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95 R1100RSL stuttering under acceleration


JimmR75

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My R1100RSL (74K current mileage) is exhibiting a combination of symptoms that include poor throttle response, "stuttering" under acceleration in the midrange and deteriorating fuel economy (from 45mpg average down to 39mpg). The stuttering can vary in intensity from barely discernable to substantial "misses" or stumbling. It also starts slightly "differently", hot or cold, not the one or two rotations and instant smooth idle that I have been used to.

 

1. All maintenance is current including valve adjustments and TB sync that included cleaning the BBS's. The symptoms above began to manifest before this most recent maintenance. Spark plugs looked good but were not replaced at the time of service.

 

2. I cannot tell if it is one or both cylinders involved when these anomalies occur.

 

3. I recently replaced a failed oil temp sensor and had the HES serviced and rewired by GSAddict. " Thread = 95 R1100RSL Stalling, cutting out, hard to restart" (http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1016460#Post1016460)

 

The symptoms above did not occur for almost 2K miles after these repairs and are entirely different than those exhibited with the failing oil temp sensor. The bike is entirely rideable but there is an obvious change and problem.

 

My next step was going to be replacing spark plugs and removing and cleaning the injectors unless those on this forum have other suggestions.

 

Thanks in advance.

 

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My R1100RSL (74K current mileage) is exhibiting a combination of symptoms that include poor throttle response, "stuttering" under acceleration in the midrange and deteriorating fuel economy (from 45mpg average down to 39mpg). The stuttering can vary in intensity from barely discernable to substantial "misses" or stumbling. It also starts slightly "differently", hot or cold, not the one or two rotations and instant smooth idle that I have been used to.

 

1. All maintenance is current including valve adjustments and TB sync that included cleaning the BBS's. The symptoms above began to manifest before this most recent maintenance. Spark plugs looked good but were not replaced at the time of service.

 

2. I cannot tell if it is one or both cylinders involved when these anomalies occur.

 

3. I recently replaced a failed oil temp sensor and had the HES serviced and rewired by GSAddict. " Thread = 95 R1100RSL Stalling, cutting out, hard to restart" (http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1016460#Post1016460)

 

The symptoms above did not occur for almost 2K miles after these repairs and are entirely different than those exhibited with the failing oil temp sensor. The bike is entirely rideable but there is an obvious change and problem.

 

My next step was going to be replacing spark plugs and removing and cleaning the injectors unless those on this forum have other suggestions.

 

Thanks in advance.

 

Afternoon JimmR75

 

Yes, start with replacing the spark plugs. If that doesn't eliminate the problem then ohm out the spark plug wires all the way through the coil (plug end of wire to plug end on other wire).

 

If high resistance is found in plug wires/coil then make sure that the plug wires are FULLY seated in the coil towers.

 

If plug wire/coil ring out correctly then you should do a fuel return flow test at the fuel return line.

 

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Thanks very much for the quick response.

 

What should I look for as an acceptable range on the ohm reading?

 

Afternoon JimmR75

 

Depends on what coil your bike has but you should be the 18k to 22k range (give or take).

 

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Replaced the plugs, no change in symptoms. Plugs looked fine (color) when removed

 

The resistance from plug end to plug end is in the 25K range.

 

I put almost 200 miles in the past 24 hours and I am wondering if it is "stuttering" not only under acceleration but at constant speed. It does not feel as smooth as normal.

 

I will remove the tank and verify that the plug wires are fully seated and do the fuel return flow test as suggested above, but will appreciate any further suggestions.

 

Thanks in advance.

 

 

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Replaced the plugs, no change in symptoms. Plugs looked fine (color) when removed

 

The resistance from plug end to plug end is in the 25K range.

 

I put almost 200 miles in the past 24 hours and I am wondering if it is "stuttering" not only under acceleration but at constant speed. It does not feel as smooth as normal.

 

I will remove the tank and verify that the plug wires are fully seated and do the fuel return flow test as suggested above, but will appreciate any further suggestions.

 

Thanks in advance.

