Intermittent To No Spark. Multi1200 2016

I’m posting this here rather than in the MultiStrada section as it’s an issue that Im sure is not specific to MultiStradas.

I’ve no photos taken but you all know what coils and HT leads and plugs look like.

I’m racking my brains, have been all day, and am at a loss as to explain or understand what’s going on, or rather what should be happening that isn’t happening.

Maybe I’ve missed something, maybe I’ve made a mistake, it has been very hot today - so hot where I was testing the bike (in his greenhouse) the diagnostic computer threw a wobbly and crashed.

Grab a tea/coffee/beer etc and read on, any and all suggestions welcome.

The bike is a 2016 Multistrada 1200S. The present owner has only had it about 4 months. Apparently it was running absolutely fine albeit he tells me it was a bit tricky to start and the previous owner, who decatted it and fitted a link pipe and baffleless Arrow end pipe ( it’s bloody loud) told the current owner he had to twist and hold the twist grip about halfway when starting the bike. The current owner hasn’t had a Ducati before and just took this at face value and assumed it’s a Ducati thing.

Anyway, he rode it, put it away, all was fine, came to use it the next time and it really struggles to start and when it does it won’t idle and sounds like it’s running on 1 cylinder. He buys 4 new spark plugs and fits them but no change. He searches across the internet, does various things but to no avail. He calls me.

A diagnostic interrogation reveals there’s a misfire on the vertical cylinder. Spark plugs are removed and checked for a spark. The top plug is fine but the side plug is hit and miss as to whether it sparks or not.

Plugs are swapped around, still the side plug doesn’t want to spark but the plug that was there and is now in the top position sparks brilliantly. It’s not a plug that’s at fault.

The diagnostic tool can test the coils, run the test and all 4 pass.

Coils are swapped, the one that was driving the top plug is moved to the side plug and vice versa. Still no spark on the side plug, or just an occasional one, but the original coil for that is now firing the top plug perfectly so it’s not a coil that’s at fault.

HT leads are swapped over, no change and it’s established it’s not an HT lead that’s faulty.

There are 3 wires going to the coil. Brown/White which has 12V from the ECU to it when the bike is turned on, Black which has continuity to earth, and Blue/Grey which has continuity back to the ECU and is the ‘signal’ wire from the ECU which triggers the collapse in the primary coil’s circuit. There are no breaks in the wires from the ECU to the coil or earth - unless in the extreme heat I’ve tested them incorrectly.

The bike is now in the back of the van waiting to be brought out for further testing. However, I’m at a loss as to why there’s no spark. It seems there’s no signal from the ECU which indicates an internal ECU fault but I’m really scoetical that’s the case. I’ll connect the oscilloscope next week and see what, if any on/off signal is coming from the ECU.

In the meantime, any thoughts?

 

What a comprehensive and thorough answer

 

An update: still the same . I checked the connectors to the loom didn’t have either the pins in the coil or the female sockets in the plug pushed back or deformed in anyway - all as they should be.

I connected the oscilloscope and checked it on the signal wire of the V1 coil - the one that fires the top central plug - yes there’s a pulse. However, when connected to the signal wire on the V2 coil - the one that fires the V side plug - nothing. Absolutely sweet FA. I can only deduce the driver for that coil within the ECU is not functioning*.

A bit of head scratching and a lot of research informs me that both coils are triggered together. There are 2 plugs solely to ensure there’s complete combustion within the chamber and the engine, which was running a cat, would not have unburnt fuel going into the cat which would a) damage the cat and b) prevent it passing emissions regs at the time. So, I’m thinking, could I run a piggy back trigger wire from the V1 coil to the V2 coil? This when the ECU triggers the V1 coil the V2 is also triggered. Would that work? Or, is there some reason I haven’t thought of as to why there are 2 separate triggers for the V coils coming from the ECU.

* I’m also suspicious now the reason the previous owner told the current owner, when he bought the bike, you have to hold the twist grip open is because the coil driver in the ECU was slowly breaking down and the spark on V2 was intermittent. Certainly when the current owner started checking things he saw a spark there occasionally and I too have seen it spark once or twice.

Edit : ChatGPT informs me it’s not a good idea to piggy back a trigger to V2 off V1 for a variety of reasons.

 

No, I’ve got a new fully charged battery in the bike which is connected to an external 10A power supply while I’ve been doing my testing so it’s always at 13.2V. I’m confident there’s no issue there but thanks for the suggestion.

 

I’ve just had a fascinating conversation with ChatGPT for the last 30 mins. Im impressed. Too much to copy & paste in here.