Pulsating at idle? - BMW Luxury Touring Community
 
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post #1 of 8 Old Oct 11th, 2008, 8:52 am Thread Starter
 
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Pulsating at idle?

Advice needed! Ref: 2006 K12LT with 36K. (36K maintanance completed by Mac's three weeks ago)

Yesterday I went to Mac's Cycle in Clarkston WA for a warranty replacement for the powered centerstand. I bought a new Exide battery for them to install. When the work was completed, Ivan the mechanic was somewhat puzzled why the engine was pusating at idle (400-750rpms). Anyway, I rode the LT 120 miles home that afternoon. The bike now sometimes dies at idle or still pulsates.

Question: When the battery was replaced could the computer settings have something to do with the rough idling problem. All else is normal.

Thanks in advance!

AL
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post #2 of 8 Old Oct 11th, 2008, 9:27 am
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Re: Pulsating at idle?

With my limited knowledge, however many hours spent working on this machine and I too had issue with stalling.......the Motronic needs to be reset after the battery install. A matter of turning the key on, pull throttle to full position and back to zero 3-4 times, turn off the key and that should be it. I also believe it was supposed to reset itself once it was ridden for a while. Don't know more than that, so may want to do a search on the Motronic reset procedure.

You would think the dealer would have done that however. May want to call and ask.

Hope that helps.
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post #3 of 8 Old Oct 11th, 2008, 9:32 am
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Cool Re: Pulsating at idle?

Not sure if it is the same thing Al, but if your "pulsating" could also be that the engine is searching for the correct idle RPM. This is most often a symptom of a vacuum leak. And the most common cause is that one of the vacuum hoses has been knocked off of the throttle bodies near the fuel rail. It is very easy to accidently knock or bump these off during maintenance, and someone would have been in that area during a 36K, so it can't hurt to check them. If any of the four hoses has been knocked off the engine will "search" up & down trying to find the correct idle speed. It is often quite a bit higher in the RPM's than what you describe here, but it is just an idea.

Just thinking out loud here.

HTH,

John

John & Marilyn Fisher
'00 K1200LTC "Katie"
'95 Triumph "Tigger"
'12 Triumph 800XC "Tigger II" (RIP)
'12 Triumph 1200 Explorer "Shadow Tigger"
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post #4 of 8 Old Oct 11th, 2008, 10:02 am
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Re: Pulsating at idle?

I too would suspect a vacuum leak or a pinched vacuum hose. The motronic will relearn the settings on its' own even if you don't perform the TPS reset, especially if you have ridden 120 miles. JM2CW

Res ipsa loquitur, sed quid in infernos dicet?

Alan Stuber
2003 K1200 LTC Titan Silver
Austin, Texas



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post #5 of 8 Old Oct 12th, 2008, 7:22 am Thread Starter
 
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Re: Pulsating at idle?

Thank you all for your suggestions. I will follow your advice. Just another reason I love Beemer Riders.

v/r

AL
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post #6 of 8 Old Oct 12th, 2008, 9:17 am
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Smile Re: Pulsating at idle?

My 03 LT had been pulsating for some time. Not real bad but noticable. When I had some work done at the dealership the mechanic noticed that the inlet tubes which are plastic had cracks in them. He replaced all 4 and it solved the problem.
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post #7 of 8 Old Oct 12th, 2008, 12:12 pm
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Re: Pulsating at idle?

I had rough idling around 1500 to 2000 RPM after replacing the battery. The engine management needs to relearn the fuel type / ignition parameters etc before it will settle down. Mine took about two days to return to normal.

Just pussin' through.
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post #8 of 8 Old Oct 12th, 2008, 3:38 pm
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Re: Pulsating at idle?

Quote:
Originally Posted by JDW
My 03 LT had been pulsating for some time. Not real bad but noticable. When I had some work done at the dealership the mechanic noticed that the inlet tubes which are plastic had cracks in them. He replaced all 4 and it solved the problem.
The inlet tubes on top of the throttle bodies cannot cause this problem. The only thing bad that can happen if these are cracked is intake of dirty air to the engine, as it bypasses the filter.

Only air leaks BELOW the throttle butterfly valves, such as the O-rings on the bottom of the throttle bodies, O-rings for the injectors, or the vacuum lines for the emission control system (cannister) can cause the idle problems.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

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EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
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