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R1100S idles way too slow and tries to stall when hot - Why?
- Thread starter montliz
- Start date
I'm neither pro nor con about K+N filters. I've used them on several other bikes and I think they're a great product and that they do seem to increase breathing and performance. That said, I probably wouldn't have installed one on this S, but the previous owner had already made the switch, so I guess I'll leave it in place. I appreciate their quality and design and plus it's not at all dusty around here, so the K+N doesn't even make the chart of my S worries.
@ Rad, thanks for the questions. My bike did have some minor surging which was more irritating than anything else, but it basically just went away when I installed the AF-xied. Great product! Plus now I'm in the process of cleaning out and re-syncing my throttle bodies after they gave up trying to idle last weekend. After a lot of research and the wonderful help and suggestions from the good folks on this forum, I think I'm on top of that situation and I expect a full recovery and even better performance when I finish the job. Thanks MOA!
BTW, my 2000 S doesn't have stick coils, but if it did they would definitely be suspect.
Thanks again,
Johnny
@ Rad, thanks for the questions. My bike did have some minor surging which was more irritating than anything else, but it basically just went away when I installed the AF-xied. Great product! Plus now I'm in the process of cleaning out and re-syncing my throttle bodies after they gave up trying to idle last weekend. After a lot of research and the wonderful help and suggestions from the good folks on this forum, I think I'm on top of that situation and I expect a full recovery and even better performance when I finish the job. Thanks MOA!
BTW, my 2000 S doesn't have stick coils, but if it did they would definitely be suspect.
Thanks again,
Johnny
roger 04 rt
New member
Johnny, When you get to syncing your throttle bodies, have a read through this: BMW Repair Manual Throttle Body Synchroization Procedure.
It's fairly detailed but will produce good balance and correct cable tension. Roger
It's fairly detailed but will produce good balance and correct cable tension. Roger
rad
Retired from riding
Duh.....oh ya, I had a 99' the ninth S produced, serial number 00000 and more zeros followed by a lonely little number 9. I also had a twin spark 04 S, of course the 04 was the stick coil critter.
Glad you are getting it sorted out, I enjoyed my S's.
Quick tip, just between me and you, watch out for that BC1100S guy.
Thanks for the link, Roger.
That's better and much more detailed than the one I've been using. I will use it fer sure. We appreciate your help.
Johnny
AntonLargiader
Active member
I don't follow you. If squeezing the clutch is one way to make the idle return to normal, and the clanking goes away, it sounds like they are very related. Am I misunderstanding your description?
pauls1150
MOA #24991, south of Los Angeles
Agreed - When you pull in the clutch lever, you disconnect the trans from the engine... hopefully.
NORMALLY, yes the trans noise (as several of those shafts & gears spin, even in Neutral) will go down a bit when the clutch is pulled. (Noise is why I mentioned the left cam chain tensioner earlier; a worthwhile upgrade regardless.)
But if the RPM actually changes when you pull the clutch, then you've got some drag there - either the clutch really isn't fully disengaging, or a bushing (WAG) in the trans might be narfed. Lower possibility: the trans oil is extremely old or just the wrong stuff.
NORMALLY, yes the trans noise (as several of those shafts & gears spin, even in Neutral) will go down a bit when the clutch is pulled. (Noise is why I mentioned the left cam chain tensioner earlier; a worthwhile upgrade regardless.)
But if the RPM actually changes when you pull the clutch, then you've got some drag there - either the clutch really isn't fully disengaging, or a bushing (WAG) in the trans might be narfed. Lower possibility: the trans oil is extremely old or just the wrong stuff.
rxcrider
New member
Paging Montliz for clarity...
I read it as the noise went away but the idle speed stayed the same when the clutch was disengaged (lever pulled in). In reality, the statement wasn't particularly clear. If Anton read it right and both speed and noise are cured by disengaging the clutch, you have been chasing the wrong rabbit.
