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Moe Matrix

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Is there a way to disable the engine temp sensor, to prevent it from raising the idle, or is engine temp sensor required for startup?
Thanks.

    

Inge K.

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Moe Matrix wrote:Is there a way to disable the engine temp sensor,

Not a good idea....it's needed for calculating the air/fuel mix and determine when the fan is needed to run.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

mike d


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Sounds like you may have a fundamental problem if the idle is too high. After getting the bike up to temperature have you balanced the throttle bodies using the big brass screws?

Mike

    

BobT

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Why not set the idle to what you want when the engine is hot using the adjustment screw in the middle of the injector rail, where the cable attaches, and then use the cold start lever on the left bar when the engine is cold?
Would seem sense do adjust the idle the correct way instead of disconnecting things.

    

charlie99

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what idle speed when its warm ? is it too high at all, 
about 900 is pretty usual


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Moe Matrix

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everything on the engine is set up correctly, i just wondered why the bike idles at correct speed, then it gets warmer and rmps go higher, about 1100, then it goes back down to 975 after it gets real warm.  
i ride in the PNW, so the weather here changes every five minutes, and the slightest temp drop outside will make it run leaner, and higher.  it takes a long time for it to warm up in cold weather.  Just wondering why it must constantly change intake adjustment, and why bother putting brass screws to adjust intake when computer takes more than enough liberty to adjust things on its own...  I would rather it just stay at 975 idle at all times until i adjust the choke.  I have the brass screws down all the way, because there is no point in trying to adjust it at all since the computer does everything.  I just want it to do nothing until I want it to be done...
Thanks again.

    

Moe Matrix

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do I understand correctly, the engine temp sensor is what is responsible for leaning the intake.  the water temp sensor is to trigger the fan.  two different mechanisms?

    

Inge K.

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Moe Matrix wrote:I have the brass screws down all the way,

Could be the reason to your problem...the screws is to adjust the amount
of air to each cylinder at idle....and that each cylinder gets exactly the
same amount of air....basic setting is 1,5 turn from bottom.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

Inge K.

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Moe Matrix wrote:do I understand correctly, the engine temp sensor is what is responsible for leaning the intake.  the water temp sensor is to trigger the fan.  two different mechanisms?

Two different names on the same sensor.


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Inge K.
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BobT

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Sounds to me like you are meddling with things that you don't really understand.
If you have screwed the brass screws all the way in then why? Have you checked the inlet rubbers both above and below the injectors? Have you put a set of balance gauges onto the injectors as you are messing with brass screws?
Sorry to sound harsh, but you need to do things properly otherwise you might get erratic tickover speeds.

    

11Back to top Go down    engine temp sensor on Sun Apr 16, 2017 6:36 pm

Moe Matrix

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so the engine temp sensor is the same as the water temp sensor?
what about the air intake sensor?  one of them adjusts the idle and i really don't think it's necessary.  i would rather it did nothing.  if i want more air intake, then adjust the brass screws, but why adjust them if the computer is constantly messing with the intake levels???  that's why i have it bottomed out, because it's constantly adjusting them anyway, so whatever i adjust it to, 1.5 counter-clockwise, or whatever, it will still adjust it to the way the computer wants it, based on outside temp.  
as stated, after it warms up, the tach will rise from 975 to about 1200, then goes back down to 975.  I can hear when it starts to lean the mixture and rise the rmps.  I do not want that, and wonder if it is really necessary for the computer to constantly change intake settings, whether i have screwed with the brass or not.  
is there a way to get it to stay at 975 no matter what the outside temp is?  is there a way to disengage the air intake sensor to stop the computer from altering the mix every time the outside temps drop one degree?
I do no appreciate this particular function of the bike, or EFI, or whatever the problem is.  I do not want a computer to overthink what it's supposed to do.  I do not happen to believe this function of air intake sensor to raise/rix mixture is necessary at all, and i would like it disabled.  
that is all.