 

 

Afternoon JimmR75

 

If the resistance from plug end to plug end is in the 25K range then they are making contact with the coil. They might not be fully seated but with 25K resistance they are making enough contact to not be your problem.

 

Probably should do a fuel return hose flow test next then if that is OK do a cranking compression test (#5 fuse removed & throttle held wide open).

 

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Thanks very much dirtrider.

 

1. Is the top line the fuel return?

 

2. Is it just a matter of disconnecting that line and looking for flow when I turn the ignition on?

 

3. Am I correct that the return fuel is not under full pump pressure or do I need to be prepared to capture high pressure fuel flow?

 

4. Am I correct that I will only get a few seconds of fuel flow as the pump energizes and pressurizes the system at key on (no engine start)?

 

I don't want to wind up with fuel spraying everywhere if my assumptions above are incorrect.

 

Thanks in advance for your reply.

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Thanks very much dirtrider.

 

1. Is the top line the fuel return?

 

2. Is it just a matter of disconnecting that line and looking for flow when I turn the ignition on?

 

3. Am I correct that the return fuel is not under full pump pressure or do I need to be prepared to capture high pressure fuel flow?

 

4. Am I correct that I will only get a few seconds of fuel flow as the pump energizes and pressurizes the system at key on (no engine start)?

 

I don't want to wind up with fuel spraying everywhere if my assumptions above are incorrect.

 

Thanks in advance for your reply.

 

Evening JimmR75

 

Yes, upper hose is the return hose.

 

The return line is not under pressure BUT it is supplied by a high pressure source so it can produce a decent fuel flow & it will spray if you restrict it.

 

The fuel pump output pressure is controlled by the fuel pressure regulator (in the 40+ psi range). From the fuel pressure regulator the 40+ psi fuel goes to the fuel injectors then what isn't used goes back to the fuel tank through the fuel return hose.

 

If your bike has quick disconnect fittings in the fuel hoses then you have to disconnect the quick disconnect in the return line then hold the little check valve inside the rear part open to get fuel flow.

 

If your bike does not have quick disconnects then just pull the return hose connector apart, then plug off the one coming from the front, then point the one coming form the rear into a container (or better yet add a length of hose then point that longer hose into a container).

 

Then turn the key on & you should get about 2-3 seconds of fuel flow out of the return line coming from the rear. You can also run the engine to get a better flow test.

 

You need to see about a pencil sized stream of fuel flowing out of the rear return hose.

 

It takes a little over 40 psi to open the return hose to the pressure regulator so IF you get fuel out of the return hose that means that your fuel pump & fuel system IS making the 40+ psi required to run the engine correctly. What you see coming out of the return hose is the fuel quantity supplied to operate the engine so no fuel flow out of the return hose means no fuel available to operate the engine under load. A good fuel return flow means that there is that much fuel available at enough pressure to operate the engine under load.

 

 

 

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1. Disconnected the return hose and connected a hose to the return from the regulator and ran it into a container. Minimal fuel if any on key on (can hear the pump run and see the supply line move pump energizes at key on.

 

2. Reconnected the return line.

 

3. Pulled the supply line coming from the pump and connected a hose to the supply line and ran it into a container. Pencil sized stream of fuel for a few seconds when pump energizes at key on.

 

4. Put a pressure gauge (harbor freight) on the end of the hose connected to the supply line coming from the pump and saw ~90 indicated psi when pump energizes at key on. (Note that this is not a calibrated gauge but indicates fuel pressure.)

 

Is there a diagnostic procedure to identify a potential pressure regulator problem?

 

Additionally, plug color indicates a possible lean condition.

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1. Disconnected the return hose and connected a hose to the return from the regulator and ran it into a container. Minimal fuel if any on key on (can hear the pump run and see the supply line move pump energizes at key on.

 

2. Reconnected the return line.

 

3. Pulled the supply line coming from the pump and connected a hose to the supply line and ran it into a container. Pencil sized stream of fuel for a few seconds when pump energizes at key on.

 

4. Put a pressure gauge (harbor freight) on the end of the hose connected to the supply line coming from the pump and saw ~90 indicated psi when pump energizes at key on. (Note that this is not a calibrated gauge but indicates fuel pressure.)