No No, sorry for the confusion; my fault for not being clear. The clutch operation had nothing to do with the idle speed, all disengaging the clutch did was cause the transmission to quiet down. I still had to use the twistgrip or "choke" lever to bring the idle speed back up. The clutch operation is fine, no problems. Sorry about that.
Also I think I've discovered the cause of the extra clanking noise. When the idle was so slow and rough the big ol' boxer was shaking so much that it caused the lower Allen bolt that holds the collar from the left exhaust pipe into the catalytic converter to contact the subframe right below it. There's not much clearance there anyway, and the subframe now has a nice Allen cap screw-shaped dent in it, like it's been hit several times. I'm thinking I may have heard that same sound on occasion when starting out in first under normal conditions. That would explain a lot. I can see why the two bolts have to be located in that 11-and-5 position; otherwise you wouldn't be able to get a wrench on the upper bolt.
In a car you'ld be looking for a broken motor mount, but I don't know if that's the case here. Maybe they're just normally a little too close for comfort. Has anyone else had this problem? Looks like my good tune-up (underway as we speak) and a little rubber cushion on the subframe right there might solve that problem. After we get running again I'll investigate further.
Gotta love a Beemer
Johnny
Also I think I've discovered the cause of the extra clanking noise. When the idle was so slow and rough the big ol' boxer was shaking so much that it caused the lower Allen bolt that holds the collar from the left exhaust pipe into the catalytic converter to contact the subframe right below it. There's not much clearance there anyway, and the subframe now has a nice Allen cap screw-shaped dent in it, like it's been hit several times. I'm thinking I may have heard that same sound on occasion when starting out in first under normal conditions. That would explain a lot. I can see why the two bolts have to be located in that 11-and-5 position; otherwise you wouldn't be able to get a wrench on the upper bolt.
In a car you'ld be looking for a broken motor mount, but I don't know if that's the case here. Maybe they're just normally a little too close for comfort. Has anyone else had this problem? Looks like my good tune-up (underway as we speak) and a little rubber cushion on the subframe right there might solve that problem. After we get running again I'll investigate further.
Gotta love a Beemer
Johnny
Annnd we're back!
Gosh I've been learning a lot of cool stuff.
Seems like a long time now, but way last year when I bought this bike I had the crazy idea that I'd be getting into a reliable, low-mileage daily rider that I could take on a trip with from time to time with no worries. HA!- As If!
Feel free to laugh if I tell you I traded a basically brand-new and totally bulletproof Honda which actually did fit that description for this excellent learning opportunity; I don't mind; I can handle it.
Little did I know that within a few months I would be able to have actual conversations with any oilhead or other modrun BMW owner and feel like at least a partially dues-paid member of the club.
I love that feeling. Not counting how many times I've had the Tupperware off and on and the special BMW tools I've made (like my custom-designed slip-knife for removing the front turn signal lenses), I've done just about every procedure short of pulling the engine and trans and replacing the clutch. (I know, I know, wait till next year...).
Anyway, I've just put the bike back together after removing and cleaning out the the throttle bodies, BBSs, passageways, and airboxes. It's back in business, and I took it out today for a little 50-mile run with a tankful of clean fuel laced with fuel injector cleaner. I think it's going to live! It idles (sort of) at @ 1000 rpm and has great throttle response, both accelerating and decelerating (since I cleaned all the gunk out from around the throttle plates). I'm going back out tomorrow, out in the country where I can run that tankful of fuel through there and see if I can improve it even more.
So, good report so far. Couple of questions: What (if anything) is the function of the BBSs other than fine-tuning the idle and carb sync?
Gosh I've been learning a lot of cool stuff.
Seems like a long time now, but way last year when I bought this bike I had the crazy idea that I'd be getting into a reliable, low-mileage daily rider that I could take on a trip with from time to time with no worries. HA!- As If!
Feel free to laugh if I tell you I traded a basically brand-new and totally bulletproof Honda which actually did fit that description for this excellent learning opportunity; I don't mind; I can handle it.
Little did I know that within a few months I would be able to have actual conversations with any oilhead or other modrun BMW owner and feel like at least a partially dues-paid member of the club.
