On the way home from work tonight, I noticed that my bike had two "flat spots" in the rev range. The normal one at about 3k and a new one about 5k. I gave it some throttle up a big hill and it sounded... odd. It felt to me like it was only running on one cylinder. Full throttle it felt about as fast as it is in enduro mode, but it was in Touring and done the same behaviors in Urban and Sport too. When I stopped the bike at home and started it up again, the engine spun fairly fast, not the usual dun-dun once a second. I gave it a few revs at the side of the road. It didn't know what to do when the throttle was blipped from idle, it just kinda slowed the revs down and nearly cut out. Then after idling about 10 seconds, I heard the second cylinder come in. The second one adds a really low bass note and it was instantly noticeable when it came on. Engine feels totally normal now. The bike is booked in to Ducati dealer for a visit on Saturday morning as the heated grips are not working. Possibly related? Unlikely. I want to know what it could possibly be, and if the bike will still be safe to use in the meantime? I don't want to risk any damage, but I know the engine has a lock feature if it thinks there's an issue...
How would I test to isolate it to that and see if that's the problem? Would a malfunctioning one exhibit these symptoms?
What was the weather like? Mine doesn't seem very happy when it's cold and damp, which is a bit of a PITA, living in northern England. I don't get noticeable flat spots, more of a spread of lower-than-expected power. Lots of Multistradas will stall if you blip the throttle gently, even when warm.
It was about 0degC outside. It's been running fine every day until now, and the power loss wasn't slight. It was immense - worryingly so. I know the bike won't run as well in certain weather conditions but if this was considered normal, I'd sell the bike tomorrow...
Yes, a faulty MAP sensor would produce similar symptoms. It should show a "PRESSURE" error in the round window of the dash but apparently the error can be present without it showing. The easiest way to isolate the problem is to unplug each sensor one at a time. The ECU will substitute a default value and the engine will run much better. Unfortunately they are virtually impossible to get at without lifting the tank. Check this thread http://ducatiforum.co.uk/threads/pressure-error-on-dash.39277/#post-692200
Found the issue for anyone with similar problems, it was the exhaust valve not returning due to the cable corroding. I took the exhaust off and removed the butterfly valve. Solved.
I must say I'm surprised that a seized exhaust valve could cause the bike to run on one cylinder. Or was it? Perhaps it just seemed to be.
