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1Back to top Go down    Injection gating device on Fri Apr 17, 2015 2:57 am

K75cster

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After being corrected in another post for thinking the fuel injection earth return wire was one of two used to sync the fuel injection to the spark coil operation I began to wonder why in this day and age we haven't created a device to gate the pulse for a sync as needed. With something like a logic gate to gate the two injectors that the coil was to fire on. It would require 4 injector connectors and four harness connectors the gating device and some brown wires with a colour to distinguish which is which. Surely it would be just plug and play? would have to better the mileage of our bikes just by halving the wasted injection squirt. I've been looking on google for such a device but cant find one, it seems reasonable to just find an electronic gate and adapt it, anyone see anything wrong with this idea?



Last edited by K75cster on Fri Apr 17, 2015 2:58 am; edited 1 time in total (Reason for editing : sorry cant spell)


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

2Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 3:53 am

charlie99

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you would need another crank angle sensor ...to identify which of the cylinders to fire at the right time... as our timing signal would work 180 cam degrees (360 crank degrees)  out of time without issue as it stands at the moment

the sequential injection firing is all about a newer ecu with some form of feedback to the system (ox sensor etc . and the additional crank sensor ) and a higher injector open time per pulse don't know how you would get this to happen with the underseat icu that the 8 valve versions have
 
what was going around about the same vintage was alternate firing of the injector banks  in the higher than low spec engines

if you were going there keith ...would pay to put plug top coils in as well ?

but this would all require an new icu ...akin to ben kinghams machine ...larry romstat and many others !!!

forgot to add ....a camshaft sensor would be another way to go along the path ?


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

3Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 4:25 am

K75cster

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I was just wondering why something hasn't been done already, without touching the brain and applying a logic gate device to the wiring loom at the injector site (down there at the fuel rail) just by adding in the device. I was thinking it would be a simple gate from an A terminal to a B terminal on the in side where the return wires would be changed to pair up on either terminal with the switch activated by each pulse. That should not effect the efu under the seat, and it would even give constant 12v through the entire system as if nothing had been added but with each current flow of the pulse it would change to the opposite terminal. I'd think it would be a sealed unit that would only require the crank be turned 180 if miss aligned?


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

4Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 4:47 am

charlie99

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not totally keith

the injection quantities are still going to be lean with the double pulse rather than the 4 pulse ....been there just lately ...and its amazing how little difference it is from rich to lean

could be done but is tricky to find a definitive "set afm to this reading at this revs " type solution  

keep in mind the squirt timing is quite extended ( ie slow turn on - off ) in comparison to electronic switching capacity ....they have programmed in the delay - advance in the injection timing to real time ignition firing which also works on electronic advance timings

having said that ....I think rick (or someone )  mentioned  a mod to the icu for a flip flop injection control ...my memory says on the german forums ?

there are certainly enough modern devices out now capable of doing the job in a minimum amount of space ...with upgraded working specifications


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

5Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 5:10 am

K75cster

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Yes Charlie, I expect if we searched enough for it we could find a device to allow each injector to fire independently of the system, but looking at the portal for the injectors it appears what I should be looking for is something to interrupt the green yellow wires and make them dance to my request's. Just have to find the right words to use on google and I might be able to cobble something together (just to satisfy myself) for testing. Cant use it myself as the k75 don't have 4 cylinders.


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

6Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 5:25 am

RicK G

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Do it the easy way  http://www.diyautotune.com/catalog/microsquirt-c-35.html?osCsid=8458fd523cc226b1d9a5c672b65b0329


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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
    

7Back to top Go down    Re: Injection gating device on Fri Apr 17, 2015 6:27 am

Holister

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From what I gather the combined injector pulse system used by the L-Jetronic is reasonably efficient and there's little to no fuel loss. It's maybe just not as responsive as a sequential injection system. Fuel is delivered to the back of each intake valve twice every 720°engine cycle. When the valve is closed the fuel is simply vapourised and is drawn in at the next valve openning (at cold startup this doesn't happen as it should so the L-Jet has to deliver more fuel to compensate).

The idea I get is that by using a combined injection time the CU has greater scope to make adjustments to the injection time and those adjustments are evened out over the whole engine cycle. I'm just guessing here but while that would minimally reduce responsivenes I think it would produce a more reliable engine and would also alleviate, as I think charlie mentioned, problems with injector open and shut lagg times.I think modern injectors operate much more efficiently.

The problem with a gating system that would operate independantly to the L-Jet is that the injection flow time is accumulative in that fuel is delivered over the whole 720°engine cycle. Gate that off electronically and sequentially to each injector and they would be only getting 25% of the required fuel because you'd be effectively shutting off 3 injectors at a time, whereas they would all be open. Otherwise you'd have to instruct the L-Jet to increase the injection time accordingly.

