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Thread: Speeduino 2T EFI Project

  1. #151
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    Quote Originally Posted by ceci View Post
    I know I'm wrong, but I still think that taking the pressure of the crankcase through a hole located below the exhaust port and controlled by the skirt of the piston, is a simpler method that will allow us to know how much is the quantity aspirate
    Maybe wrong, or maybe not. It is a good idea for a timed pressure reading and worth looking at. I will find the series of EngMod crankcase pressure simulations I ran and have a look.

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    At 9,000 rpm they look much the same at 0.8 bar and at 12,000 rpm they range from 0.7 to 0.85 bar. So might be able to work as an indicator of air flow.

    For myself I still think the variance between maximum and minimum pressure each cycle gives more definition and is the approach I am going to try first.


  2. #152
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    Quote Originally Posted by husaberg View Post
    One more piece i just found the KTM has a lambda in the pipe Attachment 339815
    That is interesting, KTM have located the O2 sensor in the header, the ideal place for a four stroke. But conventional two stroke wisdom has it in the rear cone or stinger for a more effective reading and less risk of oil contamination. In a two strokes header it is possibly going to see a diet of raw oxygen spilled from the cylinder before the exhaust port closes and then hot combustion products. A confusing mixture that can appear lean when its not.

    As the response time for an O2 sensor is quite long compared to the cycle time at higher rpm the signal must become confused about what its looking at. The tail pipe position gives a better average reading and also responds quickly enough. I think KTM has fallen into the trap of trying to apply four stroke thinking to a two stroke. I believe KTM copied Flettners "B" port injection concept but he did not use an O2 sensor. So who were they going to copy for that, probably 4 strokes of course.


  3. #153
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    Quote Originally Posted by TZ350 View Post
    That is interesting, KTM have located the O2 sensor in the header, the ideal place for a four stroke. But conventional two stroke wisdom has it in the rear cone or stinger for a more effective reading and less risk of oil contamination. In two strokes header it is possibly going to see a diet of raw oxygen spilled from the cylinder before the exhaust port closes and then hot combustion products. A confusing mixture. As the response time for an O2 sensor is quite long compared to the cycle time at higher rpm the signal must become confused about what its looking at. The tail pipe position gives a better average reading and also responds quickly enough. I think KTM may have fallen into the trap of trying to apply four stroke thinking to a two stroke.
    Not only is it in a 4t postiion its the same sensor used in the 4ts and bloody expensive with it
    It would be $679NZD based on the AUS price
    Year Model Fiche Section
    Year Model Fiche Section



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  4. #154
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    Click image for larger version. 

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    For a two stroke this is a better position in the rear cone for a O2 sensor than KTM's position in the header. I am not sure but Wobbly may even put his O2 sensor in the Stinger itself.


  5. #155
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    Quote Originally Posted by TZ350 View Post
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    For a two stroke this is a better position in the rear cone for a O2 sensor than KTM's position in the header. I am not sure but Wobbly may even put his O2 sensor in the Stinger itself.
    I found two rules of thumbs on a net troll

    i suspect ktm is only using it as a trim for euro emissions possibly only idle and and using averages for basic trm rather than a constant data input.
    the main fueling will be based of a table and Map sensor
    Bell uses these figures for mixtures

    Starting 1:1-3
    Idling 1:8-10
    Low speed running 1:10-13
    Light load ordinary running 1:14-16
    Heavy load 1:12-14

    The numbers for a four stroke are as follows: (again, just recommendations for baseline tuning, exact numbers also depend on other factors)

    idle 14-15:1
    light load/low rpm 14-16:1
    light load/ordinary running 14-15:1
    heavy load 12-13.5:1

    On a four stroke, you can rely 100% on the afr for tuning. On a 2 stroke, the way the exhaust works, the air in the expansion chamber can be very turbulant at certain rpm and throttle ranges. When you use an AFR in a 2 stroke you will work off the averages rather than the exact. It is a great tool to keep an eye on where you are at, it is however 1 tool out of a whole arsenal that you can use to get the bike tune dialed in.

    I trust the gauge 100%, what I cannot trust is that with all the air moving and resonating around in the chamber, the readings may not be as accurate as in the 4 stroke engine. The wideband in the 2 stroke will likely not read very accurately near idle and in low throttle situations, so care must be taken to ensure proper running in those areas. You should also verify that the afr's you are seeing are corresponding with the plug readings and cylinder wash readings to make certain the bike is running as it should.It's a matter of where the sensor is placed in the exhaust stream.
    Two rules of thumb i found where
    The best spot on a two-stroke is from about 90% down the length of the header to the first 5% of the divergent cone. "Off-the-pipe" readings may be affected by A/F blow through, but anywhere within the usable power range, there should be very little chance of outside air being anywhere near the sensor at that point.
    To install you will need a 12v dc power source. The sensor must be heated before use, so the power source has to be able to run the wideband before the bike is running. The sensor should be places in the largest part of the expansion chamber, on the upper 3rd of the exhaust. The placement needs to be up high to keep from collecting oil.
    I prefer the second as the rest of what he said makes so much sense all the suff in the first paragraphs




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  6. #156
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    O2 sensor is often associated with EFI but Wobbly uses it for dialing in carb's too.

