retop ECU pin out help, wiring drop resistors

[idahotuner]

why does every single ecu pinout i look at have only 3 injector grounds listed,what is the forth one,getting ready to install my drop resistors and am going to do them near the ecu not in the engine bay. SR20det Wiring Diagram ECU pin out colors (http://www.enginebasics.com/Misc%20Information/sr20det%20wiring%20diagram.html)

Nissan 180SX S13 1991-1996 SR20DET ECU Pinouts | Kouki Tech (http://www.kouki.co.uk/reference/nissan-180sx-s13-1991-1996-sr20det-ecu-pinouts)

check it out for yourself

[idahotuner]

another one http://www.2literturbo.com/files/S13_SR20DET_ECU_Pinout.pdf

[brickerj]

While that is curious, it doesn't matter. All three grounds come together and get grounded on the back on the intake manifold regardless.

You're going to have issues if you try installing the resistors near the ECU because one wire (pin 109) splits off into four which is what powers your injectors. It's much easier to run this one wire into the engine bay, have it split there, and then wire in your resistors there. Otherwise you need to split it by the ECU and then run 4 wires into the engine bay.

The easiest way to do it is to get a resistor pack like what Mitsubishis run. It has 1 wire in and 4 wires out so it does the split for you. All you need is a 5 prong plug and it's that easy.

[VNG704]

Am I missing something or aren't resistors supposed to be in the power wire?

In cabin would leave the resistors away from heat. Have them atleast 6 inches from the ecu. This is what JWT told me. But I'm not necessarily saying in engine bay wouldn't work. Planning to do this soon too.

[idahotuner]

Each injector has an individual ground Going to the Ecu, jwt told me to wire them inti the ground side. Inside the cabin. The ground side is the trigger side. The Ecu completes the ground that is how it controls the injectors. That is a completely different ground on the back of the intake manifold. .
I could put them on the hot side. Coming out of the ecu but not sure how it will affect the injector

[army240]

Pin 109 is the #1 injector driver... Power for the injector (12V) comes directly from the Battery!!!

[GroundPerformance]

Resistor pack are wired to the injector positive side. Here's a diagram before you mess up your ECU.

http://i31.photobucket.com/albums/c390/celicasupraxx/h22swap/resistorpackwiring.gif

[idahotuner]

see i dont have a box, i have the individual resistors from jim wolf, but the pin out for the ecu shows the positive to each injector,so i can wire them into that then. i have wired stuff before and followed diagrams thats not a problem i just wanted the info before i started anything, i wasjust toldto wire the resistors on the ground side.

on a side note i found the trigger wire for the fuel pump relay so i can hard wire both fuel pumps now.

[GroundPerformance]

see i dont have a box, i have the individual resistors from jim wolf, but the pin out for the ecu shows the positive to each injector,so i can wire them into that then. i have wired stuff before and followed diagrams thats not a problem i just wanted the info before i started anything, i wasjust toldto wire the resistors on the ground side.


Those are ground triggers. Positive side of the injector if you trace them are actually just 1 wire that branches to 4. Either way do what you think its right it your car anyway. I've done it this way to many of my setups. I really think you need to do some more research. Following diagrams is one thing understanding what its meant to do is another. ANyways below is how your inline resistors should be wired.

http://img262.imageshack.us/img262/3686/inlineresistors.jpg

[idahotuner]

i have read and googled it to death. i understand the reason for the resistors and the like, it doesnt make sense why there would be 4 injector signal wires and they all go into one then split into 4 again, there has to be a direct wire to each injector from the ecu how else would the ecu control the injectors

[idahotuner]

ok i see the ecu controls it from the ground so the power source can all come from one spot. so i shouldbe able to wire each resistor in line with pin 101 103 110 112 about 6 inches from the ecu

[GroundPerformance]

ok i see the ecu controls it from the ground so the power source can all come from one spot. so i shouldbe able to wire each resistor in line with pin 101 103 110 112 about 6 inches from the ecu

Wrong.... You need to leave the ground triggers alone. Try it if you must.



Here's how you need to do it. Follow the red wires on the top of the engine harness that supplies the positive side of the injectors. Cut all 4 of them and put your inline resistor in the middle. Done.............

http://img25.imageshack.us/img25/8589/dsc00709zs.jpg

[idahotuner]

so those are the wires. thank you, i could track them under the dash, i just dont like the idea of putting them in the engine bay cause i heard the heat isnt good for them.

[GroundPerformance]

so those are the wires. thank you, i could track them under the dash, i just dont like the idea of putting them in the engine bay cause i heard the heat isnt good for them.

Its on the engine bay only not on the dash. Once they're all soldered in place. Just wrap it in Electrical tape with the engine harness and you're good to go. By the time it's done it should just look like the harness has a section that has a bump which is where your resistors are. I'm sure you're using this kind of resistors. I'ts just a resistor There not much heat on where the harness will be at to mess it up.

http://www.jgycustoms.com/specv/images/resis.jpg

[idahotuner]

ok thanks man,those are the exact resistors i have there, guess i will just split my harness open and connect them there

[idahotuner]

got some more questions, the pin 104 is the fuel pump relay i assume this is the signal wire that goes to the relay and trips it so i can splice off of it and run it to my 2 new relays for my fuel pumps?

[brickerj]

Usually with dual fuel pumps you wire them up to switches. This way you can only use one pump for normal driving and then turn on the second pump only when you need it at the track. This also helps you discover a bad fuel pump rather easily by using each one individually. With them always running at the same time you won't know if one is bad until you hit full boost and blow your engine.

[idahotuner]

Yeah. But I am doing an inline fuel pump. And don't want one forcing fuel through the other. One will normally supply enough fuel. I am just doing two for safety.

Decided I am going to cut the power wire at the intank fuel pump and use that wire to trigger my relay for the hardwire going to the pump

[idahotuner]

so these 4 red wires on the left are where i am going to wire in my injector resistors

http://i221.photobucket.com/albums/dd230/idahotuner/2011-10-18115421.jpg

[Traininvain]

So I'm going to bump a super old thread here, because it speaks directly to an issue I've been stuck on for over a year. So I apologize to anyone offended.

I understand that the 4 injectors have a common ignition controlled 12V that is split to them in the harness, and that the actual opening of the injectors is controlled by 4 grounds to the ECU.

When I converted to top feed, I put my resistors in the ground wires, back by the ECU. I did this because it seemed like a better location, and because in my head in made no difference. The overall resistance from +12V to the ECU ground would be the same, whether you put them on the +12V side or ground side of the injector. There can be no argument about that.

So in terms of protecting the ECU from overheating and burning out due to too much current, they accomplish the mission. But is there another reason to put them on the +12V side? It is implied above but I don't understand why.

"Wrong.... You need to leave the ground triggers alone. Try it if you must.

Here's how you need to do it. Follow the red wires on the top of the engine harness that supplies the positive side of the injectors. Cut all 4 of them and put your inline resistor in the middle. Done............."