Lane A Light Steady - Injector Error

"Can someone explain to me why ECU didn't report this event as Ignition Coil failure, instead of Injector failure?"

Let me play the Devil's Advocate here.

The ECU Reports an Injector Failure.
It is found that the Plug Caps have a problem.
The Plug Caps are repaired.
Under certain power settings. the Fuel Injector fault returns. 

Is this a case of Confirmation Bias?
The Plug Caps had a problem that might have been causing RF Electrical Noise, but Not any ignition failure.
Nothing to detect.

An injector draws a current that is out of the normally expected value and is reported as a fault.
Because a Plug Cap was found to be faulty,  This Confirms that the Injector was not the problem. (???)

Is it possible that there are two unrelated issues at play?
The Plug Caps were burned but caused no detectable problem (yet!)
The Fuel Injector has a problem that has not been identified.

The ECU can only report what it can detect at the far end of the circuit.
The ECU intermittently sees an improper current in the injector circuit and reports it.
Note the term "Injector Circuit".
It could be the actual Injector, a connector, the wiring, a fuse connection, or anything else in the circuit.
All of these items are in series and appear as a single fault to the ECU.

If the ECU is reporting an Injector Fault, it would be false logic to assume the Plug Cap is the real cause.

Re:  Confirmation Bias

Bill,

Thanks as usual for your comments. We are still struggling to identify the cause and the aircraft is still grounded. I have tried to obtain a loan ECU to eliminate that component, but at ~€10,000 I am not going to buy one, plus they are on 14-16 weeks lead time. I have measured the electrical resistance of the Fuel Injectors, they all measure 11.4 ohms. Although they could break down at high rpm / vibration. I also agree that it could be multiple faults or a red herring with the ECU / BUDS reporting. I have cleaned and checked the ‘Fuse Box’ Connectors, Fuses, Relays etc. 

The iS Engines aren’t really fit for purpose from a fault finding view. They are pushing the 915iS engines in the UK which worries me because they still have the same Electronics. The mechanical bits seem robust enough its the electonics that let them down.

Regards

Malc

Why are you trying to obtain a new ecu and do not try first changing injectors. A resistance test with a multimeter is only a weak proxy of a real dynamic test . At around us$200 for a spare injector  it worth trying.

Anything is worth trying, its just I have been there before buying very expensive Rotax parts to find it doesn’t cure the problem.  The annoying thing is Rotax know the causes of these problems but don’t disseminate the information, which in Aviation is dangerous….