Long: Nobody can figure it out, -got any ideas?

[fiddles]

:blah :type
Ok, I've waited a while to finally post this desperate plea for help, so I'll probably forget some details- but I'll answer any questions, etc...

I'm determined to see this through- I do have an appointment later this month with another dealer 100 miles away who seems confident, but I thought I'd try my luck here.

Oh, yeah- today's my Birthday- so cut me some slack, as I'm still young and dumb!

My first BMW, a 1999 r1100s, 2nd owner, purchased in February 2008, currently 113,xxx miles (purchased with 110,990).
The Dealer, after I spent a small fortune there, basically threw their hands up and said, "I don't know what it is, good luck." I don't feel they really gave it the old college try, IMHO...

While riding at speed, the bike will begin to lose power and not respond to throttle. The rpms will drop and then kick back (all while applying the same throttle) like a bucking bronco- completely unrideable. It will get to the point that it'll start to die if any throttle is applied at all, and I've found myself having to idle home several times. It'll even start to do this within 30 yards of my house when leaving and only going 20 mph. Seems that every time any part is replaced or service is done on the bike it will run fine for awhile (20 miles or so, up to 2-3 weeks of riding) then the problem resurfaces.

First owner had same problem intermittently (we discussed it at length before I purchased the bike), and I will cut and paste his posts on the problem below- I'd rather not link to his posts or give his username without his permission. I understand he went through several motronics, a O2 sensor, TPS, and new Hall sensor trying to fix it. He believed it was fixed upon selling it to me (and it appeared it was).

The PO took very good care of the bike, followed Paul Glave's advice carefully and completely, and was an electrician who went over the bike's electronics thoroughly- here are the PO's posts on his problem (he probably describes it better than I could, same problem).

12/06- [All from same thread] (Previous Owner)
"Here I go again...my '99 1100sa, 111K miles...recurring problem for last 30-40K....sudden power loss while at a constant speed or under acceleration. I've changed 3 motronic units....solves the problem for 10k and then resurfaces again. About a year ago Hall effect sensor was diagnosed as the problem and replaced, but with no assurances that this was the problem. It tested good, failed the next test, passed the third, replaced it anyway.Sounds like a connection problem to me. I ordered a wiring diagram for it and will check every connection/plug for corrosion. Contact cleaner and No-Ox for connectors. Any other thoughts out there? The motronic connections are good. I believe it is a contact or a corrosion problem, as bmw treats copper conductors as precious metal and goes with the smallest conductor possible.."

"Doesn't die, just seems to go into one of those "limp home" modes....won't accept throttle...stumbles over itself, seems to catch it's breath in a few seconds and accelerates poorly. Then it'll clear itself out and be fine for a few minutes and repeat itself.....No codes on the Motronic either...no ABS blinking lites either showing fault....I replaced the Motronic with a salvage one a few years ago, all was well, next year same thing, no codes either, BMW sent me upgraded Motronic unit from Germany directly. All was well til last summer, new dealer has new Mechanic, Phil, Master tech supposedly. great guy....Dignosed it as Hall sensor possibly....swapped it out, all was well for 15-20K til now..."

"A few times a season I'll run 2-3 tanks with the proper amount of Chevron Tekron fuel SYSTEM cleaner, not injector cleaner, as per Paul Glaves and the late Rob Lentini... We've pulled the injectors and checked the spray patterns on a piece of cardboard while cranking engine... seems fine... haven't changed the fuel filter in a while. Can't hurt. The idea of a coil breaking down sounds interesting.... hadn't considered that....I'll try that direction too. I gotta believe it is electrical, comes and goes..."

"Replaced the TPS about 10K ago... Rode it hard today for a few miles and all is well... grrrrr... I'm gunna swap out the fuel filter and see what that does... it usually occurs after sustained high speed running, I travel Interstate home from work for 15 miles or so and midway home it'll act up... if it's fuel pressure that should solve my problem if pump is ok I think....."
__________________________________________________ ____________
03/07
"'99 1100SA.....continuing problem....runs great initially, say 20 minutes or so, then it'll start to run eratically. Won't accept throttle above idle. It runs, but Very rich, to the point of puking soot out the pipes. I also notice it will run great for 20 minutes or so, if I shut it off for say 10 minutes, restart it, won't accelerate, goes full rich. My guess is either the oil temp sensor on the top front of the motor sending signal to Motronic or the O2 sensor. Any suggestions? Oh yeah, 111K...new plugs/wires. Coil resistance checks ok, compared to others....gotta believe it's a temp sensor malfunction...."


