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Thread: 2002 K1200RS High Idle

  1. #16
    Join Date
    Nov 2004
    Arizona, USA

    What next?

    Today I did a Motronic unit pin clean. I pulled the unit off the back of the “wiring box”, cleaned the pins on the Motornic and on the back of the box. After removing the full 'wiring box' cover, I played with the pins leading into the Motronic, no indication of a loose or broken pin.

    I found the two wires that run from the Engine Temperature Sensor to the pins in the Motronic connector – a purple wire and a brown/yellow wire. With the Motronic removed there is continuity between the Engine Temperature Sensor connector and the Motronic pin connector. The Engine Temperature Sensor signal is getting to the Motronic.

    Before I put everything back together I did a GS911 TPS set. TPS set correctly.

    I made sure the throttle wasn’t hanging up and there was about ¼ inch play in the cruise control cable. All was good to the best of my ability.

    Gas tank on…and…Rotti idled at 1,500 and did not drop as the temperature reached 180 f.

    A scan of the Engine Temperature Sensor with my IR gun showed the same temperature +- 1 f. The Ambient Air Temperature sensor reading and my IR reading were also within +- 1 f.

    Running the Realtime Values in the GS911 shows the TPS angle, engine temperature, etc. The TPS angle never drops from initial start, engine temperature indicated at about 90 f, to fans on at about 218 f.

    Time to have Iron Horse Motorcycles check the Motronic unit.

    Or…do I find a used unit. There are several used Motornics available. Turns out there are several iterations and the units ending in 296 are the preferred. Rotti has the 477 version second to the 296.

    Any thoughts?
    Last edited by mehrten; 08-02-2021 at 09:14 PM.

  2. #17
    Join Date
    Nov 2004
    Arizona, USA

    Problem may be solved...

    The used Engine Temperature Sensor (ETS) came in Thursday afternoon.

    I connected the used ETS to Rotti, leaving the original ETS installed but disconnected.

    The bike started with a 1,300 to 1,400 rpm idle. I used a heat gun on the sensor tip and in less than a minute the bike dropped into a 1,000 rpm idle!

    Later today I will begin the process of installing the used ETS. The ETS on the K1200 bricks is buried behind the coils on the right side of the cylinder head.

    I’m not going to call Rotti cured until the used ETS is install and I fire her up.

    Fingers and toes crossed…

  3. #18
    Join Date
    Nov 2004
    Arizona, USA


    After getting such a positive result with the used Engine Temperature Sensor connected to Rotti, what a disappointment that after installing the used ETS the idle did not drop.

    The only difference was when I tested the used ETS it was not grounded to the bike, i.e. it was not screwed into the engine and thus not grounded. Could that be a problem???

    Any way...

    A used Motronic unit finally showed up and it was a no go right off.

    When I installed it and turned on the ignition the fans immediately came on.

    I read where that was a symptom of a bad ETS. I swapped the ETS back to my original one though not installed/screwed into the engine.

    Same, fans came on with ignition on. Could I have two bad ETSs?

    Reinstalled my original Motronic unit, turned on the key - fans did not come on.

    Did the ETS swap again, no problem - fans did not come on with ignition on.

    I may have more than one bad piece of the puzzle that has me stumped.

    Time to let the pros work on her.

    Question: Can the Motronic Unit be tested off the bike?


  4. #19
    Join Date
    Nov 2004
    Arizona, USA

    Time for the Pros to take a look...

    I'm dropping Rotti off at Iron Horse Motorcycles in Tucson today.

    After much testing and swapping of parts I was not able to solve the problem.

    I have been concentrating on the TPS, TVA and the ETS with a mixed bag of results.

    Testing the Motronic unit is above my paygrade.

    Time to let the Pros in.

    I will post the results.

    Thanks to all for the help.

    P.S. Thanks to the Presidents and Gurus on the IBMW Riders and the IBMW Tech lists for their help as well.

  5. #20
    Join Date
    Nov 2004
    Arizona, USA

    What's happening...

    I dropped Rotti off at Iron Horse on Wednesday the 18th of August.