    Target Air/Fuel for a WOT power pull is 12.5:1 (lamba 0.85).

    Off the pipe I usually see 17:1 (lamba 1.2) because of the excess short circuiting, in the cylinder combustion is probably closer to a proper 13 - 14:1.


  7. #157
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    Quote Originally Posted by TZ350 View Post
    .
    O2 sensor is often associated with EFI but Wobbly uses it for dialing in carb's too.

    Target Air/Fuel for a WOT power pull is 12.5:1 (lamba 0.85).

    Off the pipe I usually see 17:1 (lamba 1.2) because of the excess short circuiting, in the cylinder combustion is probably closer to a proper 13 - 14:1.
    But wait these more
    The KTM 250 XC-W TPI system starts with the powerful and proven counterbalanced 250cc two-stroke engine. After years of two-stroke FI development, KTM found good performance, reliability, and (significant in Europe) the ability to meet Euro 4 emission standards with the patented “Transfer Port Injection” (TPI). The system starts with a 39mm Dell’Orto throttle body equipped with an idle adjusting screw and a separate cold-start device that opens a bypass to allow in extra air. Oil is supplied from the automatic oil pump and injected through the throttle body with the incoming air. The Dell’Orto throttle body does not house a fuel injector, as KTM found mounting two fuel injectors downstream into the rear transfer ports provides excellent atomization of the fuel with upstream air. The result is highly efficient combustion and reduced losses of unburned fuel.
    Knowing when and how much fuel to inject is all controlled by KTM’s engine management system (EMS). This system uses a newly developed electronic control unit along with five sensors that determine not only how much fuel but also how much oil to inject. You will recognize these sensors as: throttle position, coolant temperature, intake air temperature, intake air pressure, and ambient air pressure. Thanks to these sensors and the EMS, there is no longer the need to manually adjust the jetting for temperature or altitude conditions.

    Extra air for choke has to be a typo two pressure sensors it must be a double one on the oil pump two ports one as reference



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  8. #158
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    Quote Originally Posted by husaberg View Post
    ... two pressure sensors it must be a double one on the oil pump two ports one as reference
    "Ambient" .... to keep things in balance as you climb a mountain or the day clouds over and a cold front rolls in.

    "Crankcase" .... so as to see changes in air flow.

    That is my guess.

    I think a pressure sensor in the inlet tract itself would be pointless as there is not the sort of pressure variance there like you see in four strokes.


  9. #159
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    Quote Originally Posted by TZ350 View Post
    "Ambient" .... to keep things in balance as you climb a mountain or the day clouds over and a cold front rolls in.

    "Crankcase" .... so as to see changes in air flow.

    That is my guess.

    I think a pressure sensor in the inlet tract itself would be pointless as there is not the sort of pressure variance there like you see in four strokes.
    I wonder if all Map sensors see actually ambient pressure anyway as wouldn't they need it for a reference. inlet tract or Crankcase wouldn't they see the exact same pressure anyway other than a Disc Valve cylinder or if it was pre reed. sampling,Looking at the pics the air supply for the Map sensor is at the rear transfer position
    Edit i found this
    ANALOG MAP SENSORS
    The MAP sensor consists of two chambers separated by a flexible diaphragm. One chamber is the "reference air" (which may be sealed or vented to the outside air), and the other is the vacuum chamber which is connected to the intake manifold on the engine by a rubber hose or direct connection. The MAP sensor may be mounted on the firewall, inner fender or intake manifold.
    A pressure sensitive electronic circuit inside the MAP sensor monitors the movement of the diaphragm and generates a voltage signal that changes in proportion to pressure. This produces an analog voltage signal that typically ranges from 1 to 5 volts.
    Analog MAP sensors have a three-wire connector: ground, a 5-volt reference signal from the computer and the return signal. The output voltage usually increases when the throttle is opened and vacuum drops. A MAP sensor that reads 1 or 2 volts at idle may read 4.5 volts to 5 volts at wide open throttle. Output generally changes about 0.7 to 1.0 volts for every 5 inches Hg of change in vacuum.
    When the ignition key is first turned on, the powertrain control module (PCM) looks at the MAP sensor reading before the engine starts to determine the atmospheric (barometric) pressure. So in effect, the MAP sensor can serve double duty as a BARO sensor. The PCM then uses this information to adjust the air/fuel mixture to compensate for changes in air pressure due to elevation and/or weather. Some vehicles use a separate "baro" sensor for this purpose, while others use a combination sensor that measures both called a BMAP sensor.

