R1100RS engine cuts out . . .

[wimblejon]

Hi there,

 

I wonder if any RS/RT owners have had this problem or may have suggestions as to how I can solve this one?

 

I have a 2000 R1100RS - done about 65k miles, not a great deal and I've done most of the servicing myself. The bike's been pretty reliable and hasn't given me much trouble at all, apart from the usual town driving woes like getting through clutch cables and brake pads, too many punctures and the odd mirror scrape.

 

Last October (2015) the bike came to a grinding halt when the engine died on the way home from work. Having had an HES fail for the usual reasons (original component with non heat-proof wiring) and having successfully rebuilt one with aircraft wire, I immediately suspect another failed HES.

 

On the suggestion of a BMW engineer, I replaced the HES with a brand new one (yes, I know, desperate measures!) but unfortunately, the random cut-outs continued.

 

Whilst the bike was off the road I replaced the clutch assembly (it had started slipping when accelerating fast), the crankshaft end oil seals and the transmission input shaft seal. All good, it all went back together well and as usual, the bike stated quickly and a short test drive proved the clutch - except that the engine just died after about 5 mins.

 

No spark.

Pushed it home, removed the tupperware and fiddled.

 

It had a new fuel filter very recently and a replacement coil from Motorworks.

I checked the usual suspects, a fuel pump cycling when ignition switched on and another cycle when the engine is rotated over each TDC, fuel spraying from the injectors when removed and positive LED confirmation of the HES switching alternately left and right when the engine is spun. All good!

 

Tried a start and it fired up!

What had I done? . . . dunno!

 

She was actually running sweet as a nut, having balanced the carbs, very responsive on the throttle and idling well. Ah, I must have fixed the problem so out for another test drive - it failed again after 5 minutes or so, with no spark.

Pushed it home AGAIN!

 

The battery isn't brilliant (but fairly new!) and checking the charging revealed about 14v when the throttle opened to about 2500 to 3000 revs - but when trying to restart after each failure the battery doesn't seem to have a lot of poke.

 

Question: Would a failing battery cut the engine if the voltage drops below a spec'd level? If so, what?

 

Every time I brought the bike back home after a cut-out and then running the battery down trying to start it road-side, I'd put it on charge.

 

Question: will the Motronic (2.2 on the RS) not function unless the voltage is at a minimum? if so what?

 

Question: Could that be why, after attempts at checking wiring looms, component plugs and sockets for corrosion, the bike then started (produced a spark) simply because the battery had reached a critical, minimum voltage?

 

The spark circuit is relatively simple, I know, HES pulsing to the Motronic, sending timed pulses to the coil, creating the spark at the plugs - and it makes me wonder about the Motronic unit.

 

Question: Do they fail?

If so, how?

 

That's the one component I can't really test - other than buying/borrowing a new/reconn'ed one.

 

Question: Do beemer engineers have electrical equipment that can test the Motronic?

I've never come across any mention in any of the forums.

 

HELP! It's driving me nuts!

 

Any ideas/feedback/experience/clues would be VERY welcome and much praise would be heaped on any person/s who assists toward a happy ending :-)

 

Thanks for listening.

 

Jon

[Michaelr11]

I chased this problem with my 2001 RT, and I've been helping a friend fix this on his 65k 96 RT. In both of these, the ignition coil was the final solution.

 

Is there any way you could get a known good ignition coil? Maybe swap yours with a friend with a similar engine/ignition? Until you said you replaced the coil that was going to be my recommendation. Was that a new coil you swapped in? What about the spark plug wires and the plugs?

 

You say there's no spark. This wouldn't effect spark, but if you still have the charcoal canister I would remove it.

 

Please fill in your profile so we know where you're located. There may be a nearby member who can look over your shoulder.

 

[dirtrider]

Morning Jon

 

 

Lots to look at with this one.

 

The very first thing that comes to mind is that your Motronic is failing (or locking out).

 

 

 

Tried a start and it fired up!

What had I done? . . . dunno!---If you cut 12v to the Motronic you might have re-set it????????

 

 

The battery isn't brilliant (but fairly new!) and checking the charging revealed about 14v when the throttle opened to about 2500 to 3000 revs - but when trying to restart after each failure the battery doesn't seem to have a lot of poke.---Very seldom does a battery cause a stall then no start once the bike is started & running good. I have seen maybe two battery issues in my life where a battery had an internal issue & shorted out internally while moving therefore causing an engine shut down, but those instances also wouldn't allow a re-crank until the vehicle sat for an hour or so.

