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Thread: 2002 K1200RS High Idle

  1. #1
    Mehrten
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    2002 K1200RS High Idle

    Recently our 2002 K1200RS started idling high, around 1,500 – 1,600 rpm vs a factory setting of 1,050. I removed all the body work and the gas tank, and examined the engine vent hose that connects to the back of the throttle bodies. There’s been an oil smell when Rotti our 2002 K1200RS gets hot and I suspected the vent hose had rotted out, causing an air leak.

    The vent hose was rotted and there was oil on the top of the engine. I replaced the hose which required pulling the throttle bodies off. After replacing the hose and putting her back together, unfortunately Rotti continued to idle high. I disconnected the battery, waited a day, then connected the battery and did the three-times-open-and-close throttle dance. No luck, she still idled at 1,500 plus.

    I connected our Wi-Fi GS911 and got repeated errors that the controller could not be read. Had Rotti’s brain gone bad? I pulled out our older GS911 and it connected to the bike no problem. Not sure why the Wi-Fi version GS911 didn’t work.

    Once again I removed all the body work and the throttle bodies and did the GS911 set routine for the Throttle Position Sensor (TPS), BMW calls it a Throttle Valve Switch. I set the green bar dead in the center. After testing it several times, I mounted the Throttle Actuator (TVA) as per the GS911 procedure. The GS911 reported a faulty TVA. I disconnected the battery, waited an hour or so and did another throttle dance. The TPS setting procedure again reported a TVA problem. I put her all back together and fired her up. No change…still a 1,500 to 1,600 idle.

    After several warm ups and a ride around the block, I did another body strip and throttle body removal and ran the GS911 TPS setting. I made sure the TPS was dead in the center, completed the procedure and again the GS911 reported a TVA problem.

    Searching the web I found a TPS testing procedure pdf file and a TVA testing procedure pdf file. The TPS pdf file stated a 1600 to 900 ohm sweep on pins 1-2 and 1120 to 1870 ohm sweep on pins 2-3 are the norms. Rotti’s TPS 1-2 pin sweep was 1540 to 810, about 60 ohms low on the high side and about 90 ohms low on the low side. Rotti’s pin 2-3 sweep was 1110 to 1550, very close on the WOT side but not so good on the closed throttle side – 300 low. There were no obvious jumps or spikes during the opening and closing of the throttle.

    The TVA is basically a small motor that pushes against the throttle arm and will increase or decrease the engine’s rpm as needed. I did the tests per the TVA testing procedure pdf file using a 9 volt battery. After several tries Rotti’s TVA elongated to 43 mm and shortened to 35 mm, very close to the parameters the test procedures called for – 44 to 36. Pin 3 to 4 is basically an off switch operated by pressure on the tip of the TVA. No problem there.

    Note: Search the web for “BMW K1200LT/K1200RS Testing a Throttle Position Sensor (also called TPS)” and “BMW K1200LT/K1200RS Throttle Valve Actuator (also called TVA or Idle-Control Motor)” for the pdf files.

    Maybe Rotti’s brain wasn’t getting a good reading from the engine temperature sensor. I pulled the lead to the engine temperature sensor and tested it as Rotti warmed up and cooled down. I took five readings: 75 f = 1.000; 100 f = .900; 140 f = .590; 190 f = .256; and 200 f = .200. The readings were consistent, rising and falling as the engine warmed and cooled. Note that when the engine temperature sensor was unplugged both of the fans came on, and both fans came on a 218 f.

    Each of the major players in the throttle opening and closing system tested relatively OK, only the 2-3 pin reading on the TPS’s low side showed any real difference. I did several manual settings of the TVA using a 9 volt battery then mounting it on the bike and not plugging it in. I found that at 39 mm extended Rotti idled at 1,500; at 37 mm she dropped into the bottom line 800 rpm idle; and at 38 mm she idled at 1,000 rpm. A very small increase/decrease made quite a difference. I sprayed water on the throttle bodies while the bike was running with no change in idle speed either at the 800 rpm idle or the 1,500 rpm idle.

