So this has been brought forward from TWB pride and Joy thread as it became technical discussion on LE Jetronic and pretty much started my investigations with this comment.

Themason wrote:There is nothing to be gained from a Megasquirt injection system except the opportunity to get it very wrong. Whether or not you chose to go with Megasquirt or learn the black arts behind Bosch L-Jetronic, you will still have to learn the basics of fuel injection and the details of a particular system. Take it from me, L-Jet has no real shortcomings and is easily tunable with hand tools, once you understand what you are doing inside that black plastic cover over the potentiometer (and learn how to pry it off gently without damaging it).

There are automotive websites that explain what goes on inside an air flow meter and how to modify them. A one click reduction in spring pre-load on the vane changes throttle response a lot. Two clicks on some bikes is too much. You will have to learn how to adjust the potentiometer in suit with adjustments to spring pre-load on the vane. In reality it is easier than trying to suss out an AFR table on something like a Megasquirt. L-Jet gives you a dead flat AFR across the rev range if you keep the TPS installed. If you have spent any time dyno tuning an Alfa-N system you know this is not so easy to achieve on other systems.

L-Jet and the stock injectors can deliver more fuel than the engine can use, so don't fool yourself into thinking you can get more power out of some other form of fuel injection.

Which made me do 8 hours of research so far (s loads more to come ) but after my initial look this was my opinion so far

So I have started my research on both the LE injection (E is for open loop non lambda sensor type, that is non oxygen sensor with close loop response type). Initial thoughts as follows

LE injection system is an antiquated (but lovely guys I like these old girls remember) way to run a fuel injection system that relies on operating with a predetermined (open loop) fuel map instead of closed loop feedback controlled fuel injection that varies the fuel injector output according to real time data, whilst the closed loop system is useful for fuel emissions( dont really care) it is also advantages for fuel injection efficiency.
The FI(fuel injection) module in our girls isn't even microprocessor controlled, purely a analog (hardware solution) you purely follow the rpm signal through whilst it is divided down and condition (mainly by the rpm & afm signals) but post conditioned via capacitive & resistive slew rates fed via temp sensor et, then fed into a logic gate to clean up the signal and out to the injectors.
You can modify the afm preload and it is true that this will adjust (enrich) the outcome for performance at the exspense of fuel efficiency and emmisions but you can't measure real time and adjust accordingly through the rev range. Resistor changes can be made to the rpm rev limit (alot on this in forums alfas, volvo etc) and other points that will change max dwell etc and these can be changed and tested as at the end of the day you are just following a waveform with the scope to the injectors. Funny really you can think of the resistor changes as constant parameters in software for a micro controller, variable only at the design( variants for different car types) and manufacturing stage and burnt into OTP (one time programable) micro controllers.
However we all know how much difference a performance chip upgrade to a modern car can improve its power(it's just remapped).
What about tunning for a different exhaust system or modification like K1100 TB's etc or even better?.
The equation for lambda 14.7:1 is for max emmisions efficienty not power therefore a narrow band oxygen sensor is no good and a wide band sensor will be purchased so I can check O2 levels at different AFR's
So the go is a mega squirt 3 with the expander card for sequential injection with the version three main board, this will give me bluetooth to my galaxy note for tuning realtime on the road all up around $600 for the kit form (with $200 O2 sensor included)
The original ignition module will be used for logic level ignition sequencer driven from the megasquirt.
Not bad value when they offer the MS3 premade in a IP69 rated case (dont care for me) for around $1200 without the lambda sensor
Wow it is facinating reading about fuel injection systems
Halo

The nice thing that I have seen with L-Jet is that if you get idle CO at 2% the AFR will be very close to ideal for best power and the AFR will be dead flat across the rpm range. The hard part, and it's not really that hard, is getting the idle mixture set properly.

Yes, loosening the tension on the vane spring allows more overswing when the throttle is opened (which is where you get the improved throttle response), and it will be open more at any given throttle setting. This is why you also have to know how to reset the potentiometer.

The analog nature of L-Jet gives it a very nice feel, more like a good CV carb with none of that gritty throttle response too many Alpha-N systems, especially early 16 valve Motronic bikes, have.