    On turbocharged and supercharged engines, the situation is a little more complicated because under boost there may actually be positive pressure in the intake manifold. But the MAP sensor doesn't care because it just monitors the absolute pressure inside the intake manifold.
    A good MAP sensor should read barometric air pressure when the key is turned on before the engine starts. This value can be read on a scan tool and should be compared to the actual barometric pressure reading to see if they match. Your local weather channel or website should be able to tell you the current barometric pressure reading
    MAP SENSOR TESTS
    A MAP sensor can also be bench tested by applying vacuum to the vacuum port with a hand vacuum pump. With 5 volts to the reference wire, the output voltage of an analog MAP sensor should drop, and on a Ford digital MAP sensor the frequency should increase.
    An analog MAP sensor's voltage can also be read directly using a voltmeter or oscilloscope. A digital MAP sensor's frequency signal can be read with a DVOM if it has a frequency function, or an oscilloscope. The leads would be connected to the signal wire and ground.
    Warning: Do NOT use an ordinary voltmeter to check a Ford BP/MAP sensor because doing so can damage the electronics inside the sensor. This type of sensor can only be diagnosed with a DVOM that displays frequency, or a scope or scan tool.
    Another way to check out a Ford digital MAP sensor circuit is to input a "simulated" MAP sensor signal with a tester that can generate an adjustable frequency signal. Changing the frequency of the simulated signal should trick the computer into changing the fuel mixture (look for a change in the injector pulse width signal).
    No change would indicate a possible computer problem.
    The Ambient pressure sensor in the KTM can get confused if you change altitude quickly with the bike not running IE trucked on ute.
    To re-calibrate it needs to be stopped and started again.
    Its the only foible reported i have seen.


    I find the manual choke interesting though.It seems odd that given the bike has a temp input and a ECU it would need it.

    KTM have reported the TPI is only really a stop gap measure rather than a total solution as Euro 5 comes in soon and euro 6 is twice as tough again.
    They just cant get DI to work cheaply and as well HP wise.



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  10. #160
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    Quote Originally Posted by TZ350 View Post

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    At 9,000 rpm they look much the same at 0.8 bar and at 12,000 rpm they range from 0.7 to 0.85 bar. So might be able to work as an indicator of air flow.

    For myself I still think the variance between maximum and minimum pressure each cycle gives more definition and is the approach I am going to try first.


    What happens in the first graph 5%: the incoming gaseous mass barely has inertia because it is a slow and smooth displacement, in this case the piston creates vacuum faster, so the lowest pressure point is in the TDC where the piston stops creating vacuum.
    In the graph 65%: it is the reverse what happens and the lowest point of pressure is advanced to the TDC

  11. #161
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    Yes that makes sense.


  12. #162
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    When you let go of the accelerator: you cut the passage of the gaseous masses (creating turbulences that annul the inertia of this), but you do not reduce the inertia of the crankshaft and the linear speed of the piston.
    How it influences the minimum pressure point: delaying it (which is anomalous since the rpm places it advanced)

  13. #163
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    Just a thought dirty old 80's Turbo mods
    You could actually feed two imputs to the map sensor, Crankcase and Pipe output
    If you use correctly orientated check valves and a bleed and tees and Needle valves set up.
    You could contol the outputs from the Map to reflect when the engine is on the pipe or not.
    You could do this on the Fly on the Dyno or Track to vary the switching points to the two separate maps
    The Map can take multiple imputs as Turbo Maps do just this.
    Also using this method almost any Map sensor will do.
    You could do this with computer inputs but i feel this would be the quick and dirty for a proof on concept.
    It would be interesting to see what the out put signals would look like



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  14. #164
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    Click image for larger version. 

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    Starting to make some sensible progress. Interesting, the huge differences in AF ratio.

    Peak torque and therefor peak trapping efficiency is about 11,500 rpm and shows the richest mixture because there is the least short circuiting of air out the exhaust at that point.

    At 9.8 its still a little rich there though, should be more like 12.5:1. Have to be careful about the lean areas as some of that can be un-trapped air/fuel escaping out the exhaust port before its closed.

    I can see where the acceleration enrichment needs increasing. I am very happy with progress.

    When I have got back to the same level of tune as I had with the Ecotrons system I will start modifying the software code for Speedys firmware so as to get the style of MAP input I want.
    .


  15. #165
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    Quote Originally Posted by ceci View Post
    When you let go of the accelerator: you cut the passage of the gaseous masses (creating turbulences that annul the inertia of this), but you do not reduce the inertia of the crankshaft and the linear speed of the piston.
    How it influences the minimum pressure point: delaying it (which is anomalous since the rpm places it advanced)



    In addition to this, the pressure symmetry between the 150º and 210º points, which we see in the 5% and 15% graphs, reappears.

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