    Before I drop several hundred dollars on a TPS and/or a TVA are there other areas I should test? Anyone with a similar K1200RS high idle problem that was resolved? How?

    Appreciate the help.

  2. #2
    Registered User GTRider's Avatar
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    The WiFi version of GS-911 will read the ECU on your bike if connected via USB to a PC, but is unable to read that vintage of ECU when connected WiFi to an iOS device. It’s a known issue that the mfgr is working on.

    Did the initial idle increase come on suddenly or gradually? And does the bike have cruise control installed? I’m wondering if you have a cable unseated or near failure and hanging up. If so, your throttle valve switch would not be controlling idle speed.

    Best,
    DeVern
    DGerber
    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
    BMWMOA#52184, AMA#271542, IBA#138

  3. #3
    Mehrten
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    DeVern,

    The Wi-Fi version of the GS911 I own was connected via USB cable. I am aware that it will not connect via wi-fi to the older machines. Just would not connect consistently. Why??? Don't know.

    Our '02 KRS is a cruise control version. The cruise control cable is correctly connected with aprox. 1/4 in play. Cable routing is so direct there is no way there could be any crimping or cable binding.

    The main throttle cable is brand new, replaced after the second or third throttle body removal. The old throttle cable was not an issue really. Just though I should take the possibility of a bad cable out of the equation.

    The throttle closes with a nice solid sound upon release, and by visual assessment all bodies are closing as they should with the TVA removed.

    The increased idle has come on gradually over the last six months or so. She has been parked a lot over that time.

    Two other "modifications" to note. One, the left most throttle body spring has been disconnected. By disconnected I mean it is still in place but has been unhooked thus adding no tension to the cable. I did this to relieve the amount of pressure it takes to open the throttle and hold it open.

    This particular K12RS has a very tough to open throttle. I've owned two other K12RSs and their throttles were no way as tough as this one. I attribute it to the o ring friction between the bodies, though I really am not sure why.

    Second, I do not have the "push" throttle cable installed. That is the cruise control cable that has a cruise control cutout switch at the throttle bodies. Again this was done to alleviate the amount of force it took to open and hold open the throttle.

    When I bought the bike used in 2012 it had an idle problem. It was corrected and has remained corrected up until recently.

    Right now I have the TVA adjusted to 38 mm extended and not plugged in. The bike runs great and idles between 1,100 and 950 depending on how warm the engine is.

    Thanks for the comments and I hope the additional info will help steering me in the right direction.

  4. #4
    Registered User GTRider's Avatar
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    Deryle,

    It sounds then like you have bracketed this down to the TPS/TVA units. I mentioned the cable because I have had hidden internal breakage on a cable that still allowed the cable free movement in one direction but stopped short in the other. Unfortunately, those are spendy bits but at least they are still available. I wonder if the stiffness you are noting in the throttle, and possibly the throttle bodies, is leading to excessive wear on the TVA? And perhaps that unit was replaced as part of fixing the earlier idle issue?

    Good luck and do keep us updated,
    DeVern
    DGerber
    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
    BMWMOA#52184, AMA#271542, IBA#138

  5. #5
    Mehrten
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    DeVern,

    I have two throttle cables in the used/abused parts bin. One has a break/twist with a wire or two sticking out - garbage. The other lost the little ends off the throttle stay at the end of the throttle where it butts up against the throttle bodies. I have devised a repair and I'm keeping that cable for a spare.

    K1200RSs are known for tough throttles. Our '98 and '04 were both tiresome without using the cruise control. Rotti's pull is just a bit tougher, hence I uncoupled one of the springs. Changes the throttle pull quite a bit.

    A bit more info...

    We rescued Rotti from the local Honda dealer in Oct 2012. They took her in on trade with 62,303 miles on her. We are the sixth owner. We know the first through fourth owners, not the fifth. The forth and fifth owners abused the bike and did no maintenance or repair.

    I did a complete resto on her including the clutch o ring that had filled the bell housing with grunk. I dug grunk out with a putty knife and sprayed the housing with a high pressure hose pumping straight WD 40. Took two days to clean out the housing.