Btw, my smog legal 2007 Street Rod with it's more modern digital engine management that reads throttle position, crank position and speed, intake vacuum, ion gap at the spark plug (GM ion-gap technology), intake air and coolant temps at best delivers mileages in the high 30's exercising all of my adult restraint, and a high speed hoon out here in the desert proptly drops the mileage down into the mid to high 20's. The AFR on the dyno is right at 14.0 : 1 except at WOT. My fiancee's Toyota Avalon gets better mileage than this! L-Jet won't allow the tight engine control necessary to pass current emissions standards, but that is really it's only fault. For real world riding, it is just fine.

I am glad that you two understand each other and speak the same language.

I have to go to bed after that.....my head hurts

Ain't you in bed yet.....

Inge K. wrote:Ain't you in bed yet.....

Have to wait for the wife to get to sleep

No no no....just admit it, it was the frightening picture.....
you went offline shortly after the angry mom showed up.

So Themason I have pulled the AFM out and adjusted two clicks counter clockwise and wow what a subtle difference idle went up from 1000 to 1300 rmp (will adjust down) has that slightly rich smell at the exhaust at idle. My favorite take off is 6 thousand and dump the clutch in first BUT normally I still have to feather it at the end of the first gear clutch dump as it gets bogged down but now IT JUST HOLDS the clutch dump. Foe the first time ever the front wheel lifted off the ground during a normal lean forward takeoff !!!!!!(only 50mm though).
So got to say great success with the very simple mod.
No re calibration Themason on the pot as not only does it has a more under damped throttle response (revs quicker with giving throttle response) I have modified the Lambda how much don't know till I get the wide O2 sensor (think I will just use a Micro controller from work with an ADC inpit (analogue in ) to display reading for now and think deeply about the MegaSquirt 3.
Thinking K1100 TB's next with this setup will be the next step.
Halo

Just brought some K1100 TB's for next mod Themason



Halo

Guys what about a cone filter straight off the afm

a few have done that already halo .....check out scheffers and a few other moders

good for fine weather riding i guess

i have something similar in mind but a bit more integral

Why?

1. The OEM filter got a very good capacity.

2. KN's and similar filters lets more crud through.

3. KN's and similar filters should be coated with oil,
usually some of this oil is drawn into the TB's and
collecting the before mentioned crud.

4. The area above the engine gets awfully hot,
the engine performs better with cool air.
The OEM setup pulls air from the front.

Halo, two clicks on an otherwise stock engine might be too much. Now that you have done that you have to change the setting of the potentiometer. This is equisitely sensitive and will take several tries to get right. The idle tells me you need to adjust the bypass screw on the air flow meter (tough bugger to get at when in place, you need a short ball end 5 mm socket, but not too short). Were it me I would only go one click on that spring.

Something I like to do is take the bike to a car repair shop with a five gas analyzer to check my idle mixture. It should be 2% CO at idle. Judge where you go from there. Have fun and keep us posted.

Stick with the stock air box. The little cone filter off the back of the AFM is bs. What does work is to replace the small stock K100/K75 intake snorkel with one from a K1100. On RSs and RTs this requires some carving on the side vents to make room for it. On unfaired bikes there is nothing in the way. You can find images of them at Beemerboneyard or at Fleabay.

Yep, have to wait for the wife to fall asleep so your snoring doesn't keep here awake all night! Never happens to me, mind you, heh, heh, heh. Much.

So Themason this is what I want to do I have been thinking of a way to make both camps happy and this is it. I propose using a MAP sensor pinched from the Megasquirt apps and then feed this into the dev system board (look my 84 thread) then drive a digital pot (via I2c or SPI) and simulate the AFM and feed back into the LE jetronic so it doesn't know any different. This way I stay with the (analogue beautiful FI heart and then I can get the airflow moving better than having that flap there (it's a real no no). Now honestly the mod to the AFM so far is great I have been caning the bike today and it rocks now, the staintune exhaust that is on her has made the difference greater I am sure, and it even sounds loader now than before, Imagine getting rid of the AFM all together. To cal the MAP sensor just put it inline with the AFM and take measurements on both sensors across the complete throttle range and then use the MAP values into the micro controller and supply on the output the appropiate resistance (which translates to a voltage to the LE jetronic FI unit)
The temp sensor must be kept as the MAP requires to truely emulate the AFM,s function so will be extracted or replace with an after market one.