 

Is there a diagnostic procedure to identify a potential pressure regulator problem?

 

Additionally, plug color indicates a possible lean condition.

 

Morning JimmR75

 

The spark plugs always indicate lean on a modern fuel injected engine operating on un-leaded fuel. You can still somewhat read them but only after a proper hot engine road load run then quick engine chop. Even then it is so subtle that you really need to know what to look for.

 

You can test the fuel pressure regulator as well as the measure the fuel flow quantity at pressure if you want.

 

You will need a TEE installed in the pressure line so you can observe fuel pressure at working flow/regulation.

 

To do a full fuel flow at pressure test just TEE the pressure gauge into the pressure line between the fuel tank & the regulator. Then disconnect the return line at the connector (or quick disconnect). Then plug off the return line coming from the front. Then add a length of hose to the return line coming from the rear & point into a remote container that will hold at least a gallon.

 

Now start the engine & run it for one minute exactly -- on a good functioning system you need to see about 42-43 psi on the pressure gauge for the entire minute & end up with around 1.8 liters of fuel in the container after that same minute. (it doesn't have to be exactly 1.8 liters but should be well over a liter anyhow)

 

I usually use (2) containers using the first one to get the thing set up & running then once running with fuel coming out of return hose I quickly move that return hose to the 2nd container then hit the button on my stop watch, then after 1 minute exactly I move the hose back to the original container then shut the engine down.

 

At 90 psi it looks like your pump can easily make the required pressure but you need to verify that it will maintain 42-43 psi at (about) 1.8 liters a minute fuel flow.

 

If you get the required 1.8 liters but have way less than 42 psi on the pressure line then you probably have pressure regulator issues, if you get & hold the 42 psi but don't get the 1.8 +/- liters out of the return line then you probably have a plugged fuel filter or small split in one of the in-tank pressure hoses.

 

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1. Configured a fuel pressure gauge tee'ed into the pressure supply line.

2. Configured a pair of capture containers and ran a return line to them.

3. Started the bike, started the stop watch, and moved the return line to the second container.

4. The system indicates ~50 psi continuous pressure while the engine is running.

5. The capture system had 1.5L in 40 seconds. I stopped at 40 seconds due to the size of the capture container that I was using, but the return line was producing a steady stream of fuel.

 

I also ran a compression test and had 145 ~ 150 psi on both sides.

 

Unless there is an additional diagnostic to run on the the fuel system, it looks like it passes per the parameters above.

 

I am open to suggestions.

 

 

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1. Configured a fuel pressure gauge tee'ed into the pressure supply line.

2. Configured a pair of capture containers and ran a return line to them.

3. Started the bike, started the stop watch, and moved the return line to the second container.

4. The system indicates ~50 psi continuous pressure while the engine is running.

5. The capture system had 1.5L in 40 seconds. I stopped at 40 seconds due to the size of the capture container that I was using, but the return line was producing a steady stream of fuel.

 

I also ran a compression test and had 145 ~ 150 psi on both sides.

 

Unless there is an additional diagnostic to run on the the fuel system, it looks like it passes per the parameters above.

 

I am open to suggestions.

 

 

Morning JimmR75

 

It does look like your bike passed the fuel flow/pressure test with flying colors.

 

We will have to find something else to look at next -- I will have to re-read the entire thread to see if we can figure out where to look next.

 

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My next suspects are dirty injectors or worn throttle bodies, but I am open to suggestions.

 

I have seen threads that describe simple injector cleaning. Are the injectors as easy to remove as they appear or is the fuel supply connection more problematic than I realize?

 

 

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My next suspects are dirty injectors or worn throttle bodies, but I am open to suggestions.

 

I have seen threads that describe simple injector cleaning. Are the injectors as easy to remove as they appear or is the fuel supply connection more problematic than I realize?

 

 

Morning JimmR75

 

Probably not worn throttle bodies as that causes more of an idle issue than a mid range rideability issue.

 

I definitely could be dirty injectors-- they do come out easily IF everything is still supple & compliant. Old hardened "O" rings can make removal more difficult so don't break an injector by forcing it.

