BMW K bikes (Bricks)

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1Back to top Go down    LE-Jetronic on Mon Jun 27, 2016 11:36 am

yetti.86

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Hi.
Does anyone know any details about K100 LE Jet unit? Oscilloscope waveforms measured on running engine, schematic, pictures of disassembled unit?

Thanks.

    

2Back to top Go down    Re: LE-Jetronic on Mon Jun 27, 2016 7:04 pm

Holister

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There's info floating around. You just need to search for it. The Jetronic is a very reliable unit and rarely needs attention. About the only thing that can go wrong with it is the plug can work loose if it's not secured properly or the pins can get a little corroded which interfers with signals from sensors.

Have a read thru the 'Troubleshooting' page (link is on the portal tab). You'll find info on the FICU (jetronic) there relating to input sensors and how to test at the input plug.

PM Crazyfrog for the password to the member's download section. You might find something there.

Do a 'forum search'. The search box is on the portal page. That will give you threads and posts relating to the Jetronic.

The unit is easy to open up if you need to get to the circuit board and some members here are familiar with the electronics.

If there's something specific you want to know about the FICU, you're better to post a more specific question. Cheers


__________________________________________________
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
    

3Back to top Go down    Re: LE-Jetronic on Mon Jun 27, 2016 7:15 pm

yetti.86

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Hi. Thank you very much for the reply. Smile
I'm also very familiar with electronic, thats why I dared to ask about details like waveforms or schematic. My unit and related sensors are working properly. I need no troubleshooting, just thinking about various mods.

Yes, I've specific questions Smile
Does anyone have schematic of Bosch Jetronic 280 000 313?

    

4Back to top Go down    Re: LE-Jetronic on Mon Jun 27, 2016 9:05 pm

RicK G

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Hope this helps


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

5Back to top Go down    Re: LE-Jetronic on Tue Jun 28, 2016 4:16 am

yetti.86

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Hi.
To be honest, I found this picture a month ago and it launched my curiosity about LE-Jet.

For example what is purpose of the input 23, which is not documented in any K100 troubleshooting guide and as far as I remember there is no 23. pin used in the K100 harness.
Then I noticed, that part number of the unit on that pic. is a bit different then part number of LE-Jet in our bikes. It is of from some BMW car.
http://www.unofficialbmw.com/all/motronic/all_motronic_part_numbers.html

Basically, LE-Jet is ""only"" generator of PWM, whose duty cycle directly depends on the voltage which is produced in MAF's voltage divider and so...Am I correct?

But I belive (and now my hypotesis starts Surprised)), that if Bosch manufactured L/LE-jets for various vehicles, that the core of those units was the same.
I would believe that these units differs by e.g. values of R, C elements which are responsible of PWM creation (to produce engine specific characteristics)

And that is why I've asked for any details about LE-Jet. Of course, I can open and trace my own unit, but prior that I've tried if some one else, did it before Smile.

    

6Back to top Go down    Re: LE-Jetronic on Tue Jun 28, 2016 6:20 am

kennybob

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i've swapped 4-cylinder car motronic units to run other cars (bmw,porsche, volvo, saab) and also to run a motronic k bike. All the internal circuits were the same, the difference was in the eprom that contained the timing and fuel curves.

i'm tracing an L-jetronic board for a 3-cylinder right now--it too has additional circuits that are not wired on the bike's connector. My guess is that it is for diagnostic and serial port communications used during testing and checkout of the control units

    

7Back to top Go down    Re: LE-Jetronic on Tue Jun 28, 2016 9:27 am

RicK G

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That diagram came from a LE-Jet book that I found on the net quite a few years ago and was the only info I have found. Bosch treat the whole lot as a state secret even though they will never make any money from it again. Maybe they can be convinced to release the info we want in the interests of the classic bike owners.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

8Back to top Go down    Re: LE-Jetronic on Tue Jun 28, 2016 10:25 am

yetti.86

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I think not only motorcycle owners. LE-Jets were used especially in the cars.
I must to disassemble my unit. Surprised). I'm really curious. Unfortunately I'll see my old girl up to a month.

The circuit posted by Rick is nice and despite the lack of information about ICs like BB 0124 or BB 0126 it seems that is in the accordance with the principle of operation described in the Bosch official brochure about L-Jet.

E.g. here. pdf page 20-21
http://www.cardiagnostics.be/-now/Educational_sites_bestanden/BOSCH%20L-Jetronic%20Injection%20Manual.pdf

It seems to me, that IC labeled BS30 is the part of "multiplier stage". I'd be very happy, if there is an extra unused input to the multiplier stage.
I'd like to play a bit with the mixture, but I don't want to rebuild my K to microsquirt or motronic. I'd like to keep the original harness, original LE-Jet unit.

My idea is to have an extra MCU beside the original LE-Jet which would be able to slightly modify the mixture depending on whatever. To improve mpg, reduce vibs, ...,. But the core functionality would be provided by the original unit, so that you could anytime throw the supplementary circuit away.

    

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