I'll assume you have cleaned all the related terminals (cylinder head, inner wing,) and also have cleaned up the terminals on the battery positive terminal distribution board and all the engine bay fuses.
I'd also check the terminals of the relay plate in front of the battery. Clean all of the above as necessary. It may be worth swapping the fuel injection (ECU) relay with the fuel pump relay. Sometimes the contacts in the relays can wear/oxidise and not carry sufficient current at a high enough voltage. You can test the high current switched positive output with a multimeter and ensure it is within 0.25 volts of battery voltage (ideally with engine running so it is drawing current).
I expect the fault to lie somewhere in what I described.
Failing that, if you disconnect the multiplug for an injector and the start the engine, you should have the MCSF log a P020*/P120* code pertaining to the relevant injector. You could disconnect the plug for no.2 injector to ensure the fault code is indeed for no.2 injector. That would tell you that the connection is good and the multiplug is fitted to the correct injector. It won't tell you if the spray pattern and delivery volume for the injector is good but it should be as you stated the injectors were serviced. It should verify that the fault lies elsewhere and also verify that the wiring from ECU to all injectors and back to ECU is good.
That then takes you back to my original point of power supply or a defective injector. You could verify the injector is good by disconnecting the ignition coil and running the engine from cold for a few seconds. If the spark plug is removed, it should be wet with fuel but in any case, I'd expect a pre-cat O2 sensor fault to be triggered as the mixture would be so far out.
Another possibility is that there is an issue with a multiplug terminal for no.2 ignition coil. Unfortunately you did not give the fault code so this is only conjecture. If so, I'd expect 2 fault codes; 1 for the misfire and another for a no.2 coil circuit fault. If you have a 4.8mm male spade terminal, you could insert it into each of the no.2 ignition coil terminals to check the female spring terminals are tight enough and give a good connection.
As already stated, the erratic fuel gauge suggests it is a main positive or earth fault though.
Last edited by Fruity; 4 Weeks Ago at 11:03.