Here's the list of what I've tried so far-

- When I first got the bike, I rode it flawlessly for a few days before taking it in for the following- New air filter, all fluids changed, new plugs, new battery, new oil sight glass, brakes bled, TB synch and valve adjustment. The bike continued to run fine, taking me on a 600 mile trip to Branson Blitz, and probably 1300 miles or so total before it acted up for the first time.

- Fuel filter, this was the first "fix"- presumption was bad gas. Worked for a week or two, maybe longer. Have also ran some BMW injector cleaner and Chevron System cleaner through.
- Problem came back, and we replaced the spark plugs (again), and put in new wires. Also put in a new (low mileage used) Cat. Didn't really seem to help.
- Somewhere along the way another problem came up (may or may not be related), which was an intermittent starting problem- the bike would turn over very slowly and not catch, even though the battery is new and fully charged. If I would turn the key back off and try again, I could start it anywhere between the 2nd and 12th attempt. This Problem seems to have been fixed upon replacing the Fuel Pump (below).
-Dealer tested the TPS, it tested fine. After plugging it back in, they test rode the bike and it ran fine. They told me it might have been a dirty or bad connection in the plug for the TPS (although it looked fine). Bike ran fine for a few weeks before it came back again.
- I then found a user on ADV who has a similar problem with his 1150GS, so I replaced my Fuel Pump (and filter again), and it ran fine for 23.8 miles before bucking again.

I may have done more to it, and forgotten to add it into this post. :blah

I've gotten as many different ideas from as many people as I've spoken with, and I'm kind of spinning in confusion. I've heard Hall Sensor, TB Sync, O2 sensor, TPS, Pressure Regulator, bad electrical connection, and others I don't remember...

I'm hoping someone out there has seen this problem before- or has an educated guess, as I'm running out of money and patience replacing parts on the bike.

Anyone who actually displayed the patience to read this whole post deserves an award.

John

[41107]

have you ever checked for a vacuum problem in your gas-tank?When it starts bucking pull to the side of the road and try opening the gas tank lid.There should be no air rushing into the tank.If so check for pinched breather hose.

[pffog]

have you ever checked for a vacuum problem in your gas-tank?When it starts bucking pull to the side of the road and try opening the gas tank lid.There should be no air rushing into the tank.If so check for pinched breather hose.

My thoughts as well, also is there something floating around in the tank, intermittently blocking the fuel pump inlet screen??

Several years (like 35) I worked at a Saab dealership, we had a guy come in with very similar symptoms, (they used a Bosch EFI system as well), the guy was a real PIA from the start, he too had taken it to several mechanics before showing up on our doorstep. Well what we found was pieces of a credit card slip from a gas station floating around in the tank. They would float away from the pick up screen when the car was shut off and then replug the screen after several miles, making the car un-drivable.

The guy wanted Warrenty, even after we showed him the pieces of the receipt, and told him it was hardly a manufacturing defect.

The receipt was from a service station very near his residence, so we figured he was as much of a PIA to some attendant, so the attendant stuffed the receipt in the tank.

[fiddles]

have you ever checked for a vacuum problem in your gas-tank?When it starts bucking pull to the side of the road and try opening the gas tank lid.There should be no air rushing into the tank.If so check for pinched breather hose.

I'm fairly certain the hoses are free and clear, but I did also have a small fuel leak (seep) in the tank around a bracket weld on the underside. This was one of the first things we fixed also. It's certainly worth looking into.

My new goal is to get it going in time for the Falling Leaf Rally.

Did I mention a free lb. of Coffee goes to the person with the fix? PM me your address if you're ultra- confident!

[brainfish]

This may seem a bit off but check your throttle cables and the fast idle cables, even check the bowden box under the tank. A cable maybe hanging up now and then.
Happened to a friend, I just cauaght it out of the blue. The right cable was hitting a cable tie and the ferrrel would hang up

[fiddles]

My thoughts as well, also is there something floating around in the tank, intermittently blocking the fuel pump inlet screen??

