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Dropped an 02 motor into my 99LT and while it runs fairly (but not perfectly) smooth at anything over 2500 rpm, it will not idle well, runs very rough and knocks like a can of paint was left in the motor.

I was "playing" with it (as my wife says) earlier and pulled the vacum line off of the vacum module (for lack of a proper identification) and it smoothed out, a lot. Just what is this little canister that slips on the plastic spade, just out board of the throttle bodies?????

My K100 doesnt have it, the manual shows it, but doesnt i.d. it.

I'm trying to get this bike on the road for the RA National. Dealer says they cant look at it for a month!

While I am familiar with my 85, this 99 is "high tech" for this mechanic and I am still learning. Any suggestions?
 

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First thing you need to try is reset the motronic. This can be accomplished by pulling fuse # 4 from the rightmost fuse box under the seat and leaving it out for several hours (I usually do this overnight). After you plug the fuse back in turn the ignition ON but DO NOT start the engine!!! Roll the throttle all the way and release, then do it one more time. Turn the ignition OFF. Turn the ignition back ON and this time start the engine. The Motronic will begin "learning" your throttle usage. This may cure some or maybe most of your issue.
Regardless it is a step you need to perform, so you might as well do it and test drive the bike.
 

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Resetting the motronic certainly wouldn't hurt anything, but I would tend to think the symptoms you are experiencing would more likely be a vacuum leak. Make sure you haven't left a vacuum line loose.
 

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this is a new one for me, i bought the bike used, do i need to reset the motronic, and will i benefit from doing so...i am interpreting this as the motronic setting the throttle response to the riders habits...is that correct ? :confused:
 

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Dean_BMW said:
Resetting the motronic certainly wouldn't hurt anything, but I would tend to think the symptoms you are experiencing would more likely be a vacuum leak. Make sure you haven't left a vacuum line loose.
Also recheck all clamps on the throttle bodies if these are loose your bike will run poor.
 

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Discussion Starter #7
running rough

I have so far: checked all cable adjustments, reset the system, double & triple checked for vacuum leaks (my first thoughts) checked the electrical system for physical damage and proper connections and proper charging and battery condition.

The rattle I am hearing sounds like it is the "normal" alternator drive rattle that I have read about in these threads, since it goes away at higher rpm, and gets a little better under electrical load. I can live with it, though the original motor ran smooth and quiet even with 3 broken pistons. Amazing.

What conditions would have to exsist to allow the motor to run smoother with a vacuum leak, than with the ports plugged? I've been scratching my head over this one for over a month now.

The motor runs pretty good over 2500 rpm. Two up, the bike got 55 mpg on a recent trip of 700 miles, so its not like it is a huge problem.

Oh, and maybe related, maybe not, the cruise control has not worked since I swapped motors. The system check works fine, but no go on the cruise. I cant help but think it is related. Starts right up too, just doesnt settle into a nice smooth idle as it once did.

Thanks for the info on the roll over valve. I will unplug and re
move it. And keep scratching my head.
 

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WD40 instead of propane

I use a plumbers propane torch to check for air leaks. (unlit of course)
If the thing is sucking air the propane will speed up the engine.
Rock



WD40 works just as well and is safer. Just spray a light fog at any potential vacuum leak area and the engine will start running differently as soon as the WD40 gets into the intake system.
 

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Interesting. Pastor Jack has a similar problem recently, searching for vacuum leaks had him in fits. See this thread: http://www.bmwlt.com/forums/showthread.php?t=21412&page=3&pp=10&highlight=vacuum+leakHe reset the Motonic using the throttle procedure (see Zippy-gg's post above), but that did not solve the problem. Finally he took the bike out and just ran it for an hour on the roads, and that did solve the problem. I don't know if you did your 700 mile trip before or after using the throttle reset procedure, but if you have not run the bike for any length of time since resetting the Motronic, give that a try.
The interesting thing here is that the idle smooths out when you take off the hose from the pulse valve. As others have said, that hose normally is connected to the charcoal cannister. The pulse valve is operated by a solenoid that keeps it shut until the engine reaches a pre-set RPM (I'm cribbing from a post that David Shealey contributed to the thread above). It opens up to create vacuum in the hose to scavenge gas vapor from the charcoal cannister (in pulses?). Although I don't understand why, I know that some engines have run rough at idle when the hose has been pinched under the gas tank. In your case, it may be that the hose is pinched, that it has a hole in it somewhere (there is a connector farther back), or that your cannister is blocked. The common cure for these and other woes caused by the cannister is a "cannisterectomy," a fairly simple procedure that includes blocking off that hose, removing the cannister, and re-routing the front portion of the other hose that goes to the cannister from the gas tank. Procedures for doing this are in the Hall of Wisdom, or do a search on "cannisterectomy."
So, I'd try, in order, resetting the motronic with the throttle procedure, riding the bike for at least a half hour, both town roads and highway, and doing a cannisterectomy. Good luck.
 

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Wolfgang said:
I use a plumbers propane torch to check for air leaks. (unlit of course)
If the thing is sucking air the propane will speed up the engine.
Rock



WD40 works just as well and is safer. Just spray a light fog at any potential vacuum leak area and the engine will start running differently as soon as the WD40 gets into the intake system.
My bike gets dirty enough without me spraying crazy glue for dust on it.
I used it one time on the Chopper Shop's soda machine out by the road (to clean the road grime out, displace water from the coin mechanism etc.) What a huge mistake that was, I had to take the coin mech out of the machine and run it through the parts washer a couple days later :eek: .
But you are right it will work, I use it as starting fluid on stuff, not sure about the safer part they are both flammable.
Rock
 

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skaboots said:
this is a new one for me, i bought the bike used, do i need to reset the motronic, and will i benefit from doing so...i am interpreting this as the motronic setting the throttle response to the riders habits...is that correct ? :confused:
No, it is not about rider's habits. The Engine Control Module needs to know the signal levels corresponding to full-close and full-open throttle in order to be able to determine the actual position later on.

