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Injector Wiring

andylaurel

By andylaurel,
in Engines & Forced Induction

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andylaurel Community Regular

andylaurel

Posted
Posted

Ok so i pulled finger this morning at finally got my RB25DE+T finished.

Its got spark, and its got fuel pressure, but the injectors arent opening...

Vital Info -

Car is using a RB25DE (R33) with:

RB20 Loom

RB20 ECU

RB20 CoilPacks

RB25 NA injectors

RB20 AFM

RB25 CAS

RB25 TPS

What i had to do was cut the injector plugs off the RB25 loom and replace the injector plugs in the RB20 loom with the said RB25 items. This was simple, as all the signal wires are the same colour as the RB20 ones, however the common earth is a different (yet constant) colour..

Ok so problem: when i tested with a test light, the common earth on the injector loom will light up the test light when it is earthed on the battery's negative terminal.

Why arent i getting a signal to the injectors?

Is the CAS (which i know controls the injector pulse) not compatible with the RB20 ECU?

The CAS looks identicle, and the plug goes straight on, but the part numbers are different.

:P ,,,, that is me right now.

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BHDave Grand Master

BHDave

Posted
Posted

Because it's a common power, not a common earth? So i'm assuming your injectors have no power maybe?

Except your test light says you have power.

You wouldn't have spark if the cas was the wrong one, though there are some differences between early rb25 and rb20 ones i think you have gotten lucky maybe.

Anyone know if the rb25de injectors are high of low impedance? 20 are high. 25 may be low and popped something. easy enough to measure on the car with a multimeter.

Check that the injector ground wire at the ecu is earthed. Can't find my pinout diagram so can't tell you the pin off the top of my head.

check for error codes

check fuses and wiring back to the ecu, jury rig a positive off the battery directly to the common power wire for the injectors to ensure you have power.

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andylaurel Community Regular

andylaurel

Posted
  • Author
Posted

yeah your right, if the CAS wasnt working, it would not spark!

So that rules that theory out...

The Injector loom is earthed at the two earth points on the upper radiator hose inlet next to the two temp sensors...

The block is earthed out correctly...

ill buy a node light tommorow and have a looksee... man i hate wiring!

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kjb_r33 Experienced

kjb_r33

Posted
Posted
bump

experts needed please

As stated earlier, there is NO common ground for the injectors, thay are fed battery voltage from the EFI relay, the ECU turns the injectors on by grounding them. You should have battery voltage to BOTH sides of the injectors with the key on, engine off. Should be battery voltage all the way to the ECU unless engine is cfranking or running, then it should flash on and off and ecu grounds them./

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andylaurel Community Regular

andylaurel

Posted
  • Author
Posted

ok i understand that now.

1st i will check if the injectors are getting pulsed at the main injector plug, then i will chase it back up the loom from there..

is said injector loom fused? maybe i have blown a fuse?

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Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Man you gotta be serious, I'm having the same problem.. just after I ripped apart my plenum and took out my injectors to be cleaned and flow tested..

now i cant start my car.. just put everything back together like 1 hour ago and nothing.. no injector pulse....

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https://www.sau.com.au/forums/topic/140332-injector-wiring/#findComment-2618998
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James_03 Mentor

James_03

Posted
Posted (edited)

you dont have the injector 12v live hooked up. the negative signal will be pulsing fine from the ecu that doesnt stuff up.

You know what the common wire is on the loom, I thinks its light grey for a rb25 loom, you need to hook this up to a 12v relay and it will start as mentioned.

Dont hook it up to a live without a relay.

Edit: just notices you have a 20 loom, so whatever the constant wire is for that prob wont be light grey.

Edited by James_03
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andylaurel Community Regular

andylaurel

Posted
  • Author
Posted

ok so i've got power to both sides of the injector plugs...

i just dont have a good pulsed earth...

my ECU thinks its controlling RB20 260cc top feed injectors

but its really controlling RB25 260cc side feed injectors...

do i need a resistor pack?

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grim32 Community Regular

grim32

Posted
Posted
ok so i've got power to both sides of the injector plugs...

i just dont have a good pulsed earth...

my ECU thinks its controlling RB20 260cc top feed injectors

but its really controlling RB25 260cc side feed injectors...

do i need a resistor pack?

Grab a multimeter and check the impendence on the rb25 injectors, just put it on ohms and put it on the injector pins.

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