Wiring problem causing all 4 injectors to not spray?

[garagelu]

I recently bought a non-running s13 with a wiring problem. I bought a brand new engine wiring harness to put it. I wired it up according to frsport.com's wiring guide. When I try to crank the car, all 4 injectors are not spraying.

Here is what I have done so far to diagnose it:

I have an s14 with sr swap and checked some wires on it. There are 4 injector drivers on the ecu pinout. When I probe those 4 wires with a test light, they have ground with ignition off. With ignition, on the ground goes away. On the car I am having problems with, I can probe those 4 injector driver wires, and there is no ground at all.

There are 3 constant injector grounds on the ecu pinout and I checked those with a test light and they are all getting a constant ground.

Also, there is nothing wrong with the injectors. This should be strictly a wiring problem.

[lazysk8er2]

"This guide is for swapping an S13 SR motor into an S13 240SX chassis."

i think putting a redtop into an s14 is a little different.

try this link
http://zilvia.net/f/tech-talk/183376-s13-sr20det-into-s14-chassis-wiring-harness-help-me-out.html#post1916236 (http://zilvia.net/f/183376-s13-sr20det-into-s14-chassis-wiring-harness-help-me-out.html#post1916236)

[garagelu]

The car I'm working on in a s13 sr in s13 chassis. I also own a s13sr in a s14 chassis. This is irrelavant anyway since controlling injector is the same between the two.

[army240]

You should have 12V constant on one of the wire on the injector. The ground is controlled by the ECU, to control the injection time and timing. Get a noid light, an oscilloscope, or at least a multimeter... test lights sucks to diagnose electrical problems!

My opinion is either you don't have your 12V on your injector, or your ECU don't trig all four injector, wish could be cause by a bad CAS. Do you have good spark?

Frank

[cotbu]

The injectors get there power source, from the same wire the ecu's backup power is. If, you have 12v on that wire and 12v at the ecu's backup pin. your injectors should have 12v. Find out where you're missing 12v. Go from there

[garagelu]

I think you guys may be missing the point. I am not having problems with 12v power. I have 12v power to the injector. I am not getting ground on the injector.

So if I clip my test light to a power source and touch the probe to each injector ground wire, I have nothing.

[fcdrifter20]

could be bad ecu. have u tried switching that out with a good working one yet??

[garagelu]

I'll actually be putting the ecu into my friends car to see if it runs tomorrow. At least this will get it out of my mind and narrow it down a little.

But what's baffling me is that when I put the ecu into my s14, it has ground on all 4 injector output wires but when I put it back onto the s13, I have no ground.

I didn't try cranking my s14 with that ecu because it's not stock and didn't want to screw anything up. I just hooked it up to check for ground.

[fcdrifter20]

did the car u got already come prewired??or did u do it yourself? and i would get a dmm if i were u, cant realy rely to mcuh on a test light

[garagelu]

No, if you would read my first post, you will see that I said that I bought a brand new harness and wired it myself according to frsport.com's wiring guide.

And telling me to get a multimeter doesn't help me in any way. You might want to tell me where I should start testing. And yes I do own a multimeter.

I still don't think it will matter. If a test light doesn't light up at all, that means I am not getting voltage. Should read the same thing on a multimeter.

[Z U L8R]

i hear what you're saying. you should never get a constant ground from the ecu to the injector signal wire.

yes you need an ignition power source (red wire) on all 4 injectors. which you've said you are getting power.

the ecu will get the signal of when to fire the injectors from the feedback it gets from the cam angle sensor.

the ecu will only send these ground pulses if the motor's turning over or it thinks the motor's turning over because the cam angle sensor is spinning.

there's nothing inbetween the injector plugs and the ecu as far as this circuit is concerned. so if your injectors are getting power like you say, but they're never getting the ground signal from the ecu then you have 3 possible problems that i would investigate in this order.

1. the ecu is not wired in correctly, it is missing a power or ground, please recheck the wiring and verify that the ecu does have powers and grounds where it should. it is possible that you wired it correctly and simply have a broken wire in the harness. thoroughly double check the wiring.

2. the cam angle sensor is bad, easy check, if you're getting spark on all 4 cylinders then the cam angle sensor is not bad.

3. the ecu is bad, try known good ecu.

those are the only 3 things it could be if everything else is as you say.

best of luck,
Dave

[AWDJosh]

check to see if you have gas?

[garagelu]

i hear what you're saying. you should never get a constant ground from the ecu to the injector signal wire.


Yes this is for sure because if that were the case, the injectors would be spraying all the time.



1. the ecu is not wired in correctly, it is missing a power or ground, please recheck the wiring and verify that the ecu does have powers and grounds where it should. it is possible that you wired it correctly and simply have a broken wire in the harness. thoroughly double check the wiring.

2. the cam angle sensor is bad, easy check, if you're getting spark on all 4 cylinders then the cam angle sensor is not bad.

3. the ecu is bad, try known good ecu.


1) The only things I have done were rewiring the two plugs by the battery tray, the cluster wiring plug, and extended the injector plugs so I could tuck the wiring. Its possible that I broke a wire installing the harness.

2) I am almost 100 percent sure that the CAS is good because I shocked the shit out of myself testing for spark. Probably need to go get a spark plug tester.

