Ducati diagnosis challenge

The bike: 2014 Ducati hypermotard 821. Completely stock (as far as I can tell).
The issue(s): Runs only on one cyclinder (horizontal).
The facts so far: swapping coils, plugs, injectors, map sensors between the cylinders does not change the issue, ie horizontal cylinder runs, vertical does squat.
Vertical cylinder has compression, power and ground at coil and injector. Fuel line is new.
Dash, ECU, BBS have been sent away and returned tested and or repaired, correct voltage on canbus.
No error message, even while running on one cyclinder.
Occasionally and for no discernable reason, sometimes it will not start at all, cycle key and it will but only on the one cylinder.
There is only one crank sensor and it's good.

It pains me to admit, but this one has me stumped. So, who knows what I've missed?

 

physically check that the plug is sparking and the fuel is being delivered to the second cylinder

 

Check you map sensor!?

 

You've definitely checked all the normal items in terms of 'swapping' components between cylinders to determine if the issue moves. When you remove the spark plug from the vertical after it's been running, does it smell of fuel and feel wet? If the fuel system is working properly and it's only running on the other cylinder, that plug has to be wet and probably fouled.

Have you tried spraying some starter fluid/carb cleaner into the throttles when starting to see if that will get it to fire on both cylinders?

 

Need to look at all your live data.

 

Harness? Verify the coil feed makes it back to the ECU connector?

 

I had an issue on a racebike where I did all the A/B swapping and comparisons. Nothing changed. Then, by accident, one of the connectors to one of the coils broke off. It had fatigued, and the wire broke, but the plastic sheath held it together. Very frustrating, as this had been an intermittent fault.

But, check for spark on the vertical cylinder, check for fuel in the vertical cylinder. If none, I'd say you have a wiring/computer issue, if you have done all the swaps.

 

All excellent replies, thank you.
There appears to be neither spark nor fuel in the vertical cylinder. However the wires and connectors are good and voltage and ground are present where they should be at the coil and injector connectors. Also have continuity back to respective pins at ECU connector. Though I will have another look at both.
The starter fluid idea is an interesting one, haven't tried that yet.
Spark plug is dry. And also doesn't spark. But the ECU has been tested and given a clean bill of health. All injectors, coils, and plugs work in horizontal cylinder.
Sadly, I don't have a tool for looking at liove data, can you suggest one?

I have a feeling it will end up being something really stupid if I ever actually figure it out.

 

Dry cylinder = no fuel injection.
No spark, too.

Check harness for continuity and resistance on the wires between the injector and ECU and Injector and ground. Anything more than about 1/2 an ohm and you have a harness issue.
Also same for the coil (I'm assuming its a coil on cap arrangement).

 

See that's the thing, continuity is good and there is voltage and ground at the connectors for the injector and coil (yes stick coils). Also, both injectors and coils share battery voltage and ground as in the same relay supplies both.

 

It's Italian. Have you tried the Vatican?



Electrical gremlins are, and forever will be, my Nemisis. Interested to hear how this turns out.

 

Find someone with a lab scope. Check signals @ coil and injector, work backward.

 

Check them with a load on them. Also check resistance of the injector coil / spark coil.
Possible weird issues: Bad connection on the connector that will pass voltage but not current (this will look ok when testings, but not actually work in service); coil in injector that is weak, or internally shorted (swap injectors and see if problem moves? - I see you've done this.)

If the ECU isn't throwing errors, it must be thinking that everything is OK. Question: has the ECU been flashed? could there be a problem inside the ECU that is masking the actual issue? Check grounding of the grounds from the ECU as well. At this point, I'd physically inspect the harness looking for bare wire spots, cut/broken wires, etc.

I don't know how experienced you are at electrical troubleshooting. I'd put a meter on the ground lead of the injector and see what it does when the engine is running. It should stay at ground, not jump up each time the injector is fired by the ECU. I'd repeat with the high wire of the injector. It SHOULD be getting pulses from the ECU. Even better if you have an oscilloscope to see the waveforms.
If both are good, have you checked the fuel line to the injector? Is it clogged? You said its new, but verify fuel delivery to injector. Low pressure on the fuel line can act like a non-functioning injector.

 

Looking for a young priest and an old one

 

Swapped both coils and replaced them with known good ones from different bike. No change. Plugs are new NGK.
A connector passing voltage but not current is very interesting. Have to look at that.
ECU has not to my knowledge been flashed and exhuast and intake are stock. ECU was sent out to Carmo for testing and it was returned with no faults found.

 

voltage but no current= resistance. Corrosion, partially broken wire, etc.

Have you tested with a minature bulb? Just be aware of amp limits if circuit is ECU controlled....IE, use correct bulb.

Are the coil and injector both fed by same voltage source? Same ground?

 

I'd focus on the injector until the cylinder starts showing signs of fuel delivery. A spark with no fuel isn't going to do much.

Also - Stuck intake valve? Pull the injector and see if there is fuel in front of the valve? OR even run the injector off the cylinder to see if it spits fuel like it should.

 

Based on another thread here, don’t let a guy with an 80’s Chevy shagmobile work on it…

 

Found the issue.

 

It's a Duc. If there is a stuck valve there some other broken shit under the cover.