These signals vary from bike to bike and they need to be memorized by ECM.

Re-doing the procedure will not hurt anything in your situation, but most likely will not change anything, either.
 

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Discussion Starter #13
no better

was said:
Interesting. Pastor Jack has a similar problem recently, searching for vacuum leaks had him in fits. See this thread: http://www.bmwlt.com/forums/showthread.php?t=21412&page=3&pp=10&highlight=vacuum+leakHe reset the Motonic using the throttle procedure (see Zippy-gg's post above), but that did not solve the problem. Finally he took the bike out and just ran it for an hour on the roads, and that did solve the problem. I don't know if you did your 700 mile trip before or after using the throttle reset procedure, but if you have not run the bike for any length of time since resetting the Motronic, give that a try.
The interesting thing here is that the idle smooths out when you take off the hose from the pulse valve. As others have said, that hose normally is connected to the charcoal cannister. The pulse valve is operated by a solenoid that keeps it shut until the engine reaches a pre-set RPM (I'm cribbing from a post that David Shealey contributed to the thread above). It opens up to create vacuum in the hose to scavenge gas vapor from the charcoal cannister (in pulses?). Although I don't understand why, I know that some engines have run rough at idle when the hose has been pinched under the gas tank. In your case, it may be that the hose is pinched, that it has a hole in it somewhere (there is a connector farther back), or that your cannister is blocked. The common cure for these and other woes caused by the cannister is a "cannisterectomy," a fairly simple procedure that includes blocking off that hose, removing the cannister, and re-routing the front portion of the other hose that goes to the cannister from the gas tank. Procedures for doing this are in the Hall of Wisdom, or do a search on "cannisterectomy."
So, I'd try, in order, resetting the motronic with the throttle procedure, riding the bike for at least a half hour, both town roads and highway, and doing a cannisterectomy. Good luck.
Ok, did everything. The bike still runs good WITH the hose disconnected and sucking air. Plug the ports and runs like garbage. Completely backward from what it should be doing. I am about ready to route this line to the filtered side of the air box and let it draw air from there. This problem doesnt make much since to me, but a lot of things on the LT are like that. Nice bike, but I think they paid the engineers by the level of complication vs the level of effecient engineering. Any other suggestions out there?
 

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Before you punch a hole in the the air box ( :) ), I'm starting to think that you must be running very rich at idle (introducing air thru the pulse valve improves idle), and maybe lean at speed (55 MPG 2-up). Have you checked the O2 sensor? One guy had a cut in the wire to the O2 sensor and it produced very poor idle. (The dealer fixed it by replacing the O2 sensor and wiring, when the guy could have just spliced and soldered in new wire.) I don't know of a procedure for checking the O2 sensor, but at least check the wire to it.
 

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kbikeusr said:
Dropped an 02 motor into my 99LT and while it runs fairly (but not perfectly) smooth at anything over 2500 rpm, it will not idle well, runs very rough and knocks like a can of paint was left in the motor.

I was "playing" with it (as my wife says) earlier and pulled the vacum line off of the vacum module (for lack of a proper identification) and it smoothed out, a lot. Just what is this little canister that slips on the plastic spade, just out board of the throttle bodies?????

My K100 doesnt have it, the manual shows it, but doesnt i.d. it.

I'm trying to get this bike on the road for the RA National. Dealer says they cant look at it for a month!

While I am familiar with my 85, this 99 is "high tech" for this mechanic and I am still learning. Any suggestions?
Did you swap in the 02 Motronic as well? I'd wager that the 99 Motronic isnt compatible with the newer motor.
 

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Discussion Starter #17
02 motor

Dean_BMW said:
Is there any difference in the way it runs when it is cold than when it is warmed up?
No, did not swap the motronic. local dealer said no problem dropping in the 02 motor in the 99. was told the part numbers were still the same on 99 vs 02, so I didnt worry about it.

I did check the o2 sensor (at least I checked its physical condition) and it looks ok.

The bike runs a little better warmed up, but not much.

I was astonished with the 55 mpg, two up.... but this was with my wife who does not like speed. I ran it really easy, probably didnt hit over 70 with it the entire trip, lot of 55 mph roads too. The bike ran pretty cool too, never reaching the halfway point on the heat gage, which seems rare compared to the other LT's I have ridden.

Wouldnt a lean condition at cruising speeds run hot?
 

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The reason I asked that is because most engine computers do not rely on sensors to run the engine during warm up. I don't really know much about the Motronic, but I would imagine it has a set routine that it uses to run the engine while it is cold. If you have the same symptom both hot or cold, I think you can rule out temperature sensors and probably the oxygen sensor.

I tend to think you still have a leak around one of your throttle bodies or maybe a loose vacuum line if running the bike on a longer trip did not solve your issues after the motronic reset.

BTW, have you checked the fuel rail pressure by chance?
 

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Now that I think about it, I guess the fuel rail question was kind of dumb. If you are getting enough fuel to run down the road at 70 mph, I doubt that the fuel pressure is your problem.
 

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kbikeusr said:
Wouldnt a lean condition at cruising speeds run hot?
Yes, but it was the only thing I could think of for 55 MPG 2 up. I can't come close to that 1-up.

I'm afraid I'm out of ideas, Gene. It may be time to get it hooked up to a computer at the dealer's, see if that tells you anything. Good luck.
 
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