939 Rough running, wont rev/accelerate

boredus · Sep 19, 2021

Evening all,
I bought a 939 Hyperstrada in April this year, it's a 2016 and I got it with about 2300miles on the clock. Usual on/off lean fuelling as standard makes for a shitty ride. I hated it so much I was considering returning the bike to the dealer and asking for a refund.
As I cant find a bike like it - size, engine power, seat height, panniers etc I decided to persevere.
1. Changed map to Sport, instead of Urban - this single handily made the most difference to riding the bike.
2. GPR end can added, exhaust valve left open, fitted an exhaust valve eliminator plug.
3. Couldnt get a Ducati corsa air box lid so I ended up replicating the MWR airbox mod.
4. Fitted a Rapid Bike Evo.

All in all I was loving the bike, it felt like the bike it should have been from the shop.

Sadly that was all short lived and 2 weekends back we went off on a 1000mile tour, we did 800miles and then I gave up. Had to call a rescue truck - flatbed to bring me and the bike home.
Loaded with top box and panniers, she was heavy and it felt like the Hypermotard race map I loaded on the Evo was very rich. The bike had a bit of a flat spot just around 5500 and getting through to 6500 was a bit rough, but it was manageable.
I was getting 100miles to the reserve light coming on, fuelling up it took 10.5 litres. Gradually over the 4 days of riding, this got less and less and the bike would refuse to rev out past 5500/5800 RPM. As soon as I opened the throttle the engine would bog down, loads of black smoke coming out.
It got worse, to the point I couldnt maintain speed going up hill. If I dropped it 3 gears, pulled the clutch in an revved it through to 8K and slipped the clutch it would get up to around 85MPH in 5th. Sadly, speeding on national roads etc I couldnt keep that up and as soon as the revs dropped, she was dying again.
At this point, I was hitting reserve in 45 miles. My friend on his cbr1000rr was using 4L and my strada was using 12L for 45mile.

All in all, I have done around 1300 miles, so now at 3500miles total on the bike. Having spent the Covid tax to buy it, I am currently not wanting to rush it back to Ducati to troubleshoot.

Anyway, I was hoping it was something as simple as a dodgy o2 sensor, but I dont have any CELs or other errors on the dash.

Here is a screenshot from the Rapid Bike software, Can any of you RapidBike users tell me if these are normal readings at 5500rpm? If it isnt the O2 sensors, has anyone else had a similar issue?
It feels like the bike drops on to 1 cylinder approaching 5K rpm.

Could it be a dodgy spark plug causing this?

Regards
Ian

boredus · Sep 19, 2021

Since I got it home, I have set up Kuksol08's Cil1/Cil2 maps. No more puffs of black smoke/soot but there is still a rev wall at just over 5K. I swear it drops on to 1 cylinder and bucks like a wild horse.

Araitim · Sep 19, 2021

boredus said:
Since I got it home, I have set up Kuksol08's Cil1/Cil2 maps. No more puffs of black smoke/soot but there is still a rev wall at just over 5K. I swear it drops on to 1 cylinder and bucks like a wild horse.

Is this while accelerating ,accelerating hard or just maintaining speed? I have chased a stutter with my bike for the past couple years between 4 and 5k rpm. As long as I'm not on that window it's all great. A first guess (pretty much all you can get from a forum) is that the clutch lever switch is going bad. The bike might think the clutch is pulled in and it let you rev it out. That's just an initial guess.

boredus · Sep 20, 2021

Gradual acceleration it gently pushes the wall, stutters and gets 'stuck' at the revs, eventually clearing 6500. After that it pops and bangs and starts to lose power. Would have to clutch it up to 8K for it to hold.

5K open throttle hard and it stutters, bucks back and forth like I am head banging in a mosh pit. Closing throttle, then opening again smooths it out temporarily, then the stutter starts again. Bike sounds like crap at this point.

Drop down to 3500-4K all is well again.

