Unresponsive throttle

This was a weird one. I was planning to do a short tide yesterday with a friend. Met in a parking lot, fired up the bikes and hopped onto the highway. Everything seemed normal until I cracked the throttle open intending to leave all the cars behind. Nothing happened, the bike just continued on cruising as if I'd not provided any input. Didn't seem to matter which gear I was in, I could crack the throttle wide open with no real acceleration. Closing the throttle still produced the expected deceleration and engine braking however. I got off the highway and tried switching riding modes but the problem persisted. I shut the bike off and restarted it and everything was working fine again.

Given the bike is just back form it's 9k service I'm slightly concerned that an update to the ECU might be to blame. That said this has only occurred once, the bike rode fine when I picked it up Saturday and I spent an hour roosting around the city including letting the bike sit for 15 minutes at a cafe, the behavior never reoccured. I'll take it to the shop when they open Tuesday, but I'm wondering if anyone has run across this. I know there was an issue with the throttle on some bikes but mine is a 2015 so I don't think that is the case here. Definitely disconcerting to crack open the throttle and not have anything happen.

appliance821 said:

TCU - you're going in and out of limp mode.

Click to expand...

I was wondering if that was limp mode. I didn't see a check engine light and the engine was running quite smoothly. After I restarted it the bike ran fine the rest of the morning and pulled as expected when I cracked the throttle open. It'll be curious to see what the shop says given that it was just in for service.

Now that I think about it, this probably also is why the bike will stumble when cruising around 85 - 90mph. I'll just going along and it'll drop down to 80 as if I closed the throttle slightly and then jump back up to speed. Hopefully it doesn't take much to get them to replace it.

The 80 - 90 thing is weird, but only seems to happen on occasion, it's also possible it's something else like the evap canister causing problems or something. I guess I was expecting limp mode to feel more like limping :-D I'll be calling the dealership to get an appointment today. Not being able to get out of my own way on the highway isn't my idea of a good time.

gatdammit said:

Was it bogging when you went over certain throttle percentage?

Seeing how you had your 9K, I'll throw this out: I pinched my main fuel line when I reinstalled my tank after 9K/ RB work. Bike would run fine until a certain RPM/ throttle percentage, but it would dramatically bog at that point because it wasn't getting enough fuel. You can get a flash light in the trellis at the pivot point in the frame and check for kinks. Mine was a dramatic kink but yours may be less so.

Good luck.

Click to expand...

It didn't feel like it was bogging down, it was strange. I'd be cruising at 85 - 90 in 6th just maintaining a pace. Obviously a bump here and there could cause subtle changes in speed but what I'd feel was almost as if I closed the throttle briefly, the bike would slow about 5 - 10mph and then pick it back up a moment or two later (maybe it was trying to drop into limp mode for a moment and then recovering?). If I dropped below 85 it wouldn't really be noticeable. Could be that above 85 I make a very good sail and any loss in power would be more noticeable. Could be nothing to do with the TCU but I'd be happy if it was resolved.

gatdammit said:

Resetting the TPS was common on the early models. I was told "magnetic anomalies" can affect it's function in rare circumstances. Do you ride with motor magnets in your gloves?

Click to expand...

I don't, and I haven't gone near the mystery spot or any other gravity hills in the western US either.

According to the shop they found that the battery terminals were loose, tightened those, flogged it for a bit and didn't see any further issues. TPS and TCU are both fine. I rode it to work this morning with no issues, so, I'll keep an eye on it but with any luck it was just flaky power screwing things up.

Took the bike out for a spirited 200 miles on Saturday and didn't have any issues despite multiple stops and a lunch break. Got back to SF and ran an errand on the way home and the bike started up in limp mode after sitting for maybe 15 minutes. I killed and restarted it at the next intersection and limp mode was gone. Weird. Maybe still a battery issue? I've been interested in a Li-Ion battery anyway, so I may try replacing the battery to see if things clear up.

dragoontwo said:

Did they check your throttle control unit against the service bulletin that Ducati put out quite a while ago?

Click to expand...

They checked and found no outstanding service bulletins as far as I know. Bike is a 2015 so I think it was produced after that issue was found.

Cdnpuck said:

I had this issue on my 2014 where it would randomly go into limp mode. Turn it off and restart and was fine. Brought it in and they replaced the throttle control under warranty and it never happened again.

Click to expand...

Good to know, I guess I'll keep reporting the issue until I get them to give me a new TCU.