 

Can you give us some idea on WHEN the problem started (like after bike storage or after a certain occurrence?)

 

Have you done a compression test lately?

 

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This problem began 1K+ miles or so after resolution of a problem that turned out to be a failed oil temp sensor (See the original entry in this thread for details on that). I had the HES tested and re-wired by GSAddict at that time as well.

 

The bike was off the road for a couple of weeks during that process but is ridden regularly and used year round as much as possible for my daily commute (60 mile round trip).

 

Compression tested 145 ~ 150 psi on both sides yesterday.

 

New plugs, full valve adjustment and throttle body sync as part of troubleshooting this current problem.

 

 

 

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Information update: I am getting feedback pointing at plug wires as a possibility. The ignition ohm'ed out around 25k from plug cap to plug cap.

 

Is this conclusive enough or is their a more thorough diagnostic that can be followed on the ignition.

 

The HES was tested and rewired less than 90 days ago by GSAddict.

 

Thanks in advance for any input.

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Information update: I am getting feedback pointing at plug wires as a possibility. The ignition ohm'ed out around 25k from plug cap to plug cap.

 

Is this conclusive enough or is their a more thorough diagnostic that can be followed on the ignition.

 

The HES was tested and rewired less than 90 days ago by GSAddict.

 

Thanks in advance for any input.

 

Morning JimmR75

 

That 25k ohms is in the ball park for decent spark plug wires & the early BMW 1100 coil. That tells us that you don't have any opens or shorts & the wire internals are probably still OK.

 

What the resistance test doesn't show is any sort of arcing to ground under load, either in the coil, or in the plug wire runs.

 

So inspect the plug wires for cuts, abrasions, contacting the R/H throttle body cam, (about any place they could short or arc to ground).

 

On the coil arcing internally-- that is difficult to tell anything even with a close inspection so about the only recourse there is to replace the coil (just as a precaution). If your bike had the late 1100 coil (or a replacement coil) then I would say that it probably isn't the problem but with you having an early 1100 bike, if it still has the original coil, then a that is always a possible failure point & could easily be causing your problem.

 

Another thing to check for is that your o2 sensor pig tail is not running along, or close to, the R/H spark plug wire. If it is then THAT can really cause engine runability issues (usually at or close to idle though).

 

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I am currently working on a 1100 GS with about the same symptoms. The bike starts hard and revs intermittently when reaching ~ 3000 rpm.

 

I changed the spark plugs and the fuel pump + filter. Checked the injectors, they do spray I would say normal...

 

The bike sat for a long time unstarted. I also changed the air filter, without any luck... Bypassed the sidestand switch, no change...

Wondering if the root cause is the same... :D

 

Dan.

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Status update: Strong possibility that dirty fuel injectors are the source of this problem.

 

I removed the fuel injectors and cleaned them using a 9-volt battery as a power source, carb cleaner sprayed through the injector, followed by compressed air (gently) to clean and dry. (No credit claimed, found this procedure online)

 

It was too late last night to test ride but during the commute to work this morning in intermittent rain it ran smoothly and did not exhibit the issues I have been chasing. Startup was back to the normal 1 or 2 rotations and smooth idle that I have been used to. Fuel mileage will be the final indication that all is well.

 

My commute is 30 miles one way so by this evening I will have 60+ miles on this possible solution and will update further at that time.

 

As always, the input here is instrumental in my troubleshooting process. I hate to throw parts at something unless I have a strong indication that they will address the problem. This is my first fuel injected bike after 25 years on an airhead (R75/6) so my troubleshooting skills are still developing. The advances in technology are like going from the Wright Brothers at Kitty Hawk to the Starship Enterprise, but the 1100 is an amazingly capable motorcycle.

 

I helped my son-in-law change a thermostat on a Ford Focus this week. The process involved removing the coolant recovery tank, a motor mount, and the power steering pump. Even after all that prep there was barely enough room to get the thermostat bolts out. I told him that his Focus was designed to be assembled, while my German bikes were designed to be maintained and repaired.