    The clutch was packed with grunk. I put it in a metal wash tub, doused it with brake cleaner and then burned it dry. Then I doused it with gasoline and burned it dry. Lastly I doused it with Acetone and burned it dry. It had plenty of meat left on it and has performed flawlessly these last 36,000 miles.

    After a valve adjustment the engine has run smoothly and pulls strong. A typical brick that should run for ever if properly maintained.

    I'm going to replace the TVA first. The GS911 has repeatedly stated it needs attention so it'll be first.

    Right now with the TVA manually set and not plugged in, the bike is ridable, though I would prefer the TVA be installed to compensate for cold starts, fan draw, ABS draw, etc.

    I appreciate your comments and thoughts.

  6. #6
    Registered User GTRider's Avatar
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    Deryle,

    Kudos on rescuing the bike from the unappreciating! Sounds like you’ve had quite a resto project on it and it has paid off in enjoyable riding.

    My ‘04GT has the normal hefty throttle pull, which is part of the reason i so appreciated the cruise control. Your experience tells me that next time I peel the tupperware to flush the brakes I should replace the throttle cable while I’m at it. That bike has 100k on it, 50k of that has been pulling a sidecar w/passenger and luggage, and it still runs a champ.

    Good luck and keep us updated!

    DeVern
    DGerber
    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
    BMWMOA#52184, AMA#271542, IBA#138

  7. #7
    Mehrten
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    A response to my request for help with comments:

    "Can the TVA mounting position be shifted? "

    No. You can't shift the TVA position without modifying the mount or the TVA itself. The TVA when fully extracted should be within a few thousands from the throttle arm. I don't have the exact number on hand though the dialog was "the thickness of a piece of paper" or so.
    The throttle arm adjusting screw is one of the painted screws "that should never be touched."

    "Give it another starting point? "

    No. See above.

    " If the starting point is shifted and the brain drives it to the high idle, then it looks like it might be the brain$$$$$$. The brain is driving the TVA to what the brain thinks is necessary for "proper engine operation" in "this condition.""

    Understood.

    "Or... What conditions drive the brain into a high idle mode? "

    There are several:
    Cold temperature; pull on battery/charging system as when fans come on or when ABS is activated; and/or sensing a low idle, below 1050 I believe, will trigger the TVA to extend thereby increasing rpms.

    " Did some sensor fail, and it has gone to a high idle to "compensate" or prevent it from stalling on a throttle chop or something. Does the
    GS-911 give some hints to what happens on various sensor failures?"

    There are several temp sensors. There's one on the water pump and one on the right side of the cylinder head. The sensor on the right side of the cylinder head is the Engine Temperature Sensor.
    There is also an ambient air temperature sensor in the intake manifold.
    The GS911 shows the engine temperature and the ambient temperature as reported by the bike. The ambient air temperature reported by the bike was +- a degree or two from the ambient air temp in my shop taken with an IR temp gauge.
    The water temperature shows on the dash. The GS911 I am using doesn't show water temp. I will check again to be sure on that.
    Each time I set the TPS and remounted the TVA the GS911 reported a problem with the TVA. I believe based on the length of the red line on the GS911 scale that the TVA was extending too far.
    Just to see what would happen, I pulled the TVA and using a 9 volt battery set the TVA to the fully extracted position. At the fully extracted position it does not touch the throttle arm.
    When left in the fully extracted position and remounted but not plugged in, the GS911 after a TPS setting reports all is well.
    I have speculated that the TVA may have "jumped a tooth" and is not setting correctly when told to retract. Or...the brain has an issue. That would be a bummer.

    "I would not think it is a ignition sensor. "

    The GS911 Hall check was green meaning all was right.

    "You have water temp covered. (I have not compared your resistance value to what is published out there.) Clutching at straws. I suspect there is an inlet air temp sensor. If so, is it good?"