It's worse when the engine is under load - Ie accelerating while driving the bike, with panniers and top box the bike loses speed. Pull clutch in and rev to 8K ok. Roll on power under load, big no way

boredus · Sep 20, 2021

I am going to unplug the o2 sensors after work tonight and go for a ride to see if the O2 sensors are causing it

boredus · Sep 20, 2021

And as if by magic, unplugging the O2 sensors has the bike running quite well. 6th gear, 3k RPM roll on and it picked up just fine all the way through to 9K easy. (Not usual riding behaviour!) But it was an easy and extreme way to test the issues of the last week. 20+ mile ride today was a pleasure.

nickwst4 · Sep 20, 2021

Glad to hear you've made progress in curing what sounded like a very sick bike! Will you replace the O2 sensors, or leave it as it is? You've done quite a lot of mixture modifications so the ECU must be very confused already!

Nick

Araitim · Sep 20, 2021

I seen on the other forum. Good to hear. I seen the one guy showing resistors on a 4 pin square connector. Wonder what that is for, none of the stuff we are working with iuses a 4 pin square configuration.

boredus · Sep 20, 2021

nickwst4 said:
Glad to hear you've made progress in curing what sounded like a very sick bike! Will you replace the O2 sensors, or leave it as it is? You've done quite a lot of mixture modifications so the ECU must be very confused already!

Nick

I will replace them, I have modded the airbox and exhaust so the ECU wont have a good map. Also spent the money on the rapid bike evo.
What is rather shocking is that it is smoother than it has been since I bought it! Just how much do these o2 sensors ruin the engine performance to keep it within acceptable emissions levels.

boredus · Sep 20, 2021

Araitim said:
I seen on the other forum. Good to hear. I seen the one guy showing resistors on a 4 pin square connector. Wonder what that is for, none of the stuff we are working with iuses a 4 pin square configuration.

I'll ask, I dont see how resistors will replace a the sensors as the bike is expecting voltage back?

boredus · Sep 21, 2021

Araitim said:
I seen on the other forum. Good to hear. I seen the one guy showing resistors on a 4 pin square connector. Wonder what that is for, none of the stuff we are working with iuses a 4 pin square configuration.

Tim, see my Ducati.ms post, he has replied about the resistors - placed inline with the bad o2 sensors to try trick the ECU.

Duongtohm939 · Sep 24, 2021

boredus said:
Evening all,
I bought a 939 Hyperstrada in April this year, it's a 2016 and I got it with about 2300miles on the clock. Usual on/off lean fuelling as standard makes for a shitty ride. I hated it so much I was considering returning the bike to the dealer and asking for a refund.
As I cant find a bike like it - size, engine power, seat height, panniers etc I decided to persevere.
1. Changed map to Sport, instead of Urban - this single handily made the most difference to riding the bike.
2. GPR end can added, exhaust valve left open, fitted an exhaust valve eliminator plug.
3. Couldnt get a Ducati corsa air box lid so I ended up replicating the MWR airbox mod.
4. Fitted a Rapid Bike Evo.

All in all I was loving the bike, it felt like the bike it should have been from the shop.

Sadly that was all short lived and 2 weekends back we went off on a 1000mile tour, we did 800miles and then I gave up. Had to call a rescue truck - flatbed to bring me and the bike home.
Loaded with top box and panniers, she was heavy and it felt like the Hypermotard race map I loaded on the Evo was very rich. The bike had a bit of a flat spot just around 5500 and getting through to 6500 was a bit rough, but it was manageable.
I was getting 100miles to the reserve light coming on, fuelling up it took 10.5 litres. Gradually over the 4 days of riding, this got less and less and the bike would refuse to rev out past 5500/5800 RPM. As soon as I opened the throttle the engine would bog down, loads of black smoke coming out.
It got worse, to the point I couldnt maintain speed going up hill. If I dropped it 3 gears, pulled the clutch in an revved it through to 8K and slipped the clutch it would get up to around 85MPH in 5th. Sadly, speeding on national roads etc I couldnt keep that up and as soon as the revs dropped, she was dying again.
At this point, I was hitting reserve in 45 miles. My friend on his cbr1000rr was using 4L and my strada was using 12L for 45mile.

All in all, I have done around 1300 miles, so now at 3500miles total on the bike. Having spent the Covid tax to buy it, I am currently not wanting to rush it back to Ducati to troubleshoot.

Anyway, I was hoping it was something as simple as a dodgy o2 sensor, but I dont have any CELs or other errors on the dash.

Here is a screenshot from the Rapid Bike software, Can any of you RapidBike users tell me if these are normal readings at 5500rpm? If it isnt the O2 sensors, has anyone else had a similar issue?
It feels like the bike drops on to 1 cylinder approaching 5K rpm.

