Ulysses engine temp sensor

Discussion in 'Land of the Rising Sun: ADV Bikes from Japan' started by gdsob, Aug 17, 2013.

  1. gdsob

    gdsob Adventurer

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    I am troubleshooting an engine miss and bought a new engine temperature sensore from ASB. Problem is, i can't find the damn thing and I don't have a service manual. Can someone post a picture or tell me where it is?
    #1
  2. Hughlysses

    Hughlysses Long timer

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    The engine temp sensor is on the rear cylinder head, adjacent to the spark plug IIRC. You'll have to remove the outer and inner airboxes, and the airbox base plate to see it and/or remove it.

    There's also an intake air temperature sensor that sticks up out of the airbox baseplate.
    #2
  3. gdsob

    gdsob Adventurer

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    OK thanks. I am not seeing anything near the rear spark plug. I just changd the plugs and O2 sensor, so all the covers are off, but this has me stymied.

    It's really cramped in there, talk about 10 lbs. of poo in a 5 lb box...
    #3
  4. TeepS

    TeepS Full Circle Rider

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    The manual says to rotate the right side engine tie bar to access the sensor.
    You will need a slotted 1/2 inch deep socket to get it out too.
    Make sure to clean all the debris out of the area before installing the new sensor.
    The book says torque to 120~168 in/lbs (I would do 10ft/lbs.)

    NOTE:
    Do not operate the starter motor with the ground strap loose; bad things will happen.
    #4
  5. Hughlysses

    Hughlysses Long timer

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    I dug my manual out. I was wrong about placement; looks like it's closer to the center of the rear head.

    [​IMG]

    I'll also post a pic of the entire page from the manual in case there's anything else helpful- stand by.
    #5
  6. Hughlysses

    Hughlysses Long timer

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    Here's the complete page from the shop manual:

    [​IMG]
    #6
  7. vtwin

    vtwin Air cooled runnin' mon

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    [​IMG]

    It's pretty deep in there, the black wire off the center of the head.
    #7
  8. gdsob

    gdsob Adventurer

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    That would be infinitly easier to get to without the frame and other wires and hoses in the way. Thanks for the help guys.

    I ended up slotting a socket with agrinder and needed a wobble extension to access the sensor. Just came back for about an hour ride and still have the same problem with it cutting out and going to skip spark.

    I've done the following:

    New plugs
    o2 sensor
    Temp sensor
    Swap ecm's - stock and EBR race. I even cracked one open to check the solder joints and relocated from stock location.

    Got 77 miles from last tank of gas. Dealing with this for the last month or so and
    Amgetting pretty frustrated that i haven't fixed yet.
    #8
  9. Hughlysses

    Hughlysses Long timer

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    I'm sure that is immensely frustrating. Have you posted up in the Big, Bad & Dirty forum at Badweb? Somebody there may be able to help:

    http://www.badweatherbikers.com/buell/messages/142838/142838.html?1376867796
    #9
  10. gdsob

    gdsob Adventurer

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    Yeah, been scouring BadWeb and some really good info there. Figured out how to read the codes and only had the engine temp sensor code, so i am lost at this point.
    #10
  11. Hughlysses

    Hughlysses Long timer

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    Glad you found us. I'm pretty sure I've read of bad/intermittent grounds which could be a caused by a broken wire in the harness or a poor connection to the frame causing this problem.

    It's a good idea to re-do the ground connections anyway (there was a factory service bulletin about this). Find the ground attachment points in the sub-frame (I think there are a couple) and remove the bolts from them. Wire-brush the bolt threads clean. Take a flat file and file the paint off the bosses on the frame. Re-install the bolts using "star" type lock washers and no thread locking compound. The star will "bite" into the bolt head and terminal lug and ensure a good connection. Sometimes this will cure weird electrical problems like this.
    #11
  12. Mr. Canoehead

    Mr. Canoehead Taste Gunnels!

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    The manual shown is pretty good at explaining how the sensor works. It says that a low resistance indicates high temp. You have eliminated the sensor itself as part of the problem, so the next step would be to troubleshoot the wiring. I don't think that you have a bad ground, because that would cause a high resistance (ie Low temp). I think it is more likely that you have a short to ground (ie Low resistance, High Temp) upstream of the sensor. If you use something like ECM Spy, what does it show the engine temp as?

