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Discussion Starter · #1 ·
Hello, I need some advise with my engine dieing issue while driving.

I experienced engine dieings while driving. It happened two times on the same day during my third last ride. I am not 100% sure but I think it happened when I tried to change gears, more specifically when I let go of the throttle for a gear changing. Once the engine died, I could not get it started right away. It cranked but didn't start. It seemed that I have to wait for some 20-30 seconds then I can get it restarted maybe a little help with some throttle opening.

There didn't seem to be no problems during my second last ride. Idle was good, no engine dieing, no issue with throttle responses or whatsoever, so I was relieved.

And then it comes to my last ride. I got it started and suddenly the idle fluctuated like a sign graph wave. I increased the RPM to 2.5k-3k and no fluntuation. I let go of the throttle, the engine died. It was all recorded. Please check the first video at the bottom.
I kept recording the symptom. I tried to restart the engine but it didn't start. I waited for few seconds and the with some help of throttle opening I could get it started, and then the idle returned to its normal condition. All recoded in the second video.

I fetched my OBDLINK and scanned with MOTOSCAN but no faulty codes. I went out for an hour of ride to learn the symptoms more and hopping to get a check engine light to get a hint of this issue, but still no faulty codes after the ride.
Here are the symptoms and my thoughts of this issue I learned from the last ride.

SYMPTOMS
  • engine dieing while driving with no prior warnings (didn't happen during the last ride though)
  • engine cannot restart right after engine dieing (although it cranks)
  • rough idle flunctuation like a sign graph wave
  • stumbling with a sudden RPM drop while riding (seems to be occuring while gear changing and/or at low RPM)
  • when it is OK, it is OK. No symptoms of anything.

THOUGHTS
  • I don't think it is fuel problem because I always go to the same gas station. Although when I experienced the symptoms first time (during my third last ride) I refueled at a different gas station but it is visited by a lot of other riders, too, and I didn't hear any complains from others.
  • It is a little different from TPS sensor issue. When the TPS sensor has a problem, the idle fluctuates more randomly and feel that engine is going to die. The engine doesn't die all of a sudden like this issue.
  • It doesn't seem to be the battery either, because when symptoms are gone, the engine starts with no problem. Idle is stable, too.
  • I went through 20,000 km (=12,000 mile) regular inspection last month and rode only 1,600 km (=1,000 mile). The spark plugs changed and ignition coils were healthy by then.
  • I searched online and Crankshaft position sensor error seems to give similar symptoms.
  • My other guesses are oxygen sensor or fuel related components but not fuel.

Any advise is welcomed to narrow the cause. Thank you!

 

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Water in your fuel tank? If you live in an area with fluctuating temps and a relatively high humidity level eventually you will get a bubble of water or moisture in your gas tank. It will float around in there and at times get sucked into the fuel pump and cause the symptoms you describe. It happens more often if your bike sits a lot or has sat a prolonged time between long rides and fill ups.
 

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2018 BMW R nineT
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Hello, I need some advise with my engine dieing issue while driving.

I experienced engine dieings while driving. It happened two times on the same day during my third last ride. I am not 100% sure but I think it happened when I tried to change gears, more specifically when I let go of the throttle for a gear changing. Once the engine died, I could not get it started right away. It cranked but didn't start. It seemed that I have to wait for some 20-30 seconds then I can get it restarted maybe a little help with some throttle opening.

There didn't seem to be no problems during my second last ride. Idle was good, no engine dieing, no issue with throttle responses or whatsoever, so I was relieved.

And then it comes to my last ride. I got it started and suddenly the idle fluctuated like a sign graph wave. I increased the RPM to 2.5k-3k and no fluntuation. I let go of the throttle, the engine died. It was all recorded. Please check the first video at the bottom.
I kept recording the symptom. I tried to restart the engine but it didn't start. I waited for few seconds and the with some help of throttle opening I could get it started, and then the idle returned to its normal condition. All recoded in the second video.

I fetched my OBDLINK and scanned with MOTOSCAN but no faulty codes. I went out for an hour of ride to learn the symptoms more and hopping to get a check engine light to get a hint of this issue, but still no faulty codes after the ride.
Here are the symptoms and my thoughts of this issue I learned from the last ride.

SYMPTOMS
  • engine dieing while driving with no prior warnings (didn't happen during the last ride though)
  • engine cannot restart right after engine dieing (although it cranks)
  • rough idle flunctuation like a sign graph wave
  • stumbling with a sudden RPM drop while riding (seems to be occuring while gear changing and/or at low RPM)
  • when it is OK, it is OK. No symptoms of anything.

THOUGHTS
  • I don't think it is fuel problem because I always go to the same gas station. Although when I experienced the symptoms first time (during my third last ride) I refueled at a different gas station but it is visited by a lot of other riders, too, and I didn't hear any complains from others.
  • It is a little different from TPS sensor issue. When the TPS sensor has a problem, the idle fluctuates more randomly and feel that engine is going to die. The engine doesn't die all of a sudden like this issue.
  • It doesn't seem to be the battery either, because when symptoms are gone, the engine starts with no problem. Idle is stable, too.
  • I went through 20,000 km (=12,000 mile) regular inspection last month and rode only 1,600 km (=1,000 mile). The spark plugs changed and ignition coils were healthy by then.
  • I searched online and Crankshaft position sensor error seems to give similar symptoms.
  • My other guesses are oxygen sensor or fuel related components but not fuel.

