My money is on an intermittent grounding fault within a coil (most likely a secondary coil), causing the ecu to kill the ignition circuits to prevent damage.
Stalling when revs dropped suddenly
- Thread starter Santa-2512
- Start date
If the engine cuts out when downshifting to 2nd & 1st and you are data logging with the GS911 check the clutch switch operation at that data point.
I had this problem on a previous GS which had an adjustable clutch lever. If the lever went out of adjustment ( the adjuster sometimes caught the hand guard and it would not operate the clutch switch) This would happen.
Ounce the problem was identified it was easy to replicate to prove.
Study the GS911 data, The clutch switch does effect the idle actuators under these conditions.
I had this problem on a previous GS which had an adjustable clutch lever. If the lever went out of adjustment ( the adjuster sometimes caught the hand guard and it would not operate the clutch switch) This would happen.
Ounce the problem was identified it was easy to replicate to prove.
Study the GS911 data, The clutch switch does effect the idle actuators under these conditions.
Bendy toy
Registered user
Mine has aftermarket control levers that don't connect to the clutch lever switch, so the engine will start only when gearbox is in neutral. I really should get it sorted but it's just never been enough of an issue. I had the engine stalling when the primary coils were failing. It was hard to diagnose because they were both going down but still working well enough to run the engine. Replaced (both) primary coils and all was fine again. I still have the original secondaries which look dog rough and probably are not running properly, but the engine runs fine with good fuel consumption. I should also get them replaced but at BMW silly money prices with no obvious benefit, the job isn't happening.
BMW prices take the piss, I fitted a set of secondary BERU coils from M&P advertised as for the 1200GS (the stainless finish ones). It was £159 for the pair (still not cheap) and they weren't quite a perfect fit as the rubber block that meets the underside of the head was at a slightly wrong angle compared to the original coils (requiring a small pinch when tightening the covers), but hey who cares when they work a treat and cure my intermittent coarse running symptoms.
Its only once fitted that you realise how bad it ran on the old coils.
Bendy toy
Registered user
I need to get my secondaries done. I fancy trying a pair of car engine stick coils (three wire type). They'll probably go higher up with HT leads. Used BMW 7 series coils are three wire type for under £10 each so not silly money to try. Research needed of course - dont want to blow the ZFE..
Any way to test if its the coils?
Went for a run today, and it was fine until the last 200 yds comming home, then it had a wobble and it sounded like a misfire !
Couldnt hear to well, plugs and music kept the revs up, and it seemed ok...
Mind you there was some water sitting on the filler cap, so i'm wondering if there's some water in the fuel ??
you have to laugh sometime
Went for a run today, and it was fine until the last 200 yds comming home, then it had a wobble and it sounded like a misfire !
Couldnt hear to well, plugs and music
kept the revs up, and it seemed ok... Mind you there was some water sitting on the filler cap, so i'm wondering if there's some water in the fuel ??
you have to laugh sometime
OK, had a bigger look / play today
No water in filler neck, so that would seem to eliminate the water / fuel scenario
It ran fine for the first 9 miles , but i mad a concious effort to
blip the throttle at junctions, to keep the revs above 1500 ish
No problem, the bike seemed fine --
On the return trip, i rode normaly , and the misfire thing was
back. Oddly enough, it seems to be at 3K as you come onto
open throttle, the engine gives a big cough as if its going to
stall, so you give it some more throttle, and it clears its head
and charges off.
Unsettling if your trying to filter and ride smoothly out of a
roundabout at low gear!
Throttle body balance? plugs / coils or fueling issue?
No water in filler neck, so that would seem to eliminate the water / fuel scenario
It ran fine for the first 9 miles , but i mad a concious effort to
blip the throttle at junctions, to keep the revs above 1500 ish
No problem, the bike seemed fine --
On the return trip, i rode normaly , and the misfire thing was
back. Oddly enough, it seems to be at 3K as you come onto
open throttle, the engine gives a big cough as if its going to
stall, so you give it some more throttle, and it clears its head
and charges off.
Unsettling if your trying to filter and ride smoothly out of a
roundabout at low gear!
Throttle body balance? plugs / coils or fueling issue?
Bendy toy
Registered user
That does sound like a failing coil (or coils). Check the header pipes for temperature when it's warming cold. I spotted mine when water dripped onto the right header and fizzed when it should have really spat itself away. Old primary coils will smell of hot insulation.
Steptoe is your friend ......
intermittent electrical faults are horrible to find .
intermittent electrical faults are horrible to find .
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