    See above on ambient air temperature.
    The temperature figures I reported are from the GS911 taken from the Engine Temperature Sensor. The OHM readings were taken by disconnecting the Engine Temperature Sensor and using a multi meter set at 2k ohms.
    When the Engine Temperature Sensor hit aprox. 218 f the water temp gauge on the dash was at about 2/3s, where I'd expect the fans to come on.
    Per reading on the web, it's the Engine Temperature Sensor that turns the fans on/off.

    "Do you have an O2 sensor and a cat? If so, what does the O2 sensor output look like? The GS-11 will show that no? The O2 sensor could be "stable" looking for exact lambda. Or it could bounce rich and lean keeping the cat clean. (Cars do that.)"

    Yes and yes. Rotti has a stock exhaust with a catalytic converter and an O2 sensor.
    The GS911 O2 Sensor graph readings once warmed up were bouncing up and down as it searched for the best mixture. That is how it should be.

    "Are there any other sensors that feed into the brain that controls mixture? I can't think of any."

    "Shifting the TVA mounting point and seeing what happens might be the best indication that it is "something else" or the brain. "

    See above on shifting the TVA.

    One of the things I haven't done is unplug/plug in all the connections including the brain.
    The TPS gets 5 volts. That’s not a lot of volts to overcome a slightly corroded connection.
    I did test the voltage to the TPS per the TPS test procedures though I did not record the numbers, my bad.
    Next week I should have a used K1200RS Throttle Body Assembly complete with TVA and TPS that I ordered from Beemer Boneyard. The donor bike had a lot less miles than Rotti, a lot.
    The used TVA and TPS will give me another set of data points and will definitely keep me busy.

    Deryle & Wanda Mehrten
    Sierra Vista, AZ USA

  8. #8
    Registered User AntonLargiader's Avatar
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    Interesting problem! If you have another throttle bank on the way, I think the first step will be to compare the two and see why your old one is so stiff. That doesn't seem right, and the changes you've made are wildcards in the troubleshooting IMO.

    However, if the TVA is being told to raise the idle speed, then it seems that the ECU has its own reason for doing that. You have it disconnected now; if you plug it in I assume it will immediately extend a bit to raise the idle up to 1500? Seems you could compare that behavior to another K12 and see if it does the same thing and if it has the same effect. Easier said than done, I know. I do have a K12 at the shop that I may be able to observe.

    I went through the identical issue with an R12C, years ago, where the throttle opened pretty dramatically when the key was turned. I don't remember all of the details but it was a very underdocumented system on that bike, at least at the time.
    Anton Largiader 72724
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  9. #9
    Mehrten
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    Anton,

    Thanks for the comments.

    The used throttle body set should be here Friday. Oh boy!

    Most of my time the last couple of days has been on the TVA. Its easy to get to and "play" around with.

    It is receiving a signal from the ECU and will extend or retract.

    I cut out a piece of an old rubber inner tube and made a rubber "shim" to fit behind the TVA. Was it getting a signal to move so far or a signal to generate an specific RPM?

    With or without the additional 1.5 mm behind the TVA Rotti idled at the same 1,500 rpm. The TVA was extending farther out with the shim and retracting without the shim.

    When I set the TVA to fully extracted and not plugged in, the bike idles at 800~900 rpm as it should. Once the TVA is plugged in the idle goes to 1,500 or more.

    So it would appear the signal from the ECU is either flawed, or the ECU is getting a signal from possibly the TPS causing a flawed signal to go to the TVA.

    Getting to the TPS is a bit more difficult: pull the tank, the intake/air chamber, unhook the engine breather hose, remove the ground wire, drop the throttle cable.

    After an adjustment on the TPS its everything in reverse to see if there was any change. One iteration can take an hour or more depending on how much trouble the breather hose gives me.

    Yes, a disconnected spring may be part of the problem in that the force to close the throttle and push the throttle arm against the TVA's nose switch is reduced. I don't think so though, they close with a nice solid sound.

    A weak battery could be causing the rpms to rise to keep a higher charge??? Just to be sure when I get time I'll take the battery to my local shop and have them load test it. If it fails I'll get a fresh one.