3) I'll be installing the current ecu into my friends 240 tomorrow and seeing if it cranks over on his car. I'll post up results tomorrow.

[ReLiC]

Gas hoses might be flipped??

[Z U L8R]

the wiring you did is the wiring that matters.

the two plugs by the battery are where the ecu and all your other powertrain are going to be getting power and are wired into the fuse box. if there's a problem with that then you will be having these problems. if the wiring is incorrect whether it's your bad or you used a bad diagram, things don't work, things get fried, and people get frustrated.

wiring's not rocket science but there is a lot that can go wrong if not done properly.

i can't vouch for the wiring diagram you used because i don't trust other people's diagrams.

from what i can tell you're not a dumb dumb so i hope you figure it all out.

worst case if you still can't figure it out and need me to check your wiring hit me up and i can get right on that.

gl,

Dave

[KoukiMonsta]

the wiring you did is the wiring that matters.

the two plugs by the battery are where the ecu and all your other powertrain are going to be getting power and are wired into the fuse box. if there's a problem with that then you will be having these problems. if the wiring is incorrect whether it's your bad or you used a bad diagram, things don't work, things get fried, and people get frustrated.

wiring's not rocket science but there is a lot that can go wrong if not done properly.

i can't vouch for the wiring diagram you used because i don't trust other people's diagrams.

from what i can tell you're not a dumb dumb so i hope you figure it all out.

worst case if you still can't figure it out and need me to check your wiring hit me up and i can get right on that.

gl,

Dave

I love when zilvia is legit:kiss:

but putting your ecu in a friends car (as you are doing) will rule out the bad ecu. but i am with dave quadrouple check the wiring that you did just in case.

[garagelu]

check to see if you have gas?

Gas hoses might be flipped??

Wow, I feel insulted by these posts. Do you guys really think I am that ignorant and stupid?

Yea these may be simple mistakes and I will admit that I make simple mistakes but no gas and flipped gas hoses.....come on. I already said this is strictly a wiring problem.

[garagelu]

I love when zilvia is legit:kiss:

but putting your ecu in a friends car (as you are doing) will rule out the bad ecu. but i am with dave quadrouple check the wiring that you did just in case.

Yea legit posts are great. Stupid posts like above are a waste of time.

So maybe I am just stubborn but I just don't want to think its the ecu and this is why.....

The inexperienced previous owner of this car brought the car to a local shop that specialized in z cars to get a diagnosis on the car.

I talked to the owner of the shop to see what he found. He basically said that they did get the car running but only if they held the wiring harness in a certain position. So he ruled that it was a bad wiring harness. So if the car was running as it sat, the ecu should be good.

But oh well, I am going to spend the minute or two to swap ecu's and rule out the ecu.

[garagelu]

Ok just got back home from swapping the ecu in my friend's car. Installed the ecu and the car fired right up so its definitely not the ecu.

Does anyone know if there is a relay or something connected to the wiring for the injectors?

[Z U L8R]

doh >_<

well, could be worse, you could have a bad ecu lol

there's no relay for the injectors. they get power, then the ecu gives them the ground they need to pulse.

Dave

[garagelu]

doh >_<

well, could be worse, you could have a bad ecu lol

there's no relay for the injectors. they get power, then the ecu gives them the ground they need to pulse.

Dave


Honestly I would rather have had a bad ecu than deal with the wiring harness.

I've had some interesting encounters with wiring. Last year my car started hesitating every once in a while and then got worse and my car would start bucking back and forth. Long story short.....pulled the whole harness and traced the injector wiring to find a corroded and broken injector power wire.

Thanks Dave for all the help. I'll be contacting you for hands-on help if I can't figure this out.

[cotbu]

If, your ecu was fried; you would have at least 2 problems to deal with. This is a good way to fry an ecu:So if I clip my test light to a power source and touch the probe to each injector ground wire, I have nothing.

Back probing to ground for a 12v test is OK, but if using a test light, 5v will make the light turn on and ultimately cause a false positive, for 12volts. You should be using a MM or turn you test light into a continuity tester and test all of the associated wires.
You could also disconnect the coil packs harness and remove the CAS and spin it. that's only really needed if you're sure that you have a good ecu and good wiring.

P.S. I know you have help locally, I just think that you can figure this out on your own. G/L

[army240]

Back probing to ground for a 12v test is OK, but if using a test light, 5v will make the light turn on and ultimately cause a false positive, for 12volts. You should be using a MM or turn you test light into a continuity tester and test all of the associated wires.
You could also disconnect the coil packs harness and remove the CAS and spin it. that's only really needed if you're sure that you have a good ecu and good wiring.


This is exactly why I told this guy to use something else than a test light.

If you ECU is good, just take the time to check the wiring... Yeah, it can be a pain to do, but eh, it's pretty costless! Do it step by step. Check the continuity between wire at ECU an INJ(there's not a big chance that all 4 wires are open, but, it would rule out at least that!)­.

Also, you can check your relay, power to the ECU, grounds, sparks, etc...

BTW, I don't think you're a retarded, but when you ask for help, be ready that people will brainstorm and throw some wierd idea at you, covering the basics too.