 

Question: Would a failing battery cut the engine if the voltage drops below a spec'd level? If so, what?--- Possible, probably sub 10 volts dc, maybe closer to 9 volts. If I were diagnosing your present problem I would certainly have a voltmeter across the battery while riding to monitor the battery voltage. If nothing found on low battery voltage at engine stall I would then move the voltmeter to the Motronic B+ wire & monitor that, then move the voltmeter probe to the Motronic ignition 12v+ & monitor that (or just use 12v homemade test lights on the Motronic B+ & ign B+ circuits while riding.

 

Every time I brought the bike back home after a cut-out and then running the battery down trying to start it road-side, I'd put it on charge.

Question: will the Motronic (2.2 on the RS) not function unless the voltage is at a minimum? if so what?---Probably on the low side it (the Motronic) will stop functioning properly at below 10 volts & could act up if input voltage is above 16 volts.

 

Question: Could that be why, after attempts at checking wiring looms, component plugs and sockets for corrosion, the bike then started (produced a spark) simply because the battery had reached a critical, minimum voltage?--- If the voltage dropped low enough to allow the Motronic to re-set it m-i-g-h-t allow the Motronic to unlock (assuming it somehow locked itself)

 

The spark circuit is relatively simple, I know, HES pulsing to the Motronic, sending timed pulses to the coil, creating the spark at the plugs - and it makes me wonder about the Motronic unit.

 

Question: Do they fail?

If so, how?---Sure they can fail, I have seen a few fail over the years.

 

That's the one component I can't really test - other than buying/borrowing a new/reconn'ed one.---That is the VERY BEST TEST is to simply install a borrowed or bought KNOWN GOOD Motronic as a test.

(that is usually how I test for a possible failing Motronic)

 

Question: Do beemer engineers have electrical equipment that can test the Motronic?

I've never come across any mention in any of the forums.---NO, not regular BMW engineers. I'm fairly certain their electrical support group at their home engineering headquarters would more than likely have a simulator to test the Motronic but by now their simulators are probably set up for the newer fueling computers on the newer bikes. Some BMW dealers probably have a test Motronic to swap into problematic OLDER bikes as a test (or they borrow one from a good running used bike)

 

HELP! It's driving me nuts! ---Personally I would look on E-Bay or Beemer Boneyard for a good used Motronic. Even if it turns out to not be the problem you should have a working Motronic for the future.

 

Any ideas/feedback/experience/clues would be VERY welcome and much praise would be heaped on any person/s who assists toward a happy ending :-)---First off, WHAT IS YOUR TACOMETER doing just before & during the engine stall??? That is looking glass on your Motronic spark control. If the tac acts screwy just before or during the stall that might point a finger.

 

Next what is the condition & function of you side stand switch?? probably not your issue but should be by-passed or accounted for to eliminate that.

 

Next, test light or lights are your friend on this problem. Make up a panel of 3 or 4 12v test lights & wire to the coil B+ terminal, Motronic B+ input, Motronic ign+ input, etc. Then ride the bike keeping an eye on the test lights. Maybe you can catch a failing or open circuit.

 

NEXT-- at next failure (engine stall) STOP the bike, turn the key off, then remove fuse #5 for a few minutes. Then reinstall the fuse #5 & see if the engine will start (do NOTHING ELSE). If the engine starts that probably means the Motronic is locking itself out. How I don't know but it has that capability.

 

Lastly-- You might PM Roger as he might be able to help you more understand the lock out function.

 

[wimblejon]

Michaelr11, thanks so much for the prompt response.

 

Really interesting to hear of someone with a similar problem. I kind of assumed that if the coil works at all - which it clearly does, it'll carry on working - but if you've had this one TWICE then maybe I should look in that direction now.

 

Frankly I'll look at anything right now!

 

I'll check and let you know.

 

Cheers,

Jon

[Michaelr11]

Jon,

 

My thinking is sometimes a coil will work properly until it gets hot.

 

I never tried this myself, but an interesting test would be applying some type of "cold spray" (freeze spray, electronic cleaner) to the coil right after the engine dies - see if it starts back up.

