91 k100 16V water temperature sensor temperature/ohms measurements

[TommyT]

I am trying to test the water temperature sensor in 1991 K100 16V. I remove the sensor and have measured various resistance values at various temperature. I have tried searching here for the values that I should be getting and I found this https://www.motobrick.com/index.php/topic,327.msg506.html#msg506 but the values posted do not seem match some values from a screen shot someone posted  to FB recently.
the values at the MB post:
14 F - 9.6K
32 F - 6.4K
50F - 4.3K
68F - 3.0K
86F - 2.1K
104F- 1.5K
122F- 1.0K
140F- .79K

I am getting the following values (my sensor is part #0280130055):
68f(20c) 2.57k
100f(40c) 1.43k
140f(60c) .685k
176f(80c) .400k
210f(99c) .210k

I am not sure that the sensor is bad from what I am reading. Should I replace it? For the amount of work to get at it (remove radiator) and that the sensor is about $25 I am tempted to just install a new one. I am testing this because on the 2 test rides I could take on the bike after getting it to run before it got too cold to ride here, it start and run great until about 20 minutes later and  then it would start to blog down when accelerating.

Edit:
I found the values listed in the screen shot at https://forums.bmwmoa.org/showthread.php?93214-Testing-K75-K100-temperature-sensor

Would the values for the Jetronic bike's sensors be the same as the 16V Motronic ones???

[The Mighty Gryphon]

I don't know all the different values, but the critical ones are at room temperature(60-80F) and at operating temperature(~190-200F).

The resistance at room temperature is 2500 ohms(2.5K).  If it's colder than that, expect a higher reading, maybe 3000-3900 ohms if it's freezing.

At operating temperature it should be around 250 ohms(0.25K).

If you are close to those readings you are probably okay. Cheap meters are notoriously inaccurate at lower resistance readings.   Just make sure to clean all the connections including where the sensor is screwed into the engine.

[volador]

Temp Sensor negative temperature coefficient Steinhart–Hart equation R= Rt*exp(A1+B1/T+C1/T2+D1/T3), where exp is the inverse of ln the natural log

rbm's graph https://drive.google.com/file/d/1cjXhg42x3anfz4vga4-XegjMGZVhHiXG/view

[volador]

You can just use a test light and count the pulses or temp light in the cluster
Motronic Fault Codes ~ author frank warner in .PDF

OR on interwebs
http://web.archive.org/web/20080405214941/www.geocities.com/fwarner_au/mc_things/K_fuel_injection.html

http://www.k11og.org/forum/viewtopic.php?t=2110

[TommyT]

Temp Sensor negative temperature coefficient Steinhart–Hart equation R= Rt*exp(A1+B1/T+C1/T2+D1/T3), where exp is the inverse of ln the natural log

rbm's graph https://drive.google.com/file/d/1cjXhg42x3anfz4vga4-XegjMGZVhHiXG/view

I don't understand, is this saying all temp sensors have the same temp/ohms measurements or is this chart  the one for the 91 K100 16V?

[TommyT]

You can just use a test light and count the pulses or temp light in the cluster
Motronic Fault Codes ~ author frank warner in .PDF

OR on interwebs
http://web.archive.org/web/20080405214941/www.geocities.com/fwarner_au/mc_things/K_fuel_injection.html

http://www.k11og.org/forum/viewtopic.php?t=2110

The "K_fuel_injection" link matches the screen shot I posted. I misread the image, the values I copied were for the air temp sensor.

[volador]

Motronic Fault Code 1223 Engine Temperature Sensor for M2.1 & M2.2

K models to 1993- VOM resistance Pin 21 of Motronic MCU plug to Pin 32  ≅ 2.5KΩ @ 20°C

K models from 1994 & R1100 Pin 7 to Pin 14

All K-temp sensors follow the same curve +/- 15% Ω

[TommyT]

Thanks all for the info. I went ahead and installed a new water sensor since I had the radiator out (a bit of a PITA) which only then you can access the sensor, and it was only around $25. I did test the new one before I installed it and the values for it were close to the one I had. Once we get some warmer temperatures and ice free roads (April??) I will see how it runs and check for Motronic codes. Plus now I got the temperature gauge working, the black wire from the other sensor was broken under the gas tank, I can see the temperature as I ride it.