Where do I put the vacum sensor as it cannot be be at a spot where it is port driven but must be directly of the TB,s or inlet manifold
Halo

Bosch dumped D-Jetronic for a good reason. Reading MAP as your primary determinant of injector pulse width is unreliable, particularly in higher performance engines. D-jet is unable to accomdate high performance cams and runs extremely rich at idle due to the low idle vacuum and the strong variations in idle vacuum typical of cams with any kind of overlap. The 284 degree cams in our K bikes use pretty aggressive cam timing by the standards of stock motorcycles. A set of race cams for a V-Rod use 257 degrees of intake timing and 260 degrees of exhaust timing, both at 1 mm lift. The stock V-Rod cams use about 230 degrees of duration at 1 mm lift. Our bikes have cams with 284 degrees of duration. D-Jet could not cope with that and is the reason it was replaced with L-Jet. I don't see how this system, which uses MAP like D-Jet will be able to do any better. The damping chamber and inertia of that vane allows L-Jet to accomdate high performance engine mods that D-Jet could not and is the reason L-Jet replaced D-Jet

MAP sensors are ok for trimming basic airflow information, much as your NTCII sensor does. Harley Davidson's Delphi manufactured engine management has a MAP sensor, but basic pulse width is determined by throttle position and crank position and speed.

The ideal air flow measuring device in my mind is the later hot wire system, but the relationship between air flow and output voltage of a hot wire AFM and one with a vane are inverted, making it impossible to use a hot wire AFM with a computer designed for a vane style AFM.

Thanks Themason good info I suggest the MAF sensor, as prevously stated with an addition micro controller I can just invert the MAF response for the LJet. Essentially think of the additional black box between the MAF and LJet AFM input as being a translated LJet conversion. Which MAF sensors are best/less restrictive( the probe type ?) Any good older car type, we have a wreckers here that cost 5$ for any bit from any car for something like that.
Logical now to look at the excellent Megasquirt info on their recommendation for MAF sensors and suggested implantation.
Remember what I am proposing is not rocket science, I'm not designing a fuel injection system just emulating a sensor.

Halo

I guess I do not understand why you would use a MAF sensor when Bosch abandoned that type of air flow meter for good technical reasons? L-Jet is better than a MAF based fuel injection.

MAF Mass Air Flow sensor that is what the barndoor is on an L Jetronic system maybe you mean MAP as for Manifold Absolute Pressure which I will say is a bit agricutural by the standards of today.

Rick G advice please I'm good at the electronics but I need to pick a better sensor don't care which one just one that will restrict the air flow less than the current one I'm interested in tricking the FI to thinking it's still connected to the AFM pot

The MAF sensor from a BMW318i E30 with the M40 engine or 320i with the M20 six.
They both are around 2 lts and spin up to 7000rpm.
Link to E30 318i M40 http://realoem.com/bmw/showparts.do?model=AJ51&mospid=47273&btnr=13_1330&hg=13&fg=15
Very similar in operation and size. Not sure if they were L Jetronic but were an analogue system and Bosch.
There probably be a heap of european cars that used the same thing.
I don't know much about the GM cars but Fords of that era in Oz used the D Jetronic type of system on the six cylinder models

Rick thats an afm type not maf

Oh looked at this and explains two types flap and hot wire I was thinking of the hotwire type as states on the link less air resistence
http://www.howrah.org/air-flow-sensor.html

The two common types are hot film and barndoor which is self explanatory.
This forum was the first place I saw a MAF sensor refered to as an AFM.
I am not sure if the hot film would be able to be used by an L Jetronic AFAIK they are only used with a digital system.

Is there a fixed setting for this bypass screw?

The relationship between the output voltage of the air volume determinator or air flow meter, whatever term you choose for it, and air volume through the device is opposite for hot wire AFMs and vane style AFMs, meaning you cannot use a hot wire AFM with an ECM intended for a vane style AFM. I looked into that many years ago.