    I would try putting a 1k ohm resistor between the ECU out for the temp sensor and ground (disconnect the sensor first). It would see that as normal operating temp (150c) and should not skip fire (at least if it is doing it because of the temp sensor). If it still does it, then you could eliminate the temp sensor as the cause of the problem.

    Does it skip fire all time? Are you sure that it is not just a bad coil? Is the plug actually firing?

    I'm not a Buell expert but these problems can be a bear to track down and you want to approach the problem systematically.
    #12
  13. Mnrider2

    Mnrider2 Been here awhile

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    A good way to check for coil or plug wire issues is to remove the left side scoop,get the engine hot and spray the plug wires and coil with soapy water.
    #13
  14. Sharkguy

    Sharkguy chain lube applier

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    If I remember correctly there is a member over on Badweb that cured his skip spark problem by manually wiring the fan to a switch on the bars. Supposedly the thinking is that the fan is powered through the ecm and the draw is too much for the ecm to handle on some bikes. Wiring it to the bars on a switch and bypassing the ecm takes a big electricial draw off of the ecm. I'm sure others can explain it better, but it can be found over at badweb.
    #14
  15. Mr. Canoehead

    Mr. Canoehead Taste Gunnels!

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    You could do the same with a relay, if there isn't one already (that would be surprising).

    Send from my Droid using Tapatalk
    #15
  16. Hughlysses

    Hughlysses Long timer

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    The electrical system has a relay for the fan; the problem is apparently with the wiring harness or the internal circuitry of the ECM on the particular Uly that's being referrenced. The owner tried everything he could to eliminate the problem until in desparation, he wired a manual switch in to the relay that controls the fan. This switch grounds the wire from the relay that normally goes through the ECM. Apparently what was happening was that the small current required to close the relay for the fan was sufficient to cause "wonkiness" with the ECM. It's definitely a work-around fix, but it was simple and has proved relaible.

    I still think it's worthwhile to verify that the grounds in the tail section are good. If the ECM isn't grounded properly, it can cause really odd issues like this. Mr. Canoehead- your description of the operation of the sensor is obviously correct, however I think that a problem with the ECM grounding can result in it mis-reading the signal from the sensor. Excessive resistance in the ECM ground may mimic low resistance in the sensor.

    If the bike is actually going into skip spark, it should display a check engine light (flashing IIRC) while it's happening.
    #16
  17. Mr. Canoehead

    Mr. Canoehead Taste Gunnels!

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    Good point. I hadn't thought about ECU grounding affecting resistance measurement. However, that would cause all your sensors to read incorrectly (which may be the case here).

    If the microamps required to operate the fan relay is too much for the ECM, the ECM is definitely on its way out. Or maybe the relay was bad in that case, causing it to draw too much current from the trigger circuit? I'm guessing in that example, the bike went crazy whenever the fan started up?

    We haven't heard back from the OP but I would like to know why he thinks it is skip fire and not just a simple misfiring cylinder.

    I still think that using an ECM reader to look at the live data would be the next step in the troubleshooting process. Blindly throwing parts at the problem is expensive.

    Slightly off topic, I read an article a while ago about how BMW won't pay the car dealerships for replacing parts without justification just to prevent parts swapping as a diagnostic process.
    #17
  18. gdsob

    gdsob Adventurer

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    Guess it would help for me to subscribe to this thread..:huh

    I don't know if it really is skip spark, but it cuts out noticably after a while. The engine light sometimes comes on briefly then goes out.

    I am going to borrow a Fluke meter from work and check the resistance of the sensors, then re-do the grounds as suggested. It does act like it could still be a temp sensor issue, but I'm just guessing at this point.
    #18
  19. red450

    red450 WEE-A-BOO

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    Does the engine actually stop running or does it just stumble?

    My 06 had a lot of running issues, stalling, stumbling, surging and poor fuel economy. Turned out to be a bad TPS. Do you have ECMSpy and a cable?
    #19
  20. Hughlysses

    Hughlysses Long timer

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    If it actually goes into the protective skip spark mode, the engine light will start to flash. From the owner's manual:

    "If a fuel-injected engine exceeds normal operating temperature, the engine will operate in a "skip spark" mode until the temperature is back in the normal operating range. Reduced power will be experienced until operating temperature returns to the normal range. The check engine lamp will blink warning the rider of this condition. The check engine lamp will only blink as long as the operating temperature remains above normal. If the check engine lamp blinks excessively or potential overheating is not suspected, see a Buell dealer. "
    #20