 

I had a spare coil sitting in my garage so R&R was easiest route for me. I had occasional "sudden engine dies" issues last year, but bike would start back up. A few weeks ago near the end of a ride it would not restart after a brief rest stop. Two hours later it restarted but only ran another 1/2 mile before stopping again. Replaced coil and it has run 1,500 miles since. My buddy replaced his coil about 200 miles ago. He's still doing test rides around the house but I think he'll break free and really test it soon.

[dirtrider]

 

 

 

It had a new fuel filter very recently and a replacement coil from Motorworks.

I checked the usual suspects, a fuel pump cycling when ignition switched on and another cycle when the engine is rotated

 

 

 

Afternoon Jon

 

That would be one freak failure it you originally had the stall & no re-start then you installed that new Motorworks coil & STILL had the exact same stall & no re-start.

[wimblejon]

dirtrider,

Thank you for spending time considering the weirdnesses of my bike problem.

 

Interesting that you think the Motronic ECU can malfunction when others (on other forums) have very, very rarely had one go bad! But I wont discount it as a possibility. I'll probably do all the other, simpler tests first, then if all else fails I'll do as you suggest and beg, borrow or steal one (probably not steal one!)

 

Your comments about the battery and voltages are also very interesting and give me hope that mine is probably OK and that I should maybe look elsewhere,

 

From what I remember, the taco exhibited no strange fluctuations on any of the times when the thing died. It just died! . . .and the side-stand cut-out seems to be working correctly too. It stops the engine when down and allows the electrics to function as normal when up! I tend to drive the bike with the side-stand up anyway!

 

I do like your suggestion of test lights - that should give a better clus as to which part of the circuit is failing - thanks for that.

Also, thanks for the fuse #5 idea, I'll definitely check that one one when I next take the bike out.

 

So, a bunch of things to try and I'll report back the results here ASAP.

 

Thank you again for your time.

 

Jon

[wimblejon]

Michealr11,

Good idea about cooling the coil, another thing I hadn't considered.

I'll probably do some coil resistance checks first and then, if it looks dodgy, either swap it or try the cooling - but to be honest, the coil is buried right up under the front of the tank and to get to it after a failure to spray it would need some fairly nifty disassembly. I'll put it on the list!

Thank you again.

Jon

[roger 04 rt]

...

 

Question: Would a failing battery cut the engine if the voltage drops below a spec'd level? If so, what? Below 9V on the R1150, not sure how low.

 

Every time I brought the bike back home after a cut-out and then running the battery down trying to start it road-side, I'd put it on charge.

 

Question: will the Motronic (2.2 on the RS) not function unless the voltage is at a minimum? if so what? Below 9V on the R1150, not sure how low.

 

Question: Could that be why, after attempts at checking wiring looms, component plugs and sockets for corrosion, the bike then started (produced a spark) simply because the battery had reached a critical, minimum voltage? From your symptoms that does sound like the problem. You said you're getting about 14V while riding.

 

The spark circuit is relatively simple, I know, HES pulsing to the Motronic, sending timed pulses to the coil, creating the spark at the plugs - and it makes me wonder about the Motronic unit.

 

Question: Do they fail? Everything fails to check you'd need to swap in a known good unit, as DR mentioned.

If so, how? Any one of dozens of components inside bites the dust.

 

That's the one component I can't really test - other than buying/borrowing a new/reconn'ed one.

 

Question: Do beemer engineers have electrical equipment that can test the Motronic?

I've never come across any mention in any of the forums.

 

HELP! It's driving me nuts!

 

Any ideas/feedback/experience/clues would be VERY welcome and much praise would be heaped on any person/s who assists toward a happy ending :-)

 

Thanks for listening.

 

Jon

 

One of the most obvious ways you get intermittent spark is an intermittent Fuse 5. Replace it.

 

A second thing to try is swapping the Motronic relay and the Horn relay since an intermittent Motronic relay could cause your problem.

 

I like DR's idea of adding a monitoring LED to the output of the Motronic relay (green/black) if neither a new fuse or swapped relay helps.

 

Also, monitor the green wire at the ignition coil or connect an LED between the green and black wires at the ignition coil (but the flashes are brief and it might be dim).

 

Any of the wires going to/from the Motronic could be damaged. Suspect power, HES and coil trigger wire.

[dirtrider]

 

I'll probably do some coil resistance checks first and then, if it looks dodgy, either swap it or try the cooling - but to be honest, the coil is buried right up under the front of the tank and to get to it after a failure to spray it would need some fairly nifty disassembly. I'll put it on the list!