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Just shy of 100 miles today after cleaning the fuel injectors last night and that seems to have resolved the issue. Starting and idling are back to normal with clean acceleration at speed.

 

Thanks to all here for their input and suggestions.

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The GS I am working on is still not fixed. Changed the injectors and it works the same.

It starts hard and when revving, it stutters, cannot be ridden.

 

I decided to get it opened again, checked the HES plate, there were some small rocks falling down from there when I opened the black plastic cover. I thought that was the problem, destroying the sensors and I rebuilt the HES plate. But the bike runs the same.

 

Asked the owner again when this has started happening and he said he fell off the bike in a small crash and then was the moment when the bike started to run like it now does... The bike looks mechanically perfect, from the outside.

I am thinking about replacing the coil and opening the starter motor and checking the magnets, apart from that... not sure what else I can check.

 

Dan.

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The GS I am working on is still not fixed. Changed the injectors and it works the same.

It starts hard and when revving, it stutters, cannot be ridden.

 

I decided to get it opened again, checked the HES plate, there were some small rocks falling down from there when I opened the black plastic cover. I thought that was the problem, destroying the sensors and I rebuilt the HES plate. But the bike runs the same.

 

Asked the owner again when this has started happening and he said he fell off the bike in a small crash and then was the moment when the bike started to run like it now does... The bike looks mechanically perfect, from the outside.

I am thinking about replacing the coil and opening the starter motor and checking the magnets, apart from that... not sure what else I can check.

 

Dan.

 

Morning Dan

 

Did you do a fuel return hose flow test? If not than do that.

 

If a fuel injected BMW oilhead falls over hard enough it can crack the plastic fuel pump outlet fitting due to the mass of the fuel pump violently rocking the fuel pump in it's mount.

 

A cracked fuel pump outlet fitting will really lower the fuel pressure to the fuel injectors.

 

If the return flow is not the problem then look for water in the fuel. If there was any water in the fuel tank sitting down in one of the tank wings then a simple tip over can allow that water to mix with the fuel in the tank.

 

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I have already changed the pump and fitted a new fuel filter...

Water inside the tank... I doubt, since the bike was running fine before the crash...

 

Dan.

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Is it possible the timing cup glued to the pulley got dislodged, creating a timing problem? Easy to check with LED test setup. Without LED you might try changing the timing one way or the other to see if it helps.

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Dan, Do you have a gs-911?

 

Also, the return flow test DR asked about will check the hoses, something that hard to tell by looking at them.

Edited by roger 04 rt
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Unhofliche_Gesundheit

t

I am currently working on a 1100 GS with about the same symptoms. The bike starts hard and revs intermittently when reaching ~ 3000 rpm.

 

Hi Dan: that somewhat describes how my bike ran when I disconnected the fuel injector connector to get a wrench/spanner in to adjust the throttle body. Forgot to reconnect the connector and bike ran like crap, hard to start, only ran at higher rpm- noticed my mistake and instant fix.

i.e. sounds like maybe you, like I was temporarily, running on one cylinder.

You may consider starting and running bike a minute or two and then using your hand to see if on one side the cylinder head / exhaust pipe is hot while other side is not.... identify problematic side.

Just a possibility.

Regards.

 

 

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@Unhofliche_Gesundheit, that is exactly how my bike runs, like it would only work in one cylinder, only that intermittently.

 

@James in OK, I thought of that too, because it has happened to me a couple of years ago, only the bike would not start at all back then. The bolt somehow came loose and the cup key got bent, I had to order a new cup.

 

@Roger, would a visual check of the injectors spray pattern suffice, when cranking the bike? I do not have fuel pressure devices, bot I guess I can order one to have for the future.

 

 

I do have a Gs911 but I have the wifi version, and no longer the old yellow one with the 1100 adapter. I used to read the error codes using an analog DVM that I bought from an old guy for ~ 2.5$ :D I also have a LED and resistor for reading the pulses trough the diagnose connector, but for some reason, on this bike, it does not blink for the ABS or the Motronic wires...

 

Last night, I think I got to the bottom of it. I disconnected the O2 sensor connector and plugged the red/pink CCP. the bike started just fine and ran fine, no more hiccups. I only started it inside and did not get to ride it, but it sounded normal.