Also, while the HES generates 2 signals per 360°crank or 4 per 720°engine cycle (good for 4 cylinder sequential injection), the FICU divides and shapes those signals into just 2 triggering pulses per 720°engine cycle. I think you would have to replace the CU to achieve 4 cyl sequential injection.

I read somewhere last weekend that the Motronic is actually capable of 1+4 / 2+3 injection cycle but this wasn't utilised in the 16V K series. I'd say that BMW would've given that quite a bit of thought. Would be interesting to hear their reasoning behind that decision.



Last edited by Kaptain Holister on Fri Apr 17, 2015 8:27 am; edited 1 time in total (Reason for editing : typo)


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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
    

8Back to top Go down    Re: Injection gating device on Sat Apr 18, 2015 5:17 am

K75cster

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Rick Thanks I will be some time in that store looking at all the goodies, Taa

Kaptain, It sounds odd but I am thinking I can halve the injections as I'm not entirely sure the 3 after ignition are going to be kept atomised and ready for the induction stroke to ask them in. Maybe the last 2 squirts would be ok-ish but as the atomisation starts to clump you aren't looking at a clean burn. It seems that you are saying the mototronic system is a wasted squirt system such as I'm considering at the moment. Interesting. Will have to look at the 1100 site as I don't know squat about them. With the K100 I'm just suggesting the squirts at close to DBC aren't necessary. Mind you I don't know any better with regard to the fuel induction needs. Just putting it out there


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

9Back to top Go down    Re: Injection gating device on Sun Apr 19, 2015 3:59 am

Holister

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@K75cster wrote:Rick Thanks I will be some time in that store looking at all the goodies, Taa

Kaptain, It sounds odd but I am thinking I can halve the injections (the engine wouldn't run) as I'm not entirely sure the 3 after ignition are going to be kept atomised and ready for the induction stroke to ask them in. Maybe the last 2 squirts would be ok-ish but as the atomisation starts to clump you aren't looking at a clean burn (The injectors only squirt twice per engine cycle even tho there are 4 signals from the HES).
K100 fuel injection is accumulative over the 720°engine cycle, that is, fuel from both squirts is added together to give the required amount of fuel for that cylinder on that cycle. For fuel to burn it must first be vaporised and mixed with air. Atomisation simply aids the transition of liquid fuel to a vaporised state. Fuel is specifically delivered to the back of the intake valve which is the hottest part in the intake chamber where fuel injected before valve opening is kept vapourised due to the ambient temperatures until it is sucked into the cylinder. The only time fuel is lost in the way you describe is when the engine is cold and pre-delivered fuel is not vaporised completely (fuel can vaporise at low temps as well, just not as quickly). L-Jet compensates for this by increasing fuel injection time until the engine is warm enough to promote complete vaporisation. This is called 'cold start enrichment'.
The L-Jetronic system may not be ideal by today's standards, but it was considered to be fairly advanced back in the early 80s and was introduced by BMW in response to new government emissions regulations (this wouldn't be the case if ½ the fuel was being wasted). It certainly produced a cleaner burn and cleaner emissions than previous carburetion systems.

It seems that you are saying the mototronic system is a wasted squirt system such as I'm considering at the moment.
The motronic ECU is designed a little differently to the L-Jet. The Motronic incorporates the ICU as well and while it does apparently produced an injection pulse that is capable of synchronising with the HT ignition (1+4 fire together and 2+3 fire together), the injection pulses, to the best of my knowledge, are used in exactly the same way as the L-Jet, that is, all 4 injectors are opened and closed at the same time, twice per 720°engine cycle (2 crank revolutions).

Interesting. Will have to look at the 1100 site as I don't know squat about them. (The Motronic is used in the 4V K100) With the K100 I'm just suggesting the squirts at close to DBC aren't necessary (unless you could significantly and accurately increase fuel pressure or metered injection times, they are very necessary because each squirt is added together to give the calculated amount of fuel required for each cylinder to develop the power to meet throttle demand). Mind you I don't know any better with regard to the fuel induction needs. Just putting it out there
Hey Keith. A better path to go down would be what Rick suggested or even maybe investigate some of the fuel vaporisation technologies. I'm not saying that the L-Jetronic fuel system on a K100 is ideal, just that messing with the metered injection times will render the bike a non-starter.
Keep in mind that BMW build their bikes for reliability and longevity not race-track performance
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
    

10Back to top Go down    Re: Injection gating device on Sun Apr 19, 2015 11:48 pm

K75cster

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Yes difficult to say whether it would fail to start, but certain to put the willies up who ever tried it. I was thinking saving two squirts on each cycle would surely add up to an extra 4 or 5kpl over the whole tankful, but never mind its not something I'm in a position to fiddle with at present. Not whilst I cant find a switching device to put to an experiment.


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Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

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