I love that feeling. Not counting how many times I've had the Tupperware off and on and the special BMW tools I've made (like my custom-designed slip-knife for removing the front turn signal lenses), I've done just about every procedure short of pulling the engine and trans and replacing the clutch. (I know, I know, wait till next year...).
Anyway, I've just put the bike back together after removing and cleaning out the the throttle bodies, BBSs, passageways, and airboxes. It's back in business, and I took it out today for a little 50-mile run with a tankful of clean fuel laced with fuel injector cleaner. I think it's going to live! It idles (sort of) at @ 1000 rpm and has great throttle response, both accelerating and decelerating (since I cleaned all the gunk out from around the throttle plates). I'm going back out tomorrow, out in the country where I can run that tankful of fuel through there and see if I can improve it even more.
So, good report so far. Couple of questions: What (if anything) is the function of the BBSs other than fine-tuning the idle and carb sync?
And "B" ( sorry about that, premature send; it happens), what is the normal setting for the BBSs? Mine are now at 2 turns out from closed, but that may be subject to readjustment after I get my fuel injectors cleaned out. Is 2 turns in the normal range? Right now that's what lets it idle and balances both carbs on the manometer, but I don't have any previous experience with them. Hopefully back with more tomorrow.
Thanks,
Johnny
Thanks,
Johnny
pauls1150
MOA #24991, south of Los Angeles
Two turns out is easily in the "Good" range. And yes, the screw position - in conjunction with the throttle Stop screws, bearing against the tab on the pulleys - is what determines the idle speed; more air = higher speed, if and when everything is right (unless/until it's backed out too far to matter, maybe > 3 turns?). When that screw has little or no effect is an indication that there's prob'ly a junk buildup that needs cleaning out. Also note that if the O-ring on those screws cracks, that'll be another source of unmetered air flow.
Thanks Paul,
I went out yesterday and put another 60 miles on the bike and I'm seeing steady improvement. I'm still in that tankful of new fuel laced with F.I. cleaner, but I plan to finish that off later today and then refill with somewhat less cleaner added.
After my ride yesterday I re-synced the carbs and now have a setting of 1.5 on the right BBS and 2 on the left at 1100 rpms. It idles with no assist from me at 1000 but it just barely holds that engine speed and you keep wanting to run it up a little. However, it doesn't die instantly at stop lights anymore, so I'm calling that an improvement. Hopefully some more riding and conditioned fuel will contiinue to clear it up.
I could probably quick-fix it by adjusting the throttle plate stop, but it still has the factory blue paint in place so I'm holding off on that for the time being. The o-rings on the BBSs appear to be in good shape, but I'll take a closer look at them with my old people's magnifying glass today.
By the way, while I had the left carb off I went ahead and replaced the original cam chain tensioner with the new and improved version (Thanks, Rusty@Max BMW) and it made a huge difference in the engine noise at idle - Huge! Now the only outstanding noise is a little clatter from the right throttle shaft at idle. I'll put that on my to-do list.
Cheers,
Johnny
I went out yesterday and put another 60 miles on the bike and I'm seeing steady improvement. I'm still in that tankful of new fuel laced with F.I. cleaner, but I plan to finish that off later today and then refill with somewhat less cleaner added.
After my ride yesterday I re-synced the carbs and now have a setting of 1.5 on the right BBS and 2 on the left at 1100 rpms. It idles with no assist from me at 1000 but it just barely holds that engine speed and you keep wanting to run it up a little. However, it doesn't die instantly at stop lights anymore, so I'm calling that an improvement. Hopefully some more riding and conditioned fuel will contiinue to clear it up.
I could probably quick-fix it by adjusting the throttle plate stop, but it still has the factory blue paint in place so I'm holding off on that for the time being. The o-rings on the BBSs appear to be in good shape, but I'll take a closer look at them with my old people's magnifying glass today.
