Hi
We have a 2013 Vauxhall Antara 1.4 A14NET in that cuts out and/or sometimes refuses to start. Seems worse when hot but will also do it when cold. It will crank but won't start. It will then sometimes just start without hesitation and run without any problems, sometimes for hours and the next time for no length of time at all. There is no injector actuation and non of the coils are being triggered when it won't start. There is a power and ground supply to the coil pack and there is a power supply to the injectors. There is also fuel pressure. There are no fault codes in any of the modules and you can communicate with the engine ecu when it doesn't start. There is also an engine speed reading in live data when cranking and also temperature sensor and all other live data looks ok I think.

I scoped the cam and crank sensors. The cam sensor signal looks normal but the crank sensor signal looks very strange for a hall sensor but I didn't have a known good one to compare. It just doesn't seem to have the same square look to it like a normal hall sensor. I checked it's 5v supply, ground and 5v reference voltage at the sensor and all are present so decided to change the sensor but the fault remains the same. The signal is the same when it starts and when it doesn’t.

So if the ecu has the correct engine speed signal and cam signals, why is the ecu not firing the coils and injectors? Is the ecu faulty or am I missing something obvious? Maybe I need to check the power and ground supplies to the ecu next and if they’re ok suspect the ECU is faulty.

Scott Neal