3b s2 coupe resurrection

[newsh]

Check the chips are plugged into the ECU properly?

[andy10v]

I think we are chasing our tail a bit!
Basically we know the injectors are not being grounded by the ecu for some reason. I would check the continuity back to the inlet manifold ring. Then continuity back from the inlet to the ecu. If thats all intact then check the ground pins mentioned above for continuity with a good chassis ground. Then that leaves either the connector or the ecu!
Might have some input tomorrow if I can find that spare loom!

Ok, will check the injectors back to ecu plug tomorrow.

ECU ground for injectors and ecu grounds have continuity to intake manifold.

[andy10v]

Check the chips are plugged into the ECU properly?

Nope

Will check tomorrow.

[twoqu]

The injector ground is from pin 14 to the inlet manifold so that needs extra special attention. I would also check for continuity between all those ground rings and a chassis earth rather than just continuity back to the ecu, particularly the inj one!
Charge the battery.
Clear the faults codes. Crank it and see what comes up in the 02 field again.
If the hall sensor faults comes up then we need to look at that as well. If its a hall sender issue then the injectors won't fire. Doesen't explain the output test issue though to my mind as the ecu must ground the injectors to make them click.

[andy10v]

I checked and got continuity for

14/55-Ground for Fuel Injectors (N30-83)
10/55- One of the Grounds for the ECU
19/55- Ground from the ECU for various ECU controlled devices
24/55- Power Ground for "actuators" other than injectors

Between the ECU loom plug and the intake manifold

[twoqu]

Not sure I am explaining it too well. By checking continuity from the ring back to the ecu does not prove it is grounded only that the connection is intact. Really the engine is poorly grounded to the chassis. So what I was suggesting is ensuring that the ecu grounds on the inlet are grounded to the chassis. So you should get continuity between the ecu grounds on the inlet and a good chasiss ground in the engine bay if you see what I mean.

[andy10v]

Ah, got you now.

I will check that tomorrow, I have run an extra ground strap from the IM to the chassis when I put the engine back in last year.

[twoqu]

Right not sure if any of this helps but...
Essentially the motronic loom has 5 earths/grounds. Only 4, the ones that go to the inlet manifold end up back at the ecu connector. The fifth which is a larger one goes to the A pillar. This appears to be connected to the after run pump and relay and not the ecu as such even though it is in the engine bay/Motronic loom.
So that leaves us with the 4 which go to Pins 10, 14, 19 & 24.
Pins 10 & 19 are on one ring terminal and Pins 14 & 24 are on the other. There is continuity between the shared pins which is to be expected as they share the same ring terminal!
In the wiring diagram its states that Pins 10 & 14 are connected at 17 earth point on inlet manifold. Pin 19 is connected to 138 earth connection (control unit) in Motronic wiring loom. Pin 24 to 84 earth connection engine block front right wiring loom. Which is a bit odd as we know that we know they are paired together!
This leads us to the ecu itself. It seems that various pins are interconnected in the ecu itself which helps to explain the grounds for the various sensor that terminate in Pins 30 and indeed 48. Pins 14, 19, 24, 30 & 48 all have continuity between each other. Pin 10 appears to have a connection but has a measurable resistance, at least on the ecu I probed!
So Pin 30 and Pin 48 would be grounded only if the ecu is fitted I think through the internal connection to one or more of the other grounds.
It does highlight that the ecu is entirely dependent on the engine for its grounding so the engine to chassis grounding is an important consideration!

[andy10v]

That is great info, thank you for taking the time to do that, I will double check continuity back to chassis.

I should be able to check ECU plug-chassis earth ring in footwell.

I will check the ecu matches your one.

I will hopefully get back at it tomorrow.

[twoqu]

As I tried to explain above, the large brown ground cable that goes to the A pillar has nothing to do with the grounding for the ecu or its sensors, despite being in the loom! It is for the after run pump and relay as far as I can tell. It does not go back to any pin on the ecu connector.
If you need any info on the loom, let me know as its far easier to examine off the car than on, especially single handed.

[Error404]

I think what Andy means is using the post on the pillar to test continuity for the injector earths, through the chassis

[twoqu]

Ah! Good idea!
It does mean that the after run pump earth connection is a good candidate for ground in the engine bay!

[andy10v]

I think what Andy means is using the post on the pillar to test continuity for the injector earths, through the chassis

[andy10v]

A spare ABY ECU arrived today courtesy of Alex, still no start.

No fault codes except G28 engine speed sensor.

Output tests all work except injectors, no noise from them.

Coolant temp and IAT are at -49 in measuring blocks.

Span it with the MAF unplugged, pulled out plugs and they are wet and stink of fuel!

[twoqu]

So we are now looking at sparks!
Wonder if you have somehow interchanged the two sensors connectors. Doubt whether that would stop it starting.
Start with power to the coils.