| Author | Message | ||
     Chrisrogers3 |
OK so I just installed my open airbox kit on my 12R. It is matched up with a K&N, Race ECM, and Jardine muffler. I know that a few reports out there say the bike will run lean BUT I am now getting a miss. It doesnt seem to be throughout the whole spectrum (at least not that I can notice) the miss seems to be at highway speeds near 3000 RPM. The bike has a lot better throttle response off the line, but on the top end it seems to be a bit of a dog now. Anyone else have issues like these? Any solutions or better air intake systems? Thanks | ||
| Xbullet |
it's gonna take it a minute to "relearn". i changed my plugs after going to open airbox only to find that my plugs were fine. after about 1000 miles of weirdness she now runs like a raped ape. run it between 3500 and 4000rpm for a hundred miles or so and then see how she does. mine didn't really jive until i did 100 miles at that constant rpm. good luck!! the efi on these bikes is finicky sometimes... (Message edited by xbullet on April 15, 2007) | ||
| Aj06bolt12r |
I second what bullet said, also my bike has an intermittent miss at light loads, like cruising at 60mph before it is totally warmd up. I think this is pretty much normal for there engines and dont worry about it. I dont know if thats what ur talkin about or not. | ||
| Tbowdre |
pretty sure the ecm learns in about 30 seconds? | ||
| Tx05xb12s |
I had the same issue, but these guys report the same thing I noticed. After taking her on a long ride at highway speeds, she purrs like a kitten with more power than ever before. | ||
| Ft_bstrd |
Mine stumbled a bit when I first put it on, but after a good run, it adapted just fine. I have no issues now. I am using the Race ECM. | ||
| Indy_bueller |
It only takes about 10 minutes running constantly over 3500 RPM if I remember correctly. | ||
| Chrisrogers3 |
Thanks for the help guys. I will give it a nice long run this weekend and see where it stands after that. | ||
| Captnemo |
Sounds like you got it and installed it. Run it like was stated above for the ECM's adaptive fuel to re-learn and you'll be golden. | ||
| M1combat |
It's "Adaptive Fuel Value", and it's right around 3500, not necessarily "above" 3500. | ||
| Deflaytedwayz2 |
i have a question about the open airbox. can i use the open airbox and not use a catch can? just let it recycle and burn threw the engine like stock? | ||
| Gentleman_jon |
I sure wish I knew what the real story is on the Buell fuel injection " learning" is. I have read everything from 10 seconds to a hundred miles. I have read everything from 3200 rpm to "just ride it as hard as you can". Anyone with FI experience like to explain what is really going on, and the best way to let the bike " learn"? Al Lighton, got your ears on? Thanks | ||
| Glitch |
Dynamic Digital Fuel Injection The Basics of Buell's Electronic Fuel Injection System Buell's Dynamic Digital Fuel Injection (DDFI) enhances engine performance using advanced computer technology. A microprocessor inside the Electronic Control Module (ECM) makes hundreds of changes per second. Each adjustment allows precise fuel and ignition mapping to the Buell powerplant for the current environmental conditions. The speed that the system can change the fuel & spark delivery to the Buell powerplant is incredible. The Buell DDFI can make hundreds of changes per second. Benefits of this system include an improvement in midrange power, easy cold starts and onboard diagnostic capability. This system also compensates for altitude changes. The DDFI system uses several sensors to provide feedback about external and internal operating conditions to the electronic "brain" of the system, or ECM. These conditions include: Rider input (throttle position) Engine load External environmental conditions (outside air temperature) Internal engine environment (cylinder head temperature) Each of these conditions must be known in addition to the information already "memorized" by the ECM. This is necessary for the ECM to perform the calculations necessary to deliver the optimum spark advance and fuel amount for each engine cycle for maximum performance as well as to meet government regulations for emissions. The method of how the required amount of fuel for any combustion cycle is calculated depends on the type of the EFI system. The three types of EFI systems are open loop, closed loop and combination open/closed loop systems. The first type of EFI system operates as an OPEN LOOP system. The ECM calculates and delivers spark and fuel based on a set of predetermined spark and fuel "maps." These "maps" provide the base information necessary to run the engine with only minor adjustments for external/internal environmental conditions. This method is accurate to the degree that the "maps" are accurate. The Harley-Davidson systems are open loop. The second type of EFI system operates as a CLOSED LOOP system. This system not only uses spark and fuel "maps" but also feedback from an exhaust gas oxygen (O2) sensor to continually adjust the amount of fuel delivered. This offers the advantage of "learning" the behavior of the engine over time as well as responding to a wider variety of conditions encountered