supply to the injectors is commoned to a single wire within the INJ harness, you will need to remove the INJ harness from the car and cut it completely apart, bringing out separate +12 feeds for each of the four injectors in order to connect them individually to the box.

Second, running any kind of resistor in series with a low-z injector defeats the purpose of having a lo-z injector in the first place. It removes the ability of the injector to be "slammed on" with a large amount of current at initial opening. I have never done back-to-back measurements, however I would not be at all surprised if a lo-z injector which was so wired exhibited poorer turn-on performance than a hi-z injector of equivalent flow rating.


But the most important factor here is application-specific. If you want to put this box between your stock ECU and some 450cc injectors, then no, that will not work at all. 450cc injectors are way too big to run on the stock ECU.
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Old 01-29-2012, 10:20 AM   #49
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That is exactly what i was looking for. thank you.
Another question, i have tried to look for this. why dont people use more parts from a 323. will the injectors from the gtx do me any justice? Or would i throw parts at this fuel system all day but still need an ecu? Ill be running an internal wastegate at 8psi.
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Old 01-29-2012, 11:09 AM   #50
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as a counterpoint, I should mention that running the JBPerf injector drivers for low impedance injectors works very well except that they take up far too much space in my case and I have a lot of extra wiring and soldering that could fail and cause problems.



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Old 10-09-2013, 01:20 PM   #51
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[QUOTE=DXO;515982]I personally never liked using individual resistors and wanted a cleaner look. I have some friends with lots of Honda parts and I grabbed one of their resistor packs that come on some Hondas. Looks like this:



Wiring is simple too. Here[/QUO

I took the factory wire loom off and none of my wires are the colors in this diagram. I have a 97 with emanage ultimate ecu 440cc injectors trying to upgrade to low impedance 1000cc rc injectors. Will this work for me as well?

Last edited by Eunos93; 10-09-2013 at 01:50 PM.
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Old 10-10-2013, 12:01 AM   #52
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Quote:
Originally Posted by Eunos93 View Post
I took the factory wire loom off and none of my wires are the colors in this diagram.
This is understandable, given that the diagram you linked to is for a Honda Accord rather than a Mazda Miata. Rather interestingly, the color codes for the 1976 VW Beetle and the 2014 Lamborghini Diablo also don't match up.



Quote:
I have a 97 with emanage ultimate ecu 440cc injectors trying to upgrade to low impedance 1000cc rc injectors. Will this work for me as well?
See post #48.

You could make it work by ripping apart the stock injector harness and completely re-wiring it. But it would be less work to splice individual resistors into the wires between the injectors and ECU, and even less work still to run the correct injectors in the first place. Lo-z injectors used to be new hotness, now they're pretty damn antiquated.
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