Several years (like 35) I worked at a Saab dealership, we had a guy come in with very similar symptoms, (they used a Bosch EFI system as well), the guy was a real PIA from the start,

I did visually inspect the tank upon installing the pump and filter, although the r1100s tanks are unusually shaped, so that's probable... I don't want to be "that" guy.
Tank removal on it's way.

One of my main problems might be assigning too much credit to others that have worked on my bike, meaning that I overlook the simple thinking those before me would have already ruled it out.
Like I said, I'm young and dumb. You worked at the Saab Dealership more years than I've lived.

[billpierce]

Some of the early r1100s had a problem in the wiring harness created by a cable tie near the steering head that is too tight. In time it breaks a wire. I would check that out.

also do a search and post here
http://forums.pelicanparts.com/forumdisplay.php?forumid=24

[fiddles]

I didn't mean to double post...
My thoughts as well, also is there something floating around in the tank, intermittently blocking the fuel pump inlet screen??

Several years (like 35) I worked at a Saab dealership, we had a guy come in with very similar symptoms, (they used a Bosch EFI system as well), the guy was a real PIA .
That's probable, tank removal coming up.

This may seem a bit off but check your throttle cables and the fast idle cables, even check the bowden box under the tank. A cable maybe hanging up now and then.
Happened to a friend, I just cauaght it out of the blue. The right cable was hitting a cable tie and the ferrrel would hang up
I checked the cables at the TB end, but not at the bowden box. Good idea...

[DarrylRi]

Here's another thought: your charcoal cannister may be blocked. This creates a vacuum situation in the tank after about 10 minutes. If this is the problem, you will find the tank difficult to open against the vacuum, after the motor has been running a while. On a plastic tank bike like my R1100RS, it will actually suck the tank inward from the fairing panels.

Search for "cannisterectomy" to find out how to remove it, if this turns out to be th problem. You will probably find a description of why it happens too.

[fiddles]

Here's another thought: your charcoal cannister may be blocked. This creates a vacuum situation in the tank after about 10 minutes. If this is the problem, you will find the tank difficult to open against the vacuum, after the motor has been running a while. On a plastic tank bike like my R1100RS, it will actually suck the tank inward from the fairing panels.

Search for "cannisterectomy" to find out how to remove it, if this turns out to be th problem. You will probably find a description of why it happens too.

Forgot to mention the canister was removed quite some time ago...
:doh

[108625]

I'm just curious, did you look at the spark plugs when they were replaced?
Next time this happens, stop the bike (where safe) and let it cool off enough to take them out and examine. There won't be a complete diagnosis there, but you might at least get a sign of what's been going on in the combustion chamber.
If they confirm a rich condition, you can probably rule out a fuel starvation issue.
I'm inclined to suspect a problem with an excessive fuel supply or a weak spark, based on your (and the previous owners) descriptions. With most of the ignition system having been replaced at least once already, too much fuel seems a more likely (likely, not definite) answer. In addition to the sooty black exhaust, how does it smell? Does it make your throat burn and eyes water?
How about this test; when the bike seems to be running normally, turn on the "choke" (fuel enrichener circuit) and see if it behaves similarly to when it's acting up.

Good luck,
Bob

[Raceydog]

I was talking to a club member the other day and he mentioned similar symptoms on his older GS. He discovered the tank liner material had separated from the inside of the tank and was blocking the fuel screen/pickup. If it is, strip the inside of the tank after cleaning out all fuel and liner material. Then reline with Kreem or a similar tank liner.

[fiddles]

I'm just curious, did you look at the spark plugs when they were replaced?
Next time this happens, stop the bike (where safe) and let it cool off enough to take them out and examine. There won't be a complete diagnosis there, but you might at least get a sign of what's been going on in the combustion chamber.
If they confirm a rich condition, you can probably rule out a fuel starvation issue.
I'm inclined to suspect a problem with an excessive fuel supply or a weak spark, based on your (and the previous owners) descriptions. With most of the ignition system having been replaced at least once already, too much fuel seems a more likely (likely, not definite) answer. In addition to the sooty black exhaust, how does it smell? Does it make your throat burn and eyes water?
How about this test; when the bike seems to be running normally, turn on the "choke" (fuel enrichener circuit) and see if it behaves similarly to when it's acting up.

