What is the current state of the 'engine stumble' issue?
#151
Rennlist Member
#152
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I had a stumble that got worse and worse until the engine started going into safe mode, took it to the dealership and it had a bad intake valve. They had her all opened up and showed it to me with the engine running, you could see it flutter instead of sitting at the position commanded by the throttle.
#153
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I had a stumble that got worse and worse until the engine started going into safe mode, took it to the dealership and it had a bad intake valve. They had her all opened up and showed it to me with the engine running, you could see it flutter instead of sitting at the position commanded by the throttle.
#154
Three Wheelin'
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The stumble sounds very much like the same type found on all the new 2015 Ducati Multistrada motorcycles (guess who owns Ducati?). At 2,500 rpm and in second gear, if one jumped on the throttle the motor would hesitate to respond for a few seconds, then it would quickly accelerate. The problem was indeed attributed to the fuel mapping in the bike's ECU which Ducati eventually corrected via a flash/up-map. The difference here is that all bikes of the model year were effected, not just some.
#155
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The stumble sounds very much like the same type found on all the new 2015 Ducati Multistrada motorcycles (guess who owns Ducati?). At 2,500 rpm and in second gear, if one jumped on the throttle the motor would hesitate to respond for a few seconds, then it would quickly accelerate. The problem was indeed attributed to the fuel mapping in the bike's ECU which Ducati eventually corrected via a flash/up-map. The difference here is that all bikes of the model year were effected, not just some.
#156
Three Wheelin'
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it's my thought that the original fueling/mapping would not allow the bikes to pass emissions, because there is no way (absolutely no way) that Ducati intended to release a bike whose motor didn't operate anywhere close to intentions. it didn't operate properly, plain and simple, and very much like what the stumble on the 2014 P-cars.
#157
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I'd say it was worst at around that same point, particularly at low throttle settings, but it wasn't completely normal at other places, for instance in cruise control on the highway it wouldn't be able to hold a speed perfectly, it would kind of surge and waffle. If I stomped on it, it would go though.
#158
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I'd say it was worst at around that same point, particularly at low throttle settings, but it wasn't completely normal at other places, for instance in cruise control on the highway it wouldn't be able to hold a speed perfectly, it would kind of surge and waffle. If I stomped on it, it would go though.
But sadly the lack of error codes continues to be our undoing...
#159
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Hmm my thought is while errors with timing and the like could cause rough or less than optimal operation, a noticeable drop in power is most likely to either be a lack of air or fuel. My first thought was a bad HPFP was the culprit (which they've seen at my dealership too), but it will cause a fault if it's providing less pressure than spec. There's no fault for the throttle butterfly valve loose or in other than the commanded position though, until it gets really bad and the engine senses a lack of power.
#160
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Anybody else at 32c3?
Listening to all the talks about how firmware is software that is crappy, doesn't work right, testing is all blah, updates are random.
They cover not just cars. Trains, train track control systems, heart pacemakers etc etc etc. Everybody here looks at the 911 stumbles and thinks "just another bug... can we finally see the source code. K thnks by".
Listening to all the talks about how firmware is software that is crappy, doesn't work right, testing is all blah, updates are random.
They cover not just cars. Trains, train track control systems, heart pacemakers etc etc etc. Everybody here looks at the 911 stumbles and thinks "just another bug... can we finally see the source code. K thnks by".
#161
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As it stands we have 3 solutions / theories.
1. Faulty intake valve
2. Plenum
3. S/W mapping
The fact that the stumble appears after x,000 miles with no apparent S/W changes or modifications to the engine, would lead one to believe that some component ceased to function properly (such as an intake valve).
PCNA will not touch the car with a barge pole, so what is one to do?
I suppose head over to an Indy for a compression test?
1. Faulty intake valve
2. Plenum
3. S/W mapping
The fact that the stumble appears after x,000 miles with no apparent S/W changes or modifications to the engine, would lead one to believe that some component ceased to function properly (such as an intake valve).
PCNA will not touch the car with a barge pole, so what is one to do?
I suppose head over to an Indy for a compression test?
#163
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I bet Elon Musk could solve the problem in a couple of days.
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#164
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The stumble sounds very much like the same type found on all the new 2015 Ducati Multistrada motorcycles (guess who owns Ducati?). At 2,500 rpm and in second gear, if one jumped on the throttle the motor would hesitate to respond for a few seconds, then it would quickly accelerate. The problem was indeed attributed to the fuel mapping in the bike's ECU which Ducati eventually corrected via a flash/up-map. The difference here is that all bikes of the model year were effected, not just some.
My Aprilia TV4R and RSV4 fueled great. Interestingly though, neither of them seemed like they could be legal from a noise perspective.
#165
Track Day
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Two people in the 991 GT3 forum today reported that they've had this problem and have fixed it by resetting throttle parameters.
Here is the thread in the 991 GT3 forum; note in particular comment number 20, which reports the fix, and comments 23 and 24, which report that the fix was effective:
https://rennlist.com/forums/991-gt3-...st-gear-2.html
Here is the reported fix, which is specified in comment number 9 in this thread:
https://rennlist.com/forums/991/8904...ion-issue.html
Here is the thread in the 991 GT3 forum; note in particular comment number 20, which reports the fix, and comments 23 and 24, which report that the fix was effective:
https://rennlist.com/forums/991-gt3-...st-gear-2.html
Here is the reported fix, which is specified in comment number 9 in this thread:
https://rennlist.com/forums/991/8904...ion-issue.html