By the way, while I had the left carb off I went ahead and replaced the original cam chain tensioner with the new and improved version (Thanks, Rusty@Max BMW) and it made a huge difference in the engine noise at idle - Huge! Now the only outstanding noise is a little clatter from the right throttle shaft at idle. I'll put that on my to-do list.
Cheers,
Johnny
Note, Valves get looser hot. The aluminum head expands more than the steel valve. The engineers knew what they were doing.
Rod
roger 04 rt
New member
J, If you did the hot TB sync at 1100, presumably it held 1100. When does it drop RPM?
Avoid the temptation to fool with the stop-screws. I still think you're going to find another issue. R
Hey Roger,
It won't hold 1100 on its own, so I use Mr. Throttlemeister to hold it there to sync the carbs. At stoplights it will sort of idle but at an indicated 800 or 900 rpms or so, not strong at all, and the bike starts to shake and it's obvious it's trying to die, so you, the rider, immediately feather it up a little or pull up the "choke" lever to its relaxed, worn-out, halfway position and it will sit there through the light at a perfectly smooth 11-1200 rpms.
I just got home and I've run through pretty much a full tankful of clean fuel with a double dose of FI cleaner, 130 miles, and I replaced it with a tankful of Chevron 93 octane and brought it home. The bike runs great out on the back roads and has astonishing and scary high-speed performance, just as it should - it just won't idle very well without a little help from a friend.
The engine sounds great now that I've replaced the cam chain tension adjuster, and it's super-smooth and even and powerful, but it doesn't idle on its own, and I'm holding off on breaking the blue paint on the throttle stop even though that would (sort of) resolve the symptoms.
I'm thinking that the next step might be to have the fuel injectors checked. Our Houston BMW dealer, Gulf Coast BMW, has a fuel injector service they use who will test and clean the FIs, but they're 50 not-fun miles away and that would involve a lot of downtime and expense. A much easier solution would be to buy and install new FIs, but (without looking up the price) I'm guessing that might involve the transfer of a few dollars.
Whaddya think?
Johnny
It won't hold 1100 on its own, so I use Mr. Throttlemeister to hold it there to sync the carbs. At stoplights it will sort of idle but at an indicated 800 or 900 rpms or so, not strong at all, and the bike starts to shake and it's obvious it's trying to die, so you, the rider, immediately feather it up a little or pull up the "choke" lever to its relaxed, worn-out, halfway position and it will sit there through the light at a perfectly smooth 11-1200 rpms.
I just got home and I've run through pretty much a full tankful of clean fuel with a double dose of FI cleaner, 130 miles, and I replaced it with a tankful of Chevron 93 octane and brought it home. The bike runs great out on the back roads and has astonishing and scary high-speed performance, just as it should - it just won't idle very well without a little help from a friend.
The engine sounds great now that I've replaced the cam chain tension adjuster, and it's super-smooth and even and powerful, but it doesn't idle on its own, and I'm holding off on breaking the blue paint on the throttle stop even though that would (sort of) resolve the symptoms.
I'm thinking that the next step might be to have the fuel injectors checked. Our Houston BMW dealer, Gulf Coast BMW, has a fuel injector service they use who will test and clean the FIs, but they're 50 not-fun miles away and that would involve a lot of downtime and expense. A much easier solution would be to buy and install new FIs, but (without looking up the price) I'm guessing that might involve the transfer of a few dollars.
Whaddya think?
Johnny
pauls1150
MOA #24991, south of Los Angeles
Yeah, Rod, there's been a lot of debate over valve clearances for a long long time...
Some people don't see the whole picture: there's more involved than just a valve stem or a particular part of the head.
And I've seen many bikes that just won't idle through downtown, or spin up freely, until the valves get more slack.
Your mileage may vary... Everybody will use what works for them. There is ample proof that sometimes the engineers goof up too - HES triggers, cam chain tensioners (on several models), rear drives (on several models), U-joints (on several models), etc...
