4AGE Injectors not Pulsing

[ThePotatoSmasher]

Hi guys, not normally one to make a thread but I'm at a loss.

I have a KE70 with a 16v Bigport (redtop) 4AGE and cannot get it to run. I have a good spark. Power at the injectors, fuel pressure at the rail, but the injectors are not pulsing. Checked earths and they all appear to be good. I've used a test LED in the injector plug (positive from battery, led grounding through injector plug) which when the key is off the LED is on, acc position the LED is on, On position the LED is off and in the start position has a extremely faint flicker. Did the same test with a multimeter and there is almost no voltage when starting. Any idea's what is going on? Thanks in advance.

[oldcorollas]

if LED is on when key is off, the injector is open when key is off?

check voltage between +ve feed to injector plug and battery neg, for off, Acc and Ign positions.

you need +12 to injector plug when on and start, but NOT for off or Acc.

if that checks out, then it's issue with ECU grounding the injectors, which could be any number of things

[ThePotatoSmasher]

if LED is on when key is off, the injector is open when key is off?

check voltage between +ve feed to injector plug and battery neg, for off, Acc and Ign positions.

you need +12 to injector plug when on and start, but NOT for off or Acc.

if that checks out, then it's issue with ECU grounding the injectors, which could be any number of things

I have +12 to both pins on the injector plug in the on and start positions. All grounds are good. I've established the ECU is not grounding the injectors but I cannot figure out why, I have tried a spare ECU as well.

[Javal]

You should not have 12v to BOTH pins on an injector plug at ON/STA, only on one pin. The other one gets a pulsed ground from the ECU.

[jondee86]

You should not have 12v to BOTH pins on an injector plug at ON/STA, only on one pin. The other one gets a pulsed ground from the ECU.

Just to be clear, what Javal says is correct if you have ALL FOUR injector clips disconnected from the injectors. If you only take one clip off and test, because the ECU side wiring from the injectors is common to at least two injectors, you will find 12V on both pins.

Also note that the injectors are pulled to ground internally by the ECU, and the ECU side wiring from the injectors should not be grounded to the chassis. If you ground the injector wires to the chassi, the injectors will be open any time the ignition is ON.

Cheers... jondee86

[ThePotatoSmasher]

Just to be clear, what Javal says is correct if you have ALL FOUR injector clips disconnected from the injectors. If you only take one clip off and test, because the ECU side wiring from the injectors is common to at least two injectors, you will find 12V on both pins.

Also note that the injectors are pulled to ground internally by the ECU, and the ECU side wiring from the injectors should not be grounded to the chassis. If you ground the injector wires to the chassi, the injectors will be open any time the ignition is ON.

Cheers... jondee86

I think that could be my problem. I currently have the ECU grounded to the chassis, and the intake manifold grounded to the chassis. I don't see how this could be a problem? Thanks guys for your help, not normally one to have a winge without having a go.

[dumbass]

make sure your injkectors are not stuck shut
pulse the injectors with battery power
12v to one terminal and touch ground on and off on the other terminal until u get all of them clicking

then put it back to std and try start the engine on aerostart
see if it tries to sort of run ok on aerostart

these 4ags can be a pain sometimes if they don't start straight away
if fuel pump is stuffed or u have no fuel pressure the ecu realises engine hasn't started and sometimes turns of injectors
ive seen this afew times
so make sure u have fuel coming out of return pipe onr fuel rail back to tank
make sure all injectors are free

and one last thing is on some 4ag ecus there is an injector feedback wire
normally white colour
this needs to be connected

diagnosing is fun and not something u learn overnight hehe

[ThePotatoSmasher]

make sure your injkectors are not stuck shut
pulse the injectors with battery power
12v to one terminal and touch ground on and off on the other terminal until u get all of them clicking

then put it back to std and try start the engine on aerostart
see if it tries to sort of run ok on aerostart

these 4ags can be a pain sometimes if they don't start straight away
if fuel pump is stuffed or u have no fuel pressure the ecu realises engine hasn't started and sometimes turns of injectors
ive seen this afew times
so make sure u have fuel coming out of return pipe onr fuel rail back to tank
make sure all injectors are free

and one last thing is on some 4ag ecus there is an injector feedback wire
normally white colour
this needs to be connected

diagnosing is fun and not something u learn overnight hehe

I can pulse the injectors manually. It will run on starter fluid. Fuel pump is brand new, I have pressure at the rail and can hear it draining back to the tank. Injector feedback wire? I assume your talking about the BF pin? Generally what do people connect it to? At the moment I have it connected to the power supply for the injectors.

It's seriously got me stuffed, I can't figure it out.

[dumbass]

yer u have wired right

I would need to look at it to see why
are u near north nsw

[ThePotatoSmasher]

The only think I'm not sure about is how I have the ECU earthed, I have it earthed to the chassis and the intake manifold earthed to the chassis. I hVe heard this is wrong? Unfortunately I am down the south coast.

[jondee86]

The ECU does not earth through the outer case. It has several (usually 3 IIRC) brown earth wires that all attach to a single brass ring connector which is clamped to the intake manifold at the rear of the head by one of the bolts that holds the plastic wiring duct for the injector wiring. Easy one to miss if you have had the head off. If that ring connector is loose/not bolted bown, you will have engine running problems.

Cheers... jondee86

[dumbass]

the engine loom is earthed on the inlet manifold by a small eyelet with brown wires or white/black wires

ecu case does not need to be earthed

I would also get a noid light to test injectors as led test lights are abit funny when testing pulsing things


if u cant figure it out in afew months u can always send it to me and I can go over it and bench test it

[ThePotatoSmasher]

Is using a multimeter an acceptable way to check for pulse. Pretty sure I don't have pulse because I have tested with the injectors externally and no fuel dribbles out. Yet when I pulse them manually with the battery they pulse just fine.