The bypass screw on the air volume determinator is adjustable so the correct idle mixture can be set. Factory settings call for an idle CO reading of 2% plus or minus 0.5%. A one-gas analyzer that reads CO, such as the Gastester Digital, may be used to set idle CO with the bypass screw.

Themason wrote:The relationship between the output voltage of the air volume determinator or air flow meter, whatever term you choose for it, and air volume through the device is opposite for hot wire AFMs and vane style AFMs, meaning you cannot use a hot wire AFM with an ECM intended for a vane style AFM. I looked into that many years ago.

Sorry I think you still dont understand my concept Themason , I can create a black box that does the magic that sits between the hot wire sensor and the Ljet FI unit that will do the inversion
Halo

[quote="Halo"][quote="Themason"]The relationship between the output voltage of the air volume determinator or air flow meter, whatever term you choose for it, and air volume through the device is opposite for hot wire AFMs and vane style AFMs, meaning you cannot use a hot wire AFM with an ECM intended for a vane style AFM. I looked into that many years ago.[/quote]
Sorry I think you still dont understand my concept Themason , I can create a black box that does the magic that sits between the hot wire sensor and the Ljet FI unit that will do the inversion
Halo
[/quote]

What is the voltage change for each type of air volume determinator? Is the change in voltage with respect to air mass linear, logarithmic or exponential? Is it the same for both methods of measuring air mass? How do you compensate for the overswing enrichment present in L-Jet that you loose with a hot wire system unless you can read throttle position and rate of change directly for all throttle positions? That is essential to make a hot wire system work, but the L-Jet computer has no means to make this calculation. Overswing of the vane during abrupt throttle openings works like an accelerator pump on L-Jet.

Themason wrote:

Halo wrote:

Themason wrote:The relationship between the output voltage of the air volume determinator or air flow meter, whatever term you choose for it, and air volume through the device is opposite for hot wire AFMs and vane style AFMs, meaning you cannot use a hot wire AFM with an ECM intended for a vane style AFM. I looked into that many years ago.

Sorry I think you still dont understand my concept Themason , I can create a black box that does the magic that sits between the hot wire sensor and the Ljet FI unit that will do the inversion
Halo

What is the voltage change for each type of air volume determinator? Is the change in voltage with respect to air mass linear, logarithmic or exponential? Is it the same for both methods of measuring air mass? How do you compensate for the overswing enrichment present in L-Jet that you loose with a hot wire system unless you can read throttle position and rate of change directly for all throttle positions? That is essential to make a hot wire system work, but the L-Jet computer has no means to make this calculation. Overswing of the vane during abrupt throttle openings works like an accelerator pump on L-Jet.

What is the voltage change for each type :- Don't care it's just a reading at an air flow rate
What is the change in voltage with respect to air mass, linear, log or expo :- Again dont really care it's just a reading just like all other sensors I use at work.
Is it the same for both types :- Again don't really care just need to know what it is.
Compensation for over swing :- Please expand but worse case it's just another input to measure, remember I am feeding my conditioner just into the Ljet AFM sensor input the Ljet still makes it's own decisions based on all it's sensor readings, it knows the throttle position already. I am just making a sensor black box conditioning circuit to trick the LJet to think it's still connected to the flap type AFM, not a EFI unit.
Works like this
Plug little black box into the original AFM and the new hot wire type (both are in series) on the bike
Decode the revs and run the black box computer to give very fast commer delimited data to a files on the EXACT reading of each sensor at each rpm readings.
Take data and import into windows excel, plot RPM vs Voltage reading for both AFM's compute the formula from the results and you have your algorithm for your lookup equilivelant for the black box computer
Then plug the black box in between the hot wire MAF and the LJet FI unit and when I rev the bike, all I have to do is Supply the original AFM value to the Ljet input for the AFM
I do this sort of stuff all the time at work with sensors we use in our monitor equipment designs.
Halo

What Halo is proposing is an active circuit that can, not only, invert the relationship between air volume and sensor output voltage, but also potentially alter the response linearity (linear versus exponential). This could be accomplished with an Arduino as the base of the converter. The programability of the device allows it to adapt a variety of modern air volume determination methods to the analog expectations of the L-jet. It will also be able to program delays into the signal processing to simulate inertial sluggishness in response, and a variety of other "real world" anomalies. It is an interesting concept and possibly an exciting project to complete.

