Ecu problems I think

[defender dinky]

Hi all,range rover classic 3.5 auto 1989, I've done all the tests in archives efi, problem I have is injectors not opening, tried a noid light but get no flashing, I have power on the white/red wire at sm relay but nothing at fuel pump relay, although I have fuel at the rail and can also flip the flapper and get fuel that way, plenty spark it fires on easy start, injectors not opening, even taken them all off and cleaned them and a back flush, injectors them selves are good, think it could be ecu, but I have two, same thing happening, there's a few connectors missing in my ecu plug is this normal,dd

[Bowie69]

Yes, normal for there to be spaces in ECU plug, they are just generic so used for many applications.

Check your wiring around the AFM and over to the coil, unless the ECU senses a spark through the white/black (I think it is the same on flapper as hotwire) it won't give any fuel, nor turn the fuel pump on again after the initial priming pulse.

From another post, after a quick search: 

The ECU will only fire the injectors if;

1. There are pulses coming from the coil -ve on the WHITE/BLACK wire into the ECU (via the over-run relay, WHITE/BLUE)

2. The airflow meter flap is slightly open (there's a switch in there)

 

(Credit @FridgeFreezer)

The ECUs are very reliable in all honesty, it is quite easy to point the finger at the big misunderstood box of electronics, but honestly, they rarely fail, and the issues are almost always external.

[defender dinky]

I have a continuity test from the w/b wire from the resistor off the coil to pin one and get 6.8ohms which I think is right, is there any way I can check the pulsing, if I put a test bulb on pin one would that show a pulse, and the over run relay clicks, and i also I jumped it, still nothing,dd

[FridgeFreezer]

White/red wire is the starter motor so that's maybe not the most relevant thing to be measuring.

It's possible the flap opening will run the fuel pump even if the ECU is "dead" or not getting power - from the diagram I think it can happen as long as the main relay (13) is powering the brown/orange wire.

There's the weird double-contact relay (13) which is an uncommon type, check that's present and not been swapped for the wrong type. There's also the red "relay" (12) full of bodge diodes to route signals.

You need to check you're got power on the blue/yellow wire (ECU power) and brown/orange wires (injectors etc.)

[defender dinky]

Only got power w/red wire while cranking at sm relay, will check all if it stops raining, i haven't got a w/red wire on starter motor,main brown to battery and a smaller brown to terminal  and a little spade connector to solenoid, thks, dd

[defender dinky]

4 hours ago, defender dinky said:

Only got power w/red wire while cranking at sm relay, will check all if it stops raining, i haven't got a w/red wire on starter motor,main brown to battery and a smaller brown to terminal  and a little spade connector to solenoid, thks, dd

Checked blue/yellow power at ecu plug, brown/orange power at afm checked injector connections in ecu plug all have 11.85v with ignition on, don't think I have pulse on white/black wire, is it the ignition module that creates this pulse via the relucta in the dizzy,dd

[FridgeFreezer]

8 hours ago, defender dinky said:

is it the ignition module that creates this pulse via the relucta in the dizzy,dd

It comes off the coil  -ve terminal via the over-run relay on the shock tower, so a white/blue wire goes through the relay and becomes a white/black wire into the ECU, it's literally triggered from the pulses on the LT side of the coil as it makes sparks.

[defender dinky]

Sorted, although I had spark must have been a weak coil, changed coil started first turn of the key, had really bright light coming from noid light aswell, now for m o t test, dd