[volador]

http://www.motobrick.com/index.php/topic,10402.msg97990.html#msg97990

2 pages in Luigi cleaned ignition switch and all was well then TBsync & CO Pot adjust

[TommyT]

http://www.motobrick.com/index.php/topic,10402.msg97990.html#msg97990

2 pages in Luigi cleaned ignition switch and all was well then TBsync & CO2 Pot adjust

Thanks, from what I read he had problems starting his bike and keeping it running. This bike starts everytime I have tried it in the garage, and on the couple rides i could do it runs strong until 20 or so minutes and then slowly degrades, but does not stop running. If I can get a break with the weather I will try a ride to see if the sensor was off enought to cause the Motronic to think the engine is still cold.

[volador]

http://www.motobrick.com/index.php/topic,2561.0.html

Your first screen shot gives procedure to obtain Motronic fault code if one exists. Do not disconnect the battery nor the connector to the Motronic Control Unit before accessing the fault code. Disconnecting the battery or the MCU will erase the code. Erase fault memory: pull fuse 5 for some seconds.

http://web.archive.org/web/20080405214941/www.geocities.com/fwarner_au/mc_things/K_fuel_injection.html

[Laitch]

This bike starts everytime I have tried it in the garage, and on the couple rides i could do it runs strong until 20 or so minutes and then slowly degrades, but does not stop running.

I read over your posts about this moto but didn't read that you refreshed the fuel hoses in the tank, the vacuum hose, or the fuel filter. What's the status of those items? Collapsing or restricted hoses and a partially clogged filter could contribute to these symptoms.

[The Mighty Gryphon]

Thanks, from what I read he had problems starting his bike and keeping it running. This bike starts everytime I have tried it in the garage, and on the couple rides i could do it runs strong until 20 or so minutes and then slowly degrades, but does not stop running. If I can get a break with the weather I will try a ride to see if the sensor was off enought to cause the Motronic to think the engine is still cold.

I haven't seen what you are experiencing, but that sounds like a classic case of dying Hall Effect Sensors.  When they get hot they stop working, then when they cool off, they start to work again.  Usually, they kill the engine, but in your case they may be just starting to fail and not giving a good consistant signal.

Question: If you let the bike cool for a half hour or so, does it run properly again?

[volador]

The Motronic System has the capability of monitoring its operation. When a malfunction occurs, the Motronic Control Unit (MCU) detects it and stores the information about the malfunction in a portion of the control unit known as the fault memory. The information in the fault memory is in the form of a numeric code. These codes correspond to an actual circuit or component that is found to be defective on the system.

If a fault is detected, the MCU will provide a substitute value for the faulted signal. This allows the rider to continue riding the motorcycle, even with a fault in the system, to obtain service.

The only input signal the MCU does not provide a substitute value for is the engine speed and reference signals produced by the hall sensor. The MCU will set a fault code but can not function without this signal

Two Motronic Systems are used: M2.1 with CO potentiometer (without catalytic converter) and M2.2 with O2 sensor (with catalytic convertor). The fault codes other than the CO potentiometer (M2.1) and O2 sensor (M2.2) codes are the same.

The Motronic System relies on signals from the idle CO potentiometer and the throttle position potentiometer for correct mixture throughout the RPM range.
Service Bulletin  Fuel Supply & Adjustments  September 1991   13 023 91 (2475)

http://www.k11og.org/forum/viewtopic.php?t=2110&start=0&postdays=0&postorder=asc&highlight=

http://www.largiader.com/articles/motronic.html

[TommyT]

http://www.motobrick.com/index.php/topic,2561.0.html

Your first screen shot gives procedure to obtain Motronic fault code if one exists. Do not disconnect the battery nor the connector to the Motronic Control Unit before accessing the fault code. Disconnecting the battery or the MCU will erase the code.

http://web.archive.org/web/20080405214941/www.geocities.com/fwarner_au/mc_things/K_fuel_injection.html

I will try this later today or early tomorrow and post the code if I get one.

Thanks

[TommyT]

I read over your posts about this moto but didn't read that you refreshed the fuel hoses in the tank, the vacuum hose, or the fuel filter. What's the status of those items? Collapsing or restricted hoses and a partially clogged filter could contribute to these symptoms.