Thanks Robmack yes I agree if it wasn't exciting I couldn't be bothered with it but potentially it could be as simple as saying take this sensor from this BMW old car type worth nothing, plug this in between and presto, worst case for each bike a learning mode setup first.
Could also use much more powerful arm 7 dual core cpu as well we have heaps of dev systems just sitting around however to keep this open source and easy best to look at the larger arduino offering first so others could try.
Robmack
But all this stuff is still open loop taking a wide O2 sensor output and feeding back into the black box for suttle changes would be interesting as well (closed loop response system)
Halo

Well dev system purchased went with the USBDriod as has host mode for connection to my samsung note phone via usb cable

These are the dimentions of the 320i MAF sensor

Thanks Rick what year is it (this is the hot wire type right ?) just that I want to go to pick a part tomm to pick one up they actually have a 2005 325ci down there at present and a 1993 318 and a 1990 525
any of those any good?

It's a E36 4/94 320i It has an M50.B20 engine.
On real OEM it looks like the E36 with an M52 engine will also do the job but has a different part number so may have different values. The E36 318i have the barn door type.
The E36 323, 325 and 328 seem to have what looks like identical but again with different part numbers.
E36 is body shape from 91 to 99.
M50 is early six to 7/94 then M52.
B20 is 2 ltr B25is either 2.3 or 2.5 ltr and B28 is 2.8ltr.
Next model is E46 and it has M52 engine with the same B variants and the engine electronics were much the same through to 2006 so some of those will fit the bill.
Many of the 5 series with the six cylinder wer the same engines

Great thanks Rick great advice the ones at the wreckers may do then I have found similar in my looking to you. Can you tell me what the diameter of the K AFM is?
You can get new ones from 120$ onwards but pick apart will be 20$
Halo

I definitely know my place....!

The outlet of the MAF is 60mm but the inlet to the plenum is 72mm which would lend itself to having the new sensor coming directly of that and across the frame then with an elbow back to an air filter and you would have heaps of room left in where the original filter was. Just think how easy it would be to get to the back of the TBs. It may even possible with a bit of refitting to have the original filter.

.

So we could go 72mm MAF (closest down from like the 70mm one you propose Rick) , and then I was reading about aiir flow,friction, air pressure/densities etc and the go in my mind now is to get the fresh air (cooler/denser) air from front using the same diameter silicon (low internal friction type we don't want to adversely heat the air along the way to the MAF) up front then(and I know that there's mixed views on this one but) high flow k&n with one of those dry filter covers they use with them (splash proof but not that restrictive)
Then there's the traditional mod like you mentioned with the original airbox, but we need to test first, I have just reverse engineered the brivis huge fan coolers motor controller I was given so I could use that now with the unit to or blow very larger air volumes

I wonder how much hotter it really gets if you suck air right off the back of the MAF I have usb temperature data loggers at work that are small I propose to measure with one at the back where the MAF would be and up front where I propose we suck air from and look at the difference (temperature differential) there was talk that if you find a pressured air section somewhere on your car you can get denser and cooler air for example wheel wheels on cars.
Oh and high AJAY hope all is well matey

I know that I am maybe getting a bit ahead here than need be but the K100 plennum and long curved ram tubes combined with the shape and position of the plennum inlet being well to the front of the TBs all this makes for a very disturbed airflow as it goes down to the inlet valves. I feel that if you are looking for good airflow there needs to be a lot of work put into the plennum area before the big increase in size of the MAF sensor will have any big effect.
I don't think you should let the limitations in that area hold you back from doing anything and I would say that if a better airflow can be achieved it will be good icing on the cake.
It is hard to get a really good flow path in the limited area but I feel that an improvement can be made when the filter space can be utilized better due to the air being drawn from outside that hot area.
The 70mm MAF is quite big enough to support a 2 ltr engine at 7000rpm. Basicly with a 4 cylinder engine only 2 cylinders are drawing air at the same time and all that requires is that the inlet to the MAF be 1.5 times the diameter of the individual TBs. The K1100 TBs are 36mm so that works out at 54mm. So 70mm which is the external Diameter of the MAF and internal would be close to 65mm is way big enough to feed the engine.
Like I was saying the real big improvement in breathing will be in redesigning the plennum but I think that should be left for another day.