Johnny, there's nothing holy about the friggin' blue paint. If you have and can use a good DVM to check & adjust the TPS (several on-line articles are available, here, on the R.A. tech pages, and in the ADVRider pages), and you know how to balance the throttle bodies, there is nothing to be lost by just doing it. Heck, it may even be as simple as backing out the BBS's another eighth- or quarter-turn each. But Roger is right too in that there's no substitute for the scientific method of seeing exactly what's happening in there.
Some people don't see the whole picture: there's more involved than just a valve stem or a particular part of the head.
And I've seen many bikes that just won't idle through downtown, or spin up freely, until the valves get more slack.
Your mileage may vary... Everybody will use what works for them. There is ample proof that sometimes the engineers goof up too - HES triggers, cam chain tensioners (on several models), rear drives (on several models), U-joints (on several models), etc...
Johnny, there's nothing holy about the friggin' blue paint. If you have and can use a good DVM to check & adjust the TPS (several on-line articles are available, here, on the R.A. tech pages, and in the ADVRider pages), and you know how to balance the throttle bodies, there is nothing to be lost by just doing it. Heck, it may even be as simple as backing out the BBS's another eighth- or quarter-turn each. But Roger is right too in that there's no substitute for the scientific method of seeing exactly what's happening in there.
roger 04 rt
New member
Johnny, Don't touch the throttle stop screws yet! You could easily mask the true problem. I've rethought my suggestions for how you could approach this.
It could be your fuel injectors are the problem. Maybe one or the other leaks and it's bogging down at idle. That could progressively richen the mixture.
The other possibility is that the Motronic is calculating the wrong amount of fuel due to a faulty sensor (TPS comes to mind) and closed loop using the O2 won't add enough fuel.
As I mentioned earlier, if you could borrow a GS-911 you would know immediately what the sensors are telling the Motronic and importantly, it would report the lambda sensor voltage which would let us know if your bike was getting progressively richer or leaner at idle.
Without a GS-911 here are three tests you can make:
1) What is the O2 sensor voltage at idle. With your AF-XIED disconnected and the O2 sensor connected normally, measure between the voltage between the grey wire and black wire. Connect the + lead of your DVM to the Black wire. If the voltage sinks and stays below 450 mV then your bike is running too lean and you may have a sensor issue. If the voltage rises and stays above 450 mV your bike is running too rich. If it bounces around between 200 mV and 700 mV then your bike is running as it should in closed loop.
2) Carefully pull one injector at a time and leave it connected to the fuel distributor. Cycle the key 4 or 5 times, let it sit for a minute or two and see if any fuel is dripping.
3) Watch your TPS voltage by measuring between its pins 1 and 4. The voltage should be around 340 mV, but importantly, it should stay wherever it is. If it sinks or rises with your hand off the throttle, that's a problem.
RB
It could be your fuel injectors are the problem. Maybe one or the other leaks and it's bogging down at idle. That could progressively richen the mixture.
The other possibility is that the Motronic is calculating the wrong amount of fuel due to a faulty sensor (TPS comes to mind) and closed loop using the O2 won't add enough fuel.
As I mentioned earlier, if you could borrow a GS-911 you would know immediately what the sensors are telling the Motronic and importantly, it would report the lambda sensor voltage which would let us know if your bike was getting progressively richer or leaner at idle.
Without a GS-911 here are three tests you can make:
1) What is the O2 sensor voltage at idle. With your AF-XIED disconnected and the O2 sensor connected normally, measure between the voltage between the grey wire and black wire. Connect the + lead of your DVM to the Black wire. If the voltage sinks and stays below 450 mV then your bike is running too lean and you may have a sensor issue. If the voltage rises and stays above 450 mV your bike is running too rich. If it bounces around between 200 mV and 700 mV then your bike is running as it should in closed loop.
2) Carefully pull one injector at a time and leave it connected to the fuel distributor. Cycle the key 4 or 5 times, let it sit for a minute or two and see if any fuel is dripping.
3) Watch your TPS voltage by measuring between its pins 1 and 4. The voltage should be around 340 mV, but importantly, it should stay wherever it is. If it sinks or rises with your hand off the throttle, that's a problem.
RB