I ordered a used O2 sensor from a donor bike, that I hope I will be getting today, plug it in and see if that solves the problem for good.

 

Will let you know.

 

Dan.

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Dan, Measuring return flow doesn't require a pressure gauge. Just connect a hose to the upper pipe coming from the fuel distributor and measure the quantity in one minute. It should be 2 liters with the engine at idle.

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Right. Will do that...

 

I mounted the new O2 sensor and the bike runs the same, meaning poor. The spark plugs, although new, are covered in a black sooth.

I do not understand why if I take off the L/H spark plug wire, the bike still starts and runs. Not the same happens if I take off the R/H side wire...

Fuel squirt seems normal, the pattern is as usual. Took the valve covers off, the lash is within spec.

 

Will measure the flow on the return then... Tomorrow evening...

 

Dan.

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I do not understand why if I take off the L/H spark plug wire, the bike still starts and runs. Not the same happens if I take off the R/H side wire...

 

Dan.

 

Afternoon Dan

 

You might also measure the resistance from one spark plug wire metal clip (the part that snaps on the spark plug top) to the same spark plug metal clip on the other side (ie all the way through one spark plug wire through the coil & through the other side spark plug wire.

 

You need to see a resistance in the 18k-25k range if your bike still has the original early gray coil.

 

If you find an open then one of your plug wires is probably pulled partially out of the ignition coil or you have a bad plug wire.

 

Also, make sure that your R/H side plug wire is not contacting the R/H side throttle body cam & wearing through the insulation.

 

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Another evening, the same result :)

 

Measured the resistance, 18.4 kohms, so I would say it is within specs. But I have also replaced the coil and the wires, and it works the same.

I did the flow test, it does fill 2L in 1 minute at idle speed. Drained all the gas in the tank, it looks fresh, no water inside, etc.

I have noticed that if I prime the pump a couple of times, it looks like it is working fine for a couple of seconds, then it doesn't. So I thought it has to do with the fuel pump or similar and changed it again for a new one. the bike runs the same...

 

So, it starts normal, idles normal, but when revving hard, it stumbles and dies. If revving slowly, it works normal. All tests were done with the bike at neutral, if I want to test ride it , it is unrideable...

 

Dan.

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Another evening, the same result :)

 

Measured the resistance, 18.4 kohms, so I would say it is within specs. But I have also replaced the coil and the wires, and it works the same.

I did the flow test, it does fill 2L in 1 minute at idle speed. Drained all the gas in the tank, it looks fresh, no water inside, etc.

I have noticed that if I prime the pump a couple of times, it looks like it is working fine for a couple of seconds, then it doesn't. So I thought it has to do with the fuel pump or similar and changed it again for a new one. the bike runs the same...

 

So, it starts normal, idles normal, but when revving hard, it stumbles and dies. If revving slowly, it works normal. All tests were done with the bike at neutral, if I want to test ride it , it is unrideable...

 

Dan.

 

Morning Dan

 

With the bike sitting for a long while before the problem showed up sort of points to a fuel problem, or fuel restriction, but your testing & injector swap doesn't seem to show that as the problem.

 

Does it seem to be firing on both cylinders as you revv it? (ie are both side exhaust pipes the about the same temperature?)

 

Is the temperature gauge reading correctly? There is a possibility that your oil temperature sender isn't working correctly or possibly you knocked the connector loose when accessing the HES.

 

Have you tried running it with the o2 sensor completely disconnected? If not then try that.

 

You might also put a voltmeter on the TPS (Throttle Position Sensor) to make sure it is tracking smoothly & correctly.

 

Kind of a long shot but any chance that the exhaust system is plugged up? (does the exhaust note sound normal or sound over muffled & weak?)

 

If you don't know the history if the bike then maybe verify that the cams are both still perfectly in time (probably tell by the little arrows on the cam sprockets).

 

Also wouldn't hurt to do a cranking compression test. (with fuse 5 removed & throttle held wide open)

 

Are you getting full system voltage to BOTH side fuel injectors?