Wow fantastic advice and information Rick yes i agree totally. Tommorrow then
Halo

No Halo, L-Jetronic does not use throttle position to determine pulse width during normal running. The TPS on an L-Jet system has only two switches, one for full throttle and one for close throttle. There is additional enrichement at each positon. Otherwise, there is no TPS input and you can run the bike with no TPS. In fact, for winter riding in Germany on snow their R&D Techs disconnected the TPS to defeat the closed throttle fuel cut off and smooth throttle response at small throttle openings and low rpms.

If you ever dyno one of these engines with the TPS disconnected and measure the air/fuel ratio across the rpm range you see the reason for idle enrichment and for full throttle enrichment. For the rest of the rpm range, from 2000 - 8000 rpm, if idle CO is set at 2% or very close the AFM from L-Jet is a dead flat line at about 13.9 : 1. In other words perfect [i]for power[/i]. Even with bigger TBs and porting it will do this for you. Good luck doing as well with what you are doing. I have tried tuning digital systems and it is much more time consuming, and it is darn difficult to get a nice flat AFR across the rev range.

About overswing. On a digital system, you have to have a TPS that reads throttle positon across all throttle movement, not the TPS used by L-Jet. The computer has to be able to measure not just throttle position, but how rapidly it is opened, angular speed. This is necessary to calculate the extra fuel required for acceleration. You need more than just absolute airflow but change in airflow, or indirectly change in throttle position. The computer used in L-Jet, D-Jet or any MAP based air flow measuring fuel injection does not have this capability. Instead, overswing of the vane in L-Jet when the throttle is whacked open hard generates the signal to add fuel rapidly in response to hard acceleration.

What has me shaking my head about all of this is that techs who make really fast K bikes ditch Motronic in favor of L-Jet because if you are not concerned with emissions or mileage, L-Jet works so much better than the newer systems. You are going backwards.

Yes thanks Themason for the information good as always.
Think of it as using the hot Air MAF through my Processor to the Ljet to tell it absolute air volume and on full throttle giving the Ljet the same reading that the flap/vane AFM would.
Halo

Well Rick all the BMW air flow meters were gone from pick a part wreckers so I purchased this liberty (subaru) 1997 MAF sensor is a 72mm internal diameter(looks very little restrictions), play time on the weekend. Wonder how hard to find the pinout will be, or if it's the voltage out or PWM (pulse width modulated) I can handle both. Or if I will have to open her up to get the connection worked out
Halo

Well Rick, Robmack & Themason I had some success with the MAF sensor, Initially I was concerned with the lack of information on the MAF I picked, really wanted to know if it was the analogue voltage out or Pulse Width Modulated type. So I opened her up and looked up the chipset on my phone








The sensor has a Hot wire and Temp sensor and I was hoping the temp was internally calibrated via the circuit there rather than by the EFI ECU inwhich I would have to compensate with my processor. The circuit board is typical for automotive a ceramic substrate hybrid circuit that has great thermals, the circuit IC ends up being a quad opamp therefore the output is purely analogue voltage, thats a plus.
As there is four operational amplifiers this also means without having to reverse engineer that the temperature sensor is supplying local closed loop feedback to the air flow sensor for temperature compensation, so it;s all handled internally real plus.
The device is high quality from Japan even with the output signal being well separately shielded. Remember only earth shields at one end to stop ground loops.

Testing the sensor by just blowing into it shows the voltage deviation (excursion) just perfect for the processor after level translated to 0 - 5V. What really surprised me was how fast the sensor reacted Rick to the pressure change must be massively more sensitive than the barn door AFM type.



All in all Rick, Robmack and Themason I scored well for $40 from the local wrecking yard and it's all on the arduino dev board now that the easy bit is done.
Halo

good going halo ...nice win ..

that chip looks typical of many of the quad op amps available just about everywhere "lm 324" rings a bell as well as all the tlo74 - 84 series