Could it be a dodgy spark plug causing this?

View attachment 4032

Regards
Ian

Omg it is so close to my bike now. I do few mods,change ingition coils,spark plug. Use the rapidbike evo of 939 strada. It have the same flat spot around 5500 to 6500. But after that is ok. My bike also shoot out black smoke reported from my buddy driving behind. Beside that the bike run cooler,more reponsive to thottle. And i hit low fuel light warning after 150km from full tanks.

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gatdammit · Sep 25, 2021

A puff of dark smoke under full chat is OK. Only time I saw excessive smoke turned out to be a cracked rear header, which is more common than we talk about. My smoke was light to medium grey and it will seem like its coming from under the seat.

boredus · Oct 18, 2021

Well, the replacement O2 sensors arrived last week. So I stripped the bike down over the weekend and used the opportunity to install a set of 2018 Aprilia Tuono coils, new spark plugs and the new O2 sensors.
As always, the bike started first time, but idling was a little rough.
The current map installed is KUKs map for the 821. The fuelling was rough and the bike wouldnt accelerate passed the 5500 rpm mark, it was like hitting a wall. Stood in neutral, I tried to rev it up and noticed the rev limiter light comming on at around 7K! something tells me I've cocked that map up. Unplugged both O2 sensors and had a nice ride from their onwards.
Went home and installed the standard Hypermotard map included in the RB software. The bike rides way better but still hits a wall at 5500 and then goes all a bit fuffy/weak on the power. Just doesnt accelerate as hard after 6500 as I expect.
unplug the O2 sensors again on the 3rd ride and again, the bike road much better, albeit not perfect, but so much better.

Now, I am getting an itch to remove the RB and see what happens - so I ordered the RB cancel plug. This should allow me to just swap over without gutting the wiring.

All in all, we are in a way better place than before with the bike not wanting to rev past 5500 / ride at national speeds and guzzling fuel but it's still not right. I realised that if I added the Givi luggage and loaded them up again, with the extra weight I will be in the same place again I think

Araitim · Oct 18, 2021

Usually when these won't rev last 5k ish rpm it's the clutch sensor or the kickstand sensor because it is in protection mode. Unplug one of the leads to the clutch sensor in the lever(the circuit is closed when the lever is pulled and open when it's not pulled in) and see what happens.

boredus · Oct 18, 2021

mmm. it will get there - If I slip the clutch and take revs up to 8K. it just wont roll on to that speed / range from say 4K.
Also, as soon as I unplug the O2 sensors from the RB harness, it all works - yes I get CEL light on the dash but the bike is rideable again

Duongtohm939 · Oct 18, 2021

Araitim said:
Usually when these won't rev last 5k ish rpm it's the clutch sensor or the kickstand sensor because it is in protection mode. Unplug one of the leads to the clutch sensor in the lever(the circuit is closed when the lever is pulled and open when it's not pulled in) and see what happens.

Clutch sensor if it think you in neutral. Will limit you at 8000rpm.

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boredus · Oct 18, 2021

Duongtohm939 said:
Clutch sensor if it think you in neutral. Will limit you at 8000rpm.

Sent from my HD1910 using Tapatalk

ahh understood - thank you

Tim - your comment makes sense now!

gatdammit · Oct 18, 2021

Protection mode will also flash the rev limiter light repeatedly at limit, which I thought was 5500. Only left field thing I can tell you to check for is pinched main fuel line. If you haven't removed the tank, probably not a factor. But I had this and it stumped me for weeks. Basically, when I asked for too much fuel, it bogged and felt like limp mode. It was total based on fuel demand, not really rpm.

boredus · Oct 18, 2021

gatdammit said:
Protection mode will also flash the rev limiter light repeatedly at limit, which I thought was 5500. Only left field thing I can tell you to check for is pinched main fuel line. If you haven't removed the tank, probably not a factor. But I had this and it stumped me for weeks. Basically, when I asked for too much fuel, it bogged and felt like limp mode. It was total based on fuel demand, not really rpm.

This is next on my list, I had the tank completely off, however the original issue was similar performance - lack off - while draining the tank in 45 miles and puffing black smoke.
As soon as I unplug the o2 sensors from the RB evo, the bikes runs OK again.
Will have to keep trying things out

939 Rough running, wont rev/accelerate

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