 

Morning Jon

 

It is difficult to believe that two coils (one new) are acting the exact same way but you can check the secondary side without accessing the coil itself.

 

Just unplug both spark plug wires from the spark plugs then measure the resistance

from one plug wire (plug end) to the other plug wire (plug end). You need to see a total resistance in the 17K-22K range on a room temperature engine. Maybe slightly higher on a hot engine w/hot coil.

 

You need to keep in mind that the BMW under tank ign coil is one of the most robust things on the BMW motorcycle. There were a few issues on the early 1100 (gray colored coils) but even those really never caused many walk home issues as they mostly caused arcing through the case & some misfiring.

 

 

[wimblejon]

Michaelr11, dirtrider, roger 04 rt (and anyone else who is interested . . .)

 

Fixed it!

It was the coil.

 

While the bike was naked and de-tanked I took the coil out to check it and compared the HT side resistances with my spare one (well, the original one, actually!) and the readings appeared similar and within limits - even with the HT leads attached (which have suppressors built in).

The input side (12v) also had slightly different readings, with the one that was in the bike showing the lesser of the two.

I thought I'd try the spare one back in the bike whilst adding a few LEDs led off useful places, such as the coil input, output from the Motronic relay and between the feed from the coil to the ECU. I also swapped the Motronic and horn relays.

 

Not a good diagnostic technique, I know - I should have done one thing a a time - slapped wrist etc etc.

 

However, then taking it for a test ride seemed good - certainly no 5 minute failure (. . . nor 10 minute or so).

I realised that if it was the coil at fault and I'd left it in the bike on test, I'd have seen the LEDs staying on but the spark disappearing, but certainly wasn't complaining that it didn't fail!

 

I've just returned from a 30 mile ride with absolutely NO negative symptoms. If fact, with new plugs, all new filters, new oils, new clutch and balanced carbs, she runs like a f*****g dream. I got my baby back :-)

 

I want to thank you for all the time you took reading and suggesting possibilities but most of all inspiring me to continue the search process - which at times had me pulling what remaining hair I have on my head, out!

 

The promise of a beer still stands - if you ever come to SW London.

If this forum awarded points, I would award the max to you.

 

Thank you.

 

Jon

 

[paul tav]

just read the above as was suffering with identicle issues

early r1100rs so not O2 sensore orcatcode plug , would cut out  after 10 minutes backfire loudly  but restart after a short while   this would increase while trying to get home 

new HES fitted  but made no diference 

what i did notice is 

1 tacho did not flicker or drop when engine cut out

2 rider displsy stayed iliminated and corect 

there was no visusal identification of what could be failing 

but  always had a backfire on start up 

what i did notice is

if the kill switch is oppeerated when running the oil temp goes to max

if the side stand is active the rider display disapears

if the hes plays up the tachodrops

none of the above happened 

but what i did find was the fuelpump relay weak 

when the relay cuts off not only does the pump stop but it also suplies power to the injectors  hence the bike feels like it is instantly switched off 

i have a spare R1100rs so had already swaped coils and motronic unit  but only when i changed the relay did the fault disapear.

 

 

so before  going too deap check the fuel pump relay ,if like me you have no other visual  indications when the bike cuts out give the relay a tap when ticking over 

my bike would misfire  a split second !!!!

but when replaced all good 

regards Paul

 

 

[Michaelr11]

2 hours ago, paul tav said:

so before  going too deap check the fuel pump relay ,if like me you have no other visual  indications when the bike cuts out give the relay a tap when ticking over 

my bike would misfire  a split second !!!!

but when replaced all good 

regards Paul

 

 

Good point.  I had a 1996 1100RT and periodically it would not start. The fuel pump relay would just stop working. Never figured out why, but I always kept a new relay in the glove box.  But my 2001 RT has never had a problem with the fuel pump relay, however it did need to get the coil replaced.

[dave_a]

Me too on I-95.  They also like to cool off and work perfectly when loading the bike on a trailer to take it home too - dirty rotten SOB's!

Hindsight says you can compare the relay resistance in the coil windings to a known good one...like the horn relay. Which is an easy road side switch.

None of this I knew when on the side of the road...

But it was the coil in this case.

And DR gets a free pint when he get to "Ole Blighty". Well deserved IMHO.

 

[dan cata]

If the bike works well when cold but not when hot, it could be a faulty spark plug coil. Have seen them doing that a couple of times over the years.

Usually there are visible cracks on the lower side (as mounted on the bike).

 

Dan.