    The other sensors - ambient temperature and engine temperature - from my testing seem to be working.

    It comes down to ECU or TPS...or if I'm lucky a loose or corroded wire connector(s).

    Again thanks for the comments.

  10. #10
    Registered User AntonLargiader's Avatar
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    I would see if moving the TPS did anything. It's the same TPS as the Oilheads use, so they are all over the place. I probably have a few. Could be that the engine thinks you are applying some throttle, or that it needs to apply throttle to get to the correct position.

    I have a K12RS coming in tomorrow for a clutch so I'll be able to have a good look at what it does.
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  11. #11
    3 Red Bricks
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    Deryle,

    Sure sounds like the brain thinks the engine is cold, but you said you checked the sensor.

    Is the temp sensor you tested the one that goes to the FI computer (motronic)? On early (K75 and K100) there were separate sensors for the gauge and for the fan. Not familiar with K12s.

    Are the numbers you got when testing the sensor the ones BMW specify?

    Are the pin connections to the motronic clean (especialy the ones from the temp. sensor)?




    Last edited by 98lee; 07-29-2021 at 10:12 PM.
    LONG MAY YOUR BRICK FLY!

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  12. #12
    Mehrten
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    Lee,

    Yes, it does seem that she goes into cold idle and never gets the signal that she's warmed up.

    The Engine Temperature Sensor is located on the side of the cylinder head and sends its signal to the ECU.

    The Water Temperature Sensor is on the water pump and only goes to the dash gauge.

    Here are the OHM readings I took at the Engine Temperature Sensor connector. The temperatures are what the GS911 was showing in Realtime Values.

    75 f = 1.000
    100 f = .900
    140 f = .590
    190 f = .256
    200 f = .200

    Truthfully I have not searched for what BMW says the readings should be. The readings "appear" correct. That old "assume" game.

    The fans come on at about 218 f.

    Haven't done an unplug/plug yet. I'm waiting for the used pieces to come in and see what the GS911 thinks of them.

    I'm planning on plugging the used Throttle Body set with the used TPS attached into Rotti, then go through the GS911 TPS setting procedure.

    The used set is supposed to be here this evening.

    I appreciate the help.

  13. #13
    Mehrten
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    No luck…

    Friday I dropped off Rotti’s battery at my local shop. It passed a load test but I still had them charge it overnight. Picked it up Saturday morning and it read 12.8 volts after setting on my bench for an hour or two.

    The K1200RS used Throttle Bodies with TVA and TPS attached came in Friday. It was exactly what was pictured on Beemer Boneyards web site. Good on them.

    Though they were pretty clean I did a wash with some Simple Green. All the painted screws were painted as they should be.

    It was a bit tight but I was able to connect the used TPS and the used TVA to Rotti while both were still mounted on the used Throttle Bodies. Then I hooked up the GS911 and did the TPS set routine. The TPS was set correctly.

    I then pulled my Throttle bodies, attached the used TPS and TVA, went through the GS911 TPS set routine and got the “TPS is set correctly” message. I did it several times actually and was able to get the set correctly message repeatedly.

    Then I pulled the battery, waited a day and did the throttle dance.

    No luck, Rotti still idles at 1,500 rpm. So it would seem it’s not the TVA or the TPS. It's worth noting that Rotti did seem to rev a bit "easier" with the used TPS and TVA installed and "set correctly."

    Time to look at the Engine Temperature Sensor again and/or start an unplug/plug routine. This will get me into the loom more than I have on any of the three K1200RSs we’ve owned.

    TIA...

  14. #14
    3 Red Bricks
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    Can you find the pins for the temp sensor on the plug that goes to the ECU and test the signal from the sensor through the harness? Maybe there is some signal discrepancy in the harness.



    LONG MAY YOUR BRICK FLY!

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    Lee Fulton Forum Moderator
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  15. #15
    Registered User AntonLargiader's Avatar
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    With a GS911 you should be able to read the realtime values from the ECU. Then you will know what it thinks is going on.
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