I cleaned the tank and replaced the fuel pump (clone) and gas filter and the lines in the tank. The vacuum hose looked good but I will look closer at it again soon. I did test the pump pressure, it was 35 psi at the fuel injector rail. Again if I can get it out to test ride it and it starts to blog down I will try opening the gas "cap" to see if a tank vacuum occurred and if starting right up again if the "blogging" reoccurs or if it will run well again for xx minutes and then starts again to blog down (maybe the pump is not keeping up with the demand).

[TommyT]

http://www.motobrick.com/index.php/topic,2561.0.html

Your first screen shot gives procedure to obtain Motronic fault code if one exists. Do not disconnect the battery nor the connector to the Motronic Control Unit before accessing the fault code. Disconnecting the battery or the MCU will erase the code. Erase fault memory: pull fuse 5 for some seconds.

http://web.archive.org/web/20080405214941/www.geocities.com/fwarner_au/mc_things/K_fuel_injection.html

I tried this test, I only get a "3333" code, the fan test. I though maybe I grounded the pin too long but I tried the test 4 or more times and I only get the fan test and no "4444" code (??). I had run the engine for twenty minutes in the garage for 15 minutes or until the fan came on a few days ago. If a code was going to show up it would have happen then.

[Laitch]

. . . if starting right up again if the "blogging" reoccurs or . . .

Blogging only occurs when you're writing an Internet diary. :-)

Don't ignore TMG's suggestion concerning Hall sensor malfunction.

[TommyT]

Blogging only occurs when you're writing an Internet diary. :-)

Don't ignore TMG's suggestion concerning Hall sensor malfunction.

Blogging, yes that's what I seem to be doing here, ha. Now the bike is bogging down, not blogging or that least not while I am watching.

I will try to check the Hall sensor, looks like it might be 50 here on Monday. If the ice on my long driveway  can melt I will try a test ride. I guess I could use my heat gun to blow on the Halls sensor cover while it runs in the garage.

[alabrew]

Big Red's failed on a purdy hot 95 degree day. I babied it 20 miles home with a stop or two when it died. I could hear that only one side was working and the pump was pulsing, did better if the rpm's were up over 4,000. Took the one off the RS to test, it solved it, so the RS gotta a new one from EME.

[TommyT]

An update. Finally the ice melted on the driveway and I got the bike out for a run. I let it warm up for awhile before heading out. I did not have the bogging down problems. Yeah.

[The Mighty Gryphon]

Hall effect sensors.  Too cold for them to get hot enough to be whack.

He'll be back.

[TommyT]

An update: Well it was not the temp sensor or the Halls sensor. Short story, crap in the the gas tank was getting sucked up into the fine mesh non OEM fuel pump screen and clogging up it up enough to reduce gas flow.

Long story, I did finally with warmer weather get the bike out for a longer ride.  At about 15 miles the bike would blog down off and on until I would turn the bike off for a while.  The bike is a 91 K100 RS which I bought last fall. It had sat for close to 10 years. The gas tank was full of crap which I though I had cleaned out completely. After a fair amount of work and a new ebay fuel pump I got the bike running over the winter. After the recent rides where the problem reoccurred, I decided to check out the fuel pump and I found that the fine mesh screen that came with the pump (it only lets gas into the pump from the bottom and not the sides also like the BMW screen) was dark and had "stuff" on it that I could wipe off with my finger. I looked into the tank and where the pump goes in the bottom of the tank was some dark sediment in the crease. I cleaned the screen and sucked out the sediment. After two 50 mile hard rides in 60 degree weather there been no more problems. Yeah!

[volador]

An update: Well it was not the temp sensor or the Halls sensor. Short story, crap in the the gas tank was getting sucked up into the fine mesh non OEM fuel pump screen and clogging up it up enough to reduce gas flow... Yeah!

You forget the vinegar the first time?

Thanks for the update. Stay safe

[TommyT]

You forget the vinegar the first time?

Thanks for the update. Stay safe

Nope used a couple of gallons and then flushed it. But I must have left some crud in the tank that worked it's way to the pump area. My bad.

You stay safe too! Hopefully the peak is starting soon in the city. When things get better come up for a ride in the Catskill with me.