    Before I left for Tucson, an 80~90 mile ride to Iron Horse, I removed the Throttle Valve Actuator.

    Rotti started a bit hesitantly, though with a bit of throttle I could keep her idling around 1,000 rpm.

    Once warmed up she idled at about 900~950 rpm which was good enough to keep everything running and charging.

    On the way up to Tucson via 1-10 Rotti ran as good as she always has. I hit 100 mph easily (and a bit more).

    Coming into town I had no problems at stop signs/lights with Rotti idling.

    At the shop I spent about an hour explaining to the Master Tech what I'd done to Rotti.

    Turns out he went to the MOA forum and read these write ups.

    Between the two of us we came up two more areas to check.

    I mounted a rear license plate frame with two sets of LEDs connected to a Signal Dynamics BackUP module.

    Did I not connect the grounds right?

    In June 2021 I did a full brake fluid bleed that requires disconnecting the ABS pump.

    Did I not get the ABS connector back on correctly?

    Maybe the brain is getting a keep-the-rpms-up because the ABS is sending an on signal?

    The Master Tech already did a voltage regulator check and found no problems.

    More to come as other tests and diagnostics are preformed.

  6. #21
    Join Date
    Nov 2004
    Arizona, USA


    And it was…….a massive air leak!!!

    Here’s what happened.

    It has been my impression that the top rubber pieces on the throttle bodies, I’ll call them “snorkels”, were to remain on the throttle bodies. Every time I pulled the intake muffler off I left the rubber “snorkels” attached to the throttle bodies.

    Not right.

    The rubber intake “snorkels” should have been disconnected from the throttle bodies and left inserted into the intake muffler.

    Keep in mind that I have had the intake muffler off more than a few times since we acquired Rotti back in 2012. Each time the “snorkels” were, I’ll say, long enough to push back into the intake muffler to make a sufficient seal.

    When I did the brake bleed back in Jun of 2021 I did pull the tank and intake muffler off the bike to do some clean up and to keep any brake fluid from dripping on any surfaces. When I replaced the intake muffler this was the last straw so to speak, the “snorkels” had become so pushed down on the throttle bodies that they were no longer long enough to push into the intake muffler and create a seal.

    The result…a massive air leak.

    Both I and the Tech did an air leak test or two. Both of us sprayed the flammable fluid at the throttle bodies and the rubber manifold sealing the throttle bodies to the cylinder head. Both of us got negative results so a possible air leak was shelved.

    While doing the nth test start, the shop Tech noticed the air muffler was very loose on top of the throttle bodies. That’s when he discovered that the “snorkels” were not sealing properly into the intake muffler. An air leak test with the flammable spray pointed towards the “snorkels” and the intake muffler told the story…a massive air leak.

    All went back together with the “snorkels” properly seated in the intake muffler and Rotti began to correct itself as the Motronic learned the new air flow. By the third start she idled at the factory 1,050 rpms.

    So…after a huge amount of testing and replacing and testing and replacing it was nothing more than an air leak.

    This has been an experience, for sure, though I’ve learned a lot in both how Rotti works and how to diagnose problems she may develop.

    I should have Rotti home by next weekend, the 18th of September. I’m considering throwing a “Welcome Home Rotti!” party.

    Thanks to all who commented and provided moral support. It was appreciated.

    And super thanks to Markus and Iron Horse Motorcycles in Tucson, AZ for finally sorting it out.

    Deryle & Wanda Mehrten
    Sierra Vista, AZ USA

  7. #22
    Fortis Fortuna Adiuvat Omega Man's Avatar
    Join Date
    Jan 2010

    "You can do good or you can do well. Sooner or later they make you choose." MI5
    Mod Squad
    2009 F800GS 1994 TW200

  8. #23
    Debbie's Servant Lee's Avatar
    Join Date
    May 2003
    SW Iowa
    Thanks for the update.
    2016 R1200RS
    MOA # 30878
    Past BMW Bikes: 2011 K1300S, 2003 K1200RS, 1991 K75S, 1987 K75T, 1984 R100RT

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