Injector signal wires have constant weak ground

[xgrapher]

I was facing some strange issues with my brand new M84 and after looking at every single configuration I thought of checking the wires physically. When probed the test light on the injector 12v side it tested ok with the ignition ON. When checking the signal line on all the injectors with all of them plugged out, I found a very weak light glowing on the tester when I crank the engine insteak of it doing on - off - on - off it does on - weak - on - weak. I actually wanted to check the voltage so I used the voltmeter and it was reading 12v.

My problem is that the engine is idling at 11~12 afr and if I reduce the number it doesn't fall gradually. After dropping a couple of numbers it suddenly goes from very rich to very lean. For example from 24 to 21 no difference then from 20 to 19.5 the afr jumps down from 11 to 17 and kills the engine.

I changed everything in the fuel section but nothing makes a difference.

I'm now sure that it is this weak current that is causing the injectors to remain partially open. Should my test light glow even a little when key on engine off? It doesn't on other ecus but don't know about Motec. Please explain thanks.

[David Ferguson]

What injectors are you using? Are they low-impedance (Peak and Hold), or high-impedance (Saturation drive)?

Are you sure all the injectors are working? When idling, what happens if you disconnect one injector (try this for each injector) -- does the engine run rougher, or is there no change?

Can you provide more air at idle by adjusting the throttle stop (or IAC valve), then bringing the engine speed down with reduced timing?

[xgrapher]

They are ID 1000 injector dynamics high impedance 12 ohms to be precise. All cylinders are functional when I checked by pulling out coil by coil. I'll check pulling out the injectors one by one tomorrow. Should I try some peak and hold on them?

Idling is high enough around 2k and it responds to timing. Everything is perfect except that it either stays too rich or too lean.

[AdamW]

I dont know much about injector drive circuits but it is common for transistor type circuits to have small current leakage so this sounds normal to me. Your fueling problem is related to your setup which I have commented on in your other post.