Any advise is welcomed to narrow the cause. Thank you!

The rough idle would make me try doing a throttle balance. Another thing, the proper seating of all 4 ignition coils on the spark plugs.
 

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Discussion Starter · #4 ·
Water in your fuel tank? If you live in an area with fluctuating temps and a relatively high humidity level eventually you will get a bubble of water or moisture in your gas tank. It will float around in there and at times get sucked into the fuel pump and cause the symptoms you describe. It happens more often if your bike sits a lot or has sat a prolonged time between long rides and fill ups.
I ride quite often and emptied the tank before the last ride, so the videos were taken with new fresh fuel. Also I keep the bike underground where it feels drier than outside atmosphere. But I will check water in the tank. Thank you.
 

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Discussion Starter · #5 ·
The rough idle would make me try doing a throttle balance. Another thing, the proper seating of all 4 ignition coils on the spark plugs.
Throttle balance done right after the second last ride. There was nothing to adjust so didn't touch anything.
Spark plugs were torqued in during the last inspection about 1,600 km before. If the spark plugs are not properly seated, would the symptoms stay all the time? not necessarily?
 

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Discussion Starter · #8 ·
Can you start with inserted gear and pulled clutch? If not, it's probably the switch there Set of microswitches
A problem when changing gears could be the kickstand switch. Switch, kickstand
Check for cable damage on both of them as well.

btw: did you wash the bike or had a rainy ride? Any water in any plugs?
I can get it started with inserted gear and pulled clutch lever.
I will check kickstand switch.
I wash my bike regularly and rode in rainy days. I will check for wet plugs, too.
Thank you.
 

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I ride quite often and emptied the tank before the last ride, so the videos were taken with new fresh fuel. Also I keep the bike underground where it feels drier than outside atmosphere. But I will check water in the tank. Thank you.
Even when you ride to near empty there is still about 1/4 to 1/2 gallon of liquid in your tank. I chased the same thing on my '14 standard (classic) and finally found a blob of water floating around at the bottom of the gas tank. I fixed it by removing the gas tank and physically drying the inside out with lint free paper towels. I also switched to non ethanol fuel for all the bikes. It's been good as new for the 3 years, not even a stumble.
 

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2018 BMW R nineT
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Throttle balance done right after the second last ride. There was nothing to adjust so didn't touch anything.
Spark plugs were torqued in during the last inspection about 1,600 km before. If the spark plugs are not properly seated, would the symptoms stay all the time? not necessarily?
I meant the coils, not the plugs, ie, the coils properly pushed onto the plugs, particularly the lower ones. Intermittent contact would give you a rough idle and maybe the odd stall.
 

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I don't know the BMW that well yet, but if the TPS is good, water in the fuel checked, coils seated and plugs good the next thing I think I'd look at is throttle body balance

Coils can be problematic to diagnose, they can test fine but act up when called on to produce a spark in the cylinder.

Can the Motoscan look at live data, like the GS-911?

I'm thinking if the TPS isn't good the bike would probably hunt and that could be seen on the live data, perhaps see if triggers to the coils are symetrical on both sides, but it wouldn't diagnose a faulty coil pack (I don't think)

Due to a RapidBike Evo throwing false codes I know that apart from getting a Check Engine, there are also errors which don't throw a Check Engine, but I assume MotoScan would have picked something like that up

That's about all I have with my limited knowledge of the BMWs
 

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Based on the surging idle and hard starting, I’d take a look at the fuel pump/regulator/strainer. Check for any variation in how your fuel pump is sounding…if it’s wearing prematurely, it could fall on its face and pick back up once pressure builds. I’d expect to see a code appear if it were running lean, though. I’m checking my Moto scan now to see what the live data parameters are and will report back
 

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Discussion Starter · #14 ·
Thank you for many inputs. I have been checking things this Saturday you have advised.
First of all, I did not go through the same sympton since I wrote here. I rode 4 times short and long, and my bike is all OK, nothing wrong.
Here is what I checked and did though:
  • water in fuel tank: could not check yet
  • throttle balance: good
  • ignition coils and spark plugs: properly seated and torqued to spec. no wet plugs. Motoscan does not show much but could not find any odd values
  • opening/closing of fuel tank cap: did not make any difference
  • kickstand switch: doesn't seem to have an issue. cable and connector conditions are good
  • water in the air filter: filter was dry, but since I checked it almost like a week after the sympton, I will re-check this one when the sympton come out again
  • fuel pump/regulator/strainer: out of my DIY ability. I will have to have a repair shop to check it when I need to go to one next time. Although I heard the same sound everytime I turn the key on.

One mechanic advised me of TPS issue. One condition that was the same when I experienced the symptons were that it was rainy day. I though there was a possibility of TPS getting water inside, so I disassembled TPS and check the condition of carbon track, O-ring, rubber packing, and so on. All seemed OK but rubber packing seemed to be a little weak so I pasted assembly grease on it carefully hoping it will prevent water sneak in if any. Also check the resistance value and there was no sudden surge.

Now I will have to wait and see if the symptons appear again whether dry or rainy.
 
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