while riding than that of an OPEN LOOP system. The Buell DDFI operates both as an OPEN and CLOSED LOOP system. This is necessary to adjust for all possible operating conditions. Buell's selection of high lift cams (which enhance engine performance) make it necessary for an open loop system at idle and wide-open throttle. Furthermore, when operating in open loop during cold start and idle, the system will utilize programmed fuel and spark maps in the ECM for ease of cold starting and to provide a stable idle. When the bike is at a steady cruising speed and operated under a light load, the DDFI system switches to closed loop operation. The system then continuously "tunes" the performance of the engine to compensate for changing conditions and provide maximum performance by using the O2 sensors input. General operating parameters for open and closed loop running. Return to Menu OPEN LOOP Idle and starting slow speeds under 20mph (1500 rpm) High speeds above 60mph (4,000 rpm) accelerating from low speed accelerating from high speed decelerating CLOSED LOOP Cruising between 40 - 60 mph at operating temp. (1500 to 3500 rpm) How does the Buell DDFI system work? Return to Menu The ECM uses six different sensors to monitor rider demands and changing engine conditions to determine the correct fuel and spark requirements. These sensors are: Throttle Position (TP) Sensor Cam Position (CMP) Sensor Intake Air Temperature (IAT) Sensor Engine Temperature (ET) Sensor Oxygen (O2) Sensor Bank Angle Sensor (BAS) The ECM needs the information from the TP and CMP sensors to calculate how much air is entering the engine. The TP sensor is attached to the throttle shaft on the left side of the throttle body. The CMP sensor is located in the gearcase cover on the right side of the engine. The TP monitors the amount of air entering the engine, by how far the throttle is open, whether it is opening or closing and how fast it is opening or closing. The ET Sensor provides the ECM the current engine temperature. Proper fuel and spark delivery are dependent on the temperature of the engine. The ECM will provide a richer fuel mixture on start up and a higher degree of spark advance. As the vehicle warms up to operating temperature the fuel mixture will lean and spark advance will decrease. The IAT sensor, mounted in the Helmholz Volume Power System (HVPS) air box, measures the temperature of the air entering the engine, when combined with the TP and CMP data the ECM can determine the density of the air entering the engine. The ECM also monitors the CMP sensor to determine the exact position of both cylinders in the combustion cycle and the engine speed. The fifth sensor is the Oxygen Sensor (02). It is desirable to operate the engine at or near stoichiometric, or approximately 14.6 parts air to one part fuel. The inclusion of the 02 sensor allows the ECM to ensure a proper air/fuel mixture is delivered to the engine by monitoring the final combustion efficiency in the exhaust system. This ensures optimum engine performance at any altitude. The sixth input is the Bank Angle Sensor (BAS). This sensor provides the input to the ECM that the vehicle is not leaning greater than a 55 degree lean angle. If the vehicle exceeds a 55 degree lean angle the BAS will interrupt the operation of the ignition system and the fuel supply. How does the O2 sensor measure the fuel mixture? Return to Menu An Oxygen sensor is a chemical generator. It is constantly making a comparison between the Oxygen inside the exhaust system and air outside the engine. A Zirconium stabilized yttrium oxide ceramic shell is coated with a layer of platinum. When the nose is heated the platinum will begin to react with the exhaust gasses and a voltage potential will form between the inner and outer layers. The sensor does not begin to generate it's full output until it reaches about 600 degrees F. Prior to this time the sensor is not conductive. This voltage output of the sensor is usually between 0 and 1.1 volts. A rich mixture leave very little free oxygen and the reaction will send out a voltage greater than 0.45 volts. If the engine is running lean, all fuel is burned, and the extra oxygen leaves the cylinder and flows into the exhaust. In this case, the sensor voltage goes lower than 0.45 volts. Usually the output range seen seen is 0.2 to 0.7 volts. The mid point is about 0.45 volts. This is neither rich nor lean. A fully warm O2 sensor will not spend any time at 0.45 volts. The O2 sensor is constantly in a state of transition between high and low voltage. Manufacturers call this crossing of the 0.45 volt mark O2 cross counts. The higher the number of O2 cross counts, the better the sensor and other parts of the computer control system are working. It is important to remember that the O2 sensor is comparing the amount of oxygen inside and outside the engine. If the outside of the sensor should become blocked, or coated with oil, this comparison is not possible. Also if the exhaust side of the sensor has been contaminated by using leaded fuels or gasket sealers which are not specifically identified as being approved for use with oxygen sensors the sensor can be permanently damaged. ADAPTIVE FUEL VALUE Return to Menu The