Good luck,
Bob

Every time I've looked at the plugs they've been normal (tan, dry)- admittedly I haven't examined them immediately after the problem.
I do notice a gassy smell during the first 10-20 minutes of riding, usually at stop lights. During the first week of ownership of the bike, I pulled over to the side of the road to look at some sign or something, kept the bike running for 100 seconds or so, and when I went to leave, the bike wanted to die as I gave it throttle. I momentarily freaked out, then noticed the idle adjustment lever was still up (after 10 miles or so), turned it "off" and continued without incident. I only had to go another 100 yards or so to my destination, where I stayed for 15 minutes. Of course, at the time, still being new to BMW's, I thought it was a "choke" and figured that was why I had a problem. It wasn't until weeks later that the issue returned, and I never really felt there was a relationship.
As an aside, I've also thrown in the autoelite plugs, and noticed no difference.

I've also successfully made the bike act up in neutral, on the centerstand, by applying constant throttle to about 3,500 to 4,000 rpm- only once though.

As far as the tank liner, the tank's aluminum, and I'm not sure if there's a liner at all, but that would be similar to something blocking the intake screen also.

[alien_hitchhiker]

As a counterpoint to the debris in the gas tank suggestion;

have you inspected the lower compartment of the airbox for anything that might be intermittently obstructing flow to one of the air intake tubes?

A long shot for sure, but why not? This would fit with the running too rich behavior.

[GSAddict]

Another long shot but.......
I have twice seen the inner core of a fuel line torn into a 'flap' which at certain times would block the fuel flow. In one case it caused almost complete blockage, in the other a restriction that affected high rpm operation only. It is not that expensive to change all the lines (outside as well as inside the tank). I just did mine as it is a '00 and was due (piece of mind - I don't like old fuel line especially at fuel injection pressures)

[Dave_Faria]

Check the main battery ground connection on the engine body. A bad ground when warm can increase in resisitance which can cause electronic problems plus limit starting current to the starter motor. My ground on my 04RT is VERY difficult to check. It is located under the ABS modulator(left end) and I suspect that is where yours is also.

Good Luck
Dave Faria
Austin, Tx

[bikerfish1100]

not the tank liner- there is none on the S model; solid aluminum.
not the fast idle control; it does not "enrich" anything, it just raises the idle. you could ride the entire life of the bike with it on, won't do a darn thing.

sounds like it might be electrical- if not getting a full charge, the FI will act as you've described. i know you said the HES was replaced- have you checked the wiring into the HES? that's a weak point on oilheads, it tends to break apart, and can act up when warm.

also, raise the question over at Pelican, maybe one of the S masterminds can help you trace it down. http://forums.pelicanparts.com/forumdisplay.php?s=&forumid=24

[lostboy]

Have you tried replacing the oil temperature sensor? These can become intermittent and not throw a fault.

[108625]

Coffeeguy,
I suggested the spark plug read immediately after the bike acts up because normal running afterwards can obscure "fresh evidence".
(It is the old school way of jetting dirt and race bikes; get to normal operating temp, wind up to wide open throttle under load and hit the kill switch while squeezing the clutch so you don't lock up the rear wheel and slide. Read the plug then. You will even be able to see a line where the last arc contacted the ground electrode.)
In your case, killing the engine when it's running rough and plug reading could show you more signs of rich running (or another symptom) than a random exam when they're being replaced, which only gives you a more "overall" picture.
If my "choke" test suggestion wouldn't work, yeah, it's old school and shade tree, but not neccessarily barking up the wrong tree. You're describing a situation where the air, fuel, spark balance is off part of the time, either heavy on the fuel side or light on the air or spark sides. Isolating which of these three variables is the culprit is a step towards solving it.
It may be as simple as a mouse nest in your air filter or dirt in your system interfering with an injector opening and closing correctly, or as complicated as some portion of the engine management system receiving/misinterpreting/sending the wrong signal to your throttle bodies and/or ignition.
Between now and your visit to the more optomistic sounding mechanic, I would suggest you write everything down for them, (in case you forget to tell them some detail or another, plus they can keep going back to your written observations after you've left the shop).
I would also check as much as, and try every test you can without any making any changes that could affect their diagnosis. Some of the simpler stuff could save you a few hours shop labor.