 

 

 

 

 

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Morning Dan

 

With the bike sitting for a long while before the problem showed up sort of points to a fuel problem, or fuel restriction, but your testing & injector swap doesn't seem to show that as the problem. right...

 

Does it seem to be firing on both cylinders as you revv it? (ie are both side exhaust pipes the about the same temperature?) same temp, hand tested them, the cylinders feel the same

 

Is the temperature gauge reading correctly? There is a possibility that your oil temperature sender isn't working correctly or possibly you knocked the connector loose when accessing the HES. Will verify that... Perhaps it was not me the one who disconnected it, the tank has been recently painted.

 

Have you tried running it with the o2 sensor completely disconnected? If not then try that. I did and it runs perfect with the O2 sensor unplugged.

 

You might also put a voltmeter on the TPS (Throttle Position Sensor) to make sure it is tracking smoothly & correctly. TPS is fine, swapped it with another one it it works the same.

 

Kind of a long shot but any chance that the exhaust system is plugged up? (does the exhaust note sound normal or sound over muffled & weak?) Could be, never heard of that but will try it out...

 

If you don't know the history if the bike then maybe verify that the cams are both still perfectly in time (probably tell by the little arrows on the cam sprockets). Adjusted the valves last night, so now in spec.

 

Also wouldn't hurt to do a cranking compression test. (with fuse 5 removed & throttle held wide open) Will try that too, I have the tool.

 

Are you getting full system voltage to BOTH side fuel injectors? Both injectors squirt gas when cranking. Took them off one at a time.

 

Answers inline.

 

Thanks,

Dan.

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Have you tried running it with the o2 sensor completely disconnected? If not then try that. I did and it runs perfect with the O2 sensor unplugged.

 

Morning Dan

 

THIS!, is telling us something.

 

I think that you tried a different o2 sensor (correct?). Maybe that one is also bad.

 

As a rule when they run better with the o2 disconnected then there is a problem with the o2 sensor, or a stray RFI signal is getting into the Motronic through the o2 sensor wiring. (is the o2 sensor wiring running along or near the R/H spark plug wire or close to the coil?)

 

How does it run with the o2 sensor connected but the CCP removed from the fuse box?

 

 

 

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Will post updates tonight regarding the disconnected O2 sensor, w/ and w/o the CCP. The donor O2 sensor came off a working bike, so I guess both sensors are fine. The wire runs as usual, trough the gearbox lower mounting bracket, then the small bracket behind the air induct and onto the R/H metal pipe, where the coil is. It is the normal routing as you would find it on any working bike...

 

Dan.

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Will post updates tonight regarding the disconnected O2 sensor, w/ and w/o the CCP. The donor O2 sensor came off a working bike, so I guess both sensors are fine. The wire runs as usual, trough the gearbox lower mounting bracket, then the small bracket behind the air induct and onto the R/H metal pipe, where the coil is. It is the normal routing as you would find it on any working bike...

 

Dan.

 

Morning Dan

 

Just make darn sure that the o2 sensor pig tail wire is not running along or near the R/H spark plug wire (BMW had a service bulletin on that for the later Boxer bikes).

 

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Tried to re-route the O2 wire, not to be in the proximity of the spark plug wire. Pretty hard to do since they are both on the same side, going to about the same place... This change did not have any impact.

Disconnected the O2 sensor and tried running the bike like so, with and without the CCP. The bike still ran like crap.

 

Then I tried to measure the compression on both cylinders, it was in the green zone of the gauge, so OK. Then I tried to see how it runs with the old spark plugs: #1022040 - 11/05/18 04:15 PM I mentioned I have changed the spark plugs.

 

For some reason, when ordering them, I ordered from the supplier app based on the bike type model and year, instead of searching for equivalents for fr6ddc as official from BMW. So I ended up with some plugs that say RC8DMC...

When putting the old plugs in, the bike ran PERFECT, as a normal 1100GS should...

 

So the app gave me wrong plugs and I mistaken them to be good for the bike, when they actually were not...

 

So now, the bike does run and I have learned some new things about oilheads in the process.

 

Thanks to ALL!

 

Dan.

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