Buell DDFI system has the ability to “learn” the engine fuel mixture needs. When the motorcycle is running in the closed loop mode and operated in a specific engine speed and load range, the system will compare the feedback from the O2 sensor to the base programming stored in the ECM. If a difference in these values is detected, the ECM will recalibrate the system program to compensate. This correction is termed the adaptive fuel value or AFV. This compensation value allows the system to adjust to different altitudes, air densities, and to some degree engine variations and wear. The normal AFV ranges based on altitude are between 85 and 115. The higher values are found at lower altitudes and the lower values at higher altitudes. The AFV correction is only applied to the fuel mixture during OPEN loop operation. During closed loop operation the O2 sensor signal is the primary compensation method. The AFV will be learned when the bike is operated at engine speeds between 2500 and 3500 rpm at road speeds in the 40 to 60 mph range under a steady light load (no down grades or steep upgrades, decelerating or accelerating) for 2 to 3 minutes. The AFV can also be reset to 100 by using the scanalizer at any time. The AFV value can be a valuable diagnostic tool. Compare the AFV values of bikes in your area which are running fine during routine services. When you are working on a bike which may have a DDFI problem, compare the values. If the AFV is higher than normal, the system is trying to correct for a situation which is causing the mixture to be too lean. Look for intake manifold or injector O-ring air leaks, incorrect ignition timing and TPS zero setting, low fuel pressure or a fuel line restriction as well as a sensor malfunction. If the AFV is lower than normal, the system is trying to correct for a situation which is causing the mixture to be too rich. Look for incorrect ignition timing and TPS zero setting, high fuel pressure or a leaking injector as well as a sensor malfunction. The O2 sensor can also cause the AFV to be set incorrectly. Internal shorts in the lead, poor electrical contact with the exhaust system or contamination can all affect sensor performance. O2 SENSORS CAN BE CONTAMINATED BY SILICONE SEALERS!!! ONLY USE SEALERS WHICH ARE LABELED O2 SENSOR SAFE IN ANY LOCATION WERE THE VAPORS CAN COME IN CONTACT WITH THE SENSOR. (top end of engine) IGNITION SYSTEM TIMING ADJUSTMENT - Cam position sensor adjustment (section 1.23 in 99/00 X1 service manual) Return to Menu The adjustment of the CMP sensor will effect fuel ratios and ignition timing over the full operating range. With the breakout box installed at the gray connector at the module, measure the voltage at pins 3 and 8 in the gray section of the breakout box. When the front cylinder timing mark is centered in the inspection hole, loosen the plate and turn it counterclockwise until the voltage drops to 0 vdc. Now slowly turn the plate clockwise until the voltage shifts to 5 vdc and tighten the plate. Keep the two plate attachment screws snug when performing this adjustment to reduce play. Take your time, recheck, accuracy is important. THROTTLE POSITION SENSOR ADJUSTMENT - TPS ZERO (not required when resetting idle speeds after initial calibration) Return to Menu FROM PAGE 4 OF BULLETIN B-017- section 4.33C in the 99/00 X1 service manual Verify Throttle Position Zero Setting Back out idle screw until it no longer touches the throttle plate stop. Back out idle screw one to two additional turns. Visually confirm that the throttle plates are fully closed. Connect scanalyzer to data link connector [91] with cable (Part No. HD-42921). Turn the ignition/light key switch to IGNITION. Turn the handlebar mounted Engine Stop Switch to the RUN position(but do not start the engine). NOTE: Observe that step 4 uses the standard diagnostic application cartridge and NOT the recalibration cartridge used previously. Insert diagnostic application cartridge (Part No. B-41325-99) into scanalyzer. During the next few seconds, the Scanalyzer sequences through a series of screens that reflect a power-on self test, the system copyright, and then an attempt at communications with the ECM. Once communications is established, the Diagnostic Menu appears on the Scanalyzer data display. Press number “3” key (Data Monitor) on scanalyzer and scroll down to last screen which has 3 Throttle Position (TP) readings. a. Open throttle to wide open throttle (95-100% open on first scanalyzer TP reading) and release throttle, allowing it to snap shut. b. Record Throttle Position Sensor voltage reading from scanalyzer. c. Repeat steps a and b a total of 3 to 5 times, recording voltage reading after each. • If the readings differ by less than 0.02V, go to step g. • If the readings differ by 0.02V or more, go to Step d. d. Open the throttle then gently force the throttle closed. e. Record Throttle Position Sensor Voltage reading from scanalyzer. f. Repeat steps d and e a total of 3 to 5 times, recording the voltage reading after each. • If the readings differ by less than 0.02V, go to step g • If the readings differ by 0.02V or more, replace the throttle body and repeat procedure from Step 1. g. Select mode #7 on scanalyzer