Good luck & let us know who gets the coffee,
Bob

[fiddles]

You'all know your stuff. I got ahold of a truck to take the bike down to the other dealer, but I'm still going to investigate all suggested possibilities until then (9/13). I also meant to add that I'll be printing this entire thread, as well as other documented info I have, and taking it down to the dealer. That way, they might get some ideas from the suggestions given, or at least they'll have more information to guide them.
One of the problems I've noticed in countless searches I've done on various forums looking for similar cases is that often the original poster doesn't reply with the solution- so I'll make sure I follow up.
But keep the ideas coming if there are more, and thanks.

John

[pffog]

Back to the theory it is a fuel delivery (pump) lines, filters, regulator)

I would think with about $20 you could devise a fuel pressure gauge to monitor the pressures in the system, should just need a tee, hose and a cheap gauge.

ANY of the above mentioned fuel issues would manifest itself with lowered pressures. Once that is confirmed/eliminated your trouble shooting job just got easier.

Too often when troubleshooting we look for the problem in a shot gun fashion, sometimes it is quicker to eliminate what is isn't to narrow down the target.

[GSAddict]

Back to the theory it is a fuel delivery (pump) lines, filters, regulator)

I would think with about $20 you could devise a fuel pressure gauge to monitor the pressures in the system, should just need a tee, hose and a cheap gauge.

ANY of the above mentioned fuel issues would manifest itself with lowered pressures. Once that is confirmed/eliminated your trouble shooting job just got easier.

Too often when troubleshooting we look for the problem in a shot gun fashion, sometimes it is quicker to eliminate what is isn't to narrow down the target.

Ditto your comments. I just thought that somewhere down this long saga of dealer attempts one of them MUST have tried monitoring the fuel pressure while riding, but maybe that is not the case..........Easy to rig up a setup for sure.

[fiddles]

Although the tech isn't 100% certain, he believes he fixed the problem. (I say not 100%, because he can't get the bike to act up anymore, but he's been riding it every day just to be sure).
Looks like the issue was the O2 sensor wire, which was routed incorrectly. Apparently, he's seen this issue before and there was a recall several years ago for several models affected.
My limited understanding (by phone) is that the O2 sensor wire was too close to a spark plug wire, and that this can cause all sorts if running issues, mine included. He also said these issues can present intermittently as well. The good news is that this will hardly cost me anything, and the better news is that my bike may be fixed, and I can ride it to the Falling Leaf Rally! :dance
Although I'll still have to pony up for the tire change, spark plugs (autolite), and the slight adjustment to the TPS. But, I can live with that.
I can't say enough about Grassroots BMW in Cape Giradeau, MO! Please say hello to them if you go to the Falling Leaf Rally. They've been friendly, empathetic, available, and knowledgeable. Thanks...

[SIBUD]

Although the tech isn't 100% certain, he believes he fixed the problem. (I say not 100%, because he can't get the bike to act up anymore, but he's been riding it every day just to be sure).
Looks like the issue was the O2 sensor wire, which was routed incorrectly. Apparently, he's seen this issue before and there was a recall several years ago for several models affected.
My limited understanding (by phone) is that the O2 sensor wire was too close to a spark plug wire, and that this can cause all sorts if running issues, mine included. He also said these issues can present intermittently as well. The good news is that this will hardly cost me anything, and the better news is that my bike may be fixed, and I can ride it to the Falling Leaf Rally! :dance
Although I'll still have to pony up for the tire change, spark plugs (autolite), and the slight adjustment to the TPS. But, I can live with that.
I can't say enough about Grassroots BMW in Cape Giradeau, MO! Please say hello to them if you go to the Falling Leaf Rally. They've been friendly, empathetic, available, and knowledgeable. Thanks...

Congrats.

Herb and Reno run a great shop at Grass Roots.

Hope to see you at Falling Leaf.

I will be up on the hill on a red 97 rt and an yellow eureka tent. Look for the rowdies from Iowa, I will be hanging with them.

[alien_hitchhiker]

Looks like the issue was the O2 sensor wire, which was routed incorrectly. Apparently, he's seen this issue before and there was a recall several years ago for several models affected.



Thanks for posting the follow-up.

This is interesting. There is always something new to learn.

(I've noticed that it's so much easier when it's someone else's misery :bolt )