    

12Back to top Go down    air intake sensor on Sun Apr 16, 2017 6:42 pm

Moe Matrix

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someone here already stated they weren't sure why the EFI intake would begin its process of adjusting air intake mixture after it is already warmed up.  
why is it that the computer starts trying to adjust intake AFTER it's already warmed up?  where is this computer function when the engine is actually cold?  i just want it disengaged as it seems redundant and unnecessary, and not functioning when it should (cold).

    

BobT

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Are you altering the brass screws without having a set of vacuum gauges fitted?

    

Holister

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Moe Matrix wrote:so the engine temp sensor is the same as the water temp sensor?
The temperature sensor contains 2 thermistors which are both earthed thru the body of the sensor to the engine block. Of the two connections on the connector of the sensor, one goes to the temp control unit which controls the fan on or off. The other goes to the FICU (Fuel Injection Control Unit) which controls the mixture at start up when cold. About the only thing it will do is richen the mixture initially to get her started and then adjust the rich mix down to the point she's all warmed up. It will also signal the FICU in the event that the engine has over heated. The FICU responds by preventing the engine from restarting once the engine has stopped, untill it has cooled down to operating temps.
The sensor can be checked with a DMM to ensure the signal is within the specified operating range.


what about the air intake sensor?
The MAF flap only measures the volume of air passing thru the intake. The air intake temp sensor simply adjusts the signal from the MAF to the FICU so it can determine the 'mass' of air which is needed so as to mix the correct 'mass' of fuel.  This is because the volume of air changes greatly as nominal temps vary eg between a cold day of 10șc and a stinking hot day of 42șc

 one of them adjusts the idle and i really don't think it's necessary.
None of the temp sensors have anything to do with the idle. And the FICU does not 'lean' the fuel mix. About the only thing that will lean the mix is if you have an air leak or system parts have been changed with non-spec parts.

 i would rather it did nothing.  if i want more air intake, then adjust the brass screws, but why adjust them if the computer is constantly messing with the intake levels???  that's why i have it bottomed out, because it's constantly adjusting them anyway, so whatever i adjust it to, 1.5 counter-clockwise, or whatever, it will still adjust it to the way the computer wants it, based on outside temp.  
as stated, after it warms up, the tach will rise from 975 to about 1200, then goes back down to 975.  I can hear when it starts to lean the mixture and rise the rmps.  I do not want that, and wonder if it is really necessary for the computer to constantly change intake settings, whether i have screwed with the brass or not.  
is there a way to get it to stay at 975 no matter what the outside temp is?  is there a way to disengage the air intake sensor to stop the computer from altering the mix every time the outside temps drop one degree?
I do no appreciate this particular function of the bike, or EFI, or whatever the problem is.  I do not want a computer to overthink what it's supposed to do.  I do not happen to believe this function of air intake sensor to raise/rix mixture is necessary at all, and i would like it disabled.  
that is all.
I think you have made the assumption that BMW know sh!t about fuel induction. Many people have a problem understanding how fuel injection works especially on a K-Bike.
There is a trouble shooting page linked off the Portal tab. Have a read thru that and you probably have a better idea about how the 'system' works. The suggestions made above are good. Start by looking for air leaks such as injector kit (easy and cheap), Throttle Body (TB) rubbers (not so easy), crankcase breather (easy), engine cover seals and grommets (easy). These are all rubber parts.
Another issue I found is that the throttle cable may not be properly adjusted either at the handle bars or down on the TBs.
After all this, the BBSs (Big Brass Screws) can be adjusted with a vacuum gauge.

EDIT: I just had a read of your post #6.
....the weather here changes every five minutes, and the slightest temp drop outside will make it run leaner, and higher.  it takes a long time for it to warm up in cold weather.
Could be your MAF is Kaput and its sending a varied signal to the FICU. Maybe the temp sensor in the MAF is dud.
If it takes a long time to warm up in cold weather, it's very possible your thermostat is not working ie; stuck open or has been previously removed by a PO.

PS I think Kafflut had a problem similar to this which I think he solve after many months. Search is on the Portal tab.


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1988 K100RT     VIN No.  0094680
1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
     Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

15Back to top Go down    engine temp sensor on Mon Apr 17, 2017 9:58 am

Moe Matrix

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Thank you Holister for enlightening me on bmw efi.

    

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