menu. Select #1 re-zero TPS. A “calibration successful” message will appear. h. Press the mode key to return to Options Data Screen. Scroll to TP degrees. Turn idle adjustment cable clockwise until TP degree reading reaches 5.8. Press the mode key and press #3 to return to the diagnostic menu. Disconnect the Scanalyzer and turn the Ignition/Light Key Switch to OFF or LOCK. Turn the handlebar mounted Engine Stop Switch to the OFF position. Reset Warm Idle Speed DDFI Changes Service Bulletin B-029 Return to Menu New Rev limit function: Incorporates a skip spark feature. Resulting in extreme "hit", "miss" engine restriction. The ECM will now utilize the cylinder head temp as part of the equation to alter spark and fuel delivery. The MY2000 1/2 DDFI ECM protects the engine from extended operation at or near its limits for engine speed and cylinder head temperature by reducing available power and flashing the engine light on the instruments. This reduction in power occurs in successive stages: a mild (soft) spark/no-spark pattern, and an aggressive (hard) spark/no-spark pattern. "Soft" limit (speed or temperature): The ECM initiates a mild spark/no-spark cut. The ECM will also flash the Check Engine Lamp (CEL) to alert the rider when the engine temperature has exceeded a "soft" limit. "Hard" limit (speed or temperature): The ECM initiates the aggressive spark/no-spark pattern. If the rider should operate the engine near the "soft" limit the ECM will begin a countdown. If the rider persists in operating the engine near this "soft" limit and the countdown expires, the ECM will begin to operate as if the "soft" and, after another countdown, "hard" limits had been exceeded. Previous models offered only over rev protection by restricting fuel and backed spark advance down to '0' advance, resulting in lower performance. The new ECM does not retro fit to earlier models (pre-2000 MY). Buell Service Bulletin B-029 Glossary of Terms: Return to Menu Bank Angle Sensor (BAS) The Bank Angle Sensor senses if the motorcycle exceeds a 55-degree lean angle. The ECM uses this signal to shut off both spark and fuel delivery. Cam Position Sensor (CMP) The Cam Position Sensor consists of a Hall-effect device, magnet and plate. The plate is mounted over a rotating cup ("rotor cup" attached to the end of the camshaft. As the rotor cup turns inside the gearcase, six asymmetric "teeth" on the rotor cup sequentially break the magnetic field between the magnet and the Hall-effect device. The edges of these teeth are cut to correspond to specific positions of the camshaft during the engine cycle such as TDC for the front cylinder. The output of the CMP sensor is used by the ECM to determine engine position and calculate engine speed. This method of measuring camshaft position provides accurate information on engine position down to zero engine speed. Electronic Control Module (ECM) The ECM receives signals from the ET, IAT, CMP, 02, TPS and BAS. The ECM contains all the information needed to provide the proper fuel and spark mapping sequentially and individually to the front and rear cylinders of the engine at the proper time. Engine Temperature Sensor (ET) The Engine Temperature Sensor is located on the rear cylinder head near the spark plug. This sensor sends a signal to the ECM proportional to the current engine temperature. Fuel Pressure Regulator Valve Located on the fuel pump inside the fuel tank. The fuel pressure regulator maintains a constant 49-PSI fuel supply to the fuel injectors. The unused fuel is relieved inside the fuel tank. Helmholz Volume Power System (HVPS) Helmholz was a scientist who developed theories on air and sound motions. The Buell air box uses Helmholz principles combining his theories with the tuning of the intake duct and also effectively controlling the acoustics inside the air box. The Helmholz Volume Power System allows a small chamber volume to simulate a large area in terms of air movement, enhancing the engine performance, while reducing unwanted frequencies. Induction Module The Induction Module is located between the two cylinder heads. The Induction Module consists of a (43mm) single bore throttle body and intake manifold. The throttle body contains the TP sensor, manual idle speed adjuster, throttle plate and linkage for the throttle cables. The intake manifold contains the fuel rail and two fuel injectors. There is one fuel rail connecting the feed line to the injectors. Excess fuel is relieved by the Fuel Pressure Regulator inside the fuel tank. Intake Air Temperature Sensor (IAT) Located inside the Helmholz Air Box, this sensor sends a signal to the ECM proportional to the temperature of the air entering the engine. Manual Idle Speed Adjuster The idle speed is adjusted manually by turning the screw located on the right side of the throttle body. Pulse Width Pulse width is the amount of time a fuel injector is held open by the ECM. It is usually measured in milliseconds. Relative Air Density Air density effects how much oxygen is present within it. Air density is dependent on altitude (atmospheric pressure), temperature and relative humidity. Cool, dry air at lower attitudes contains more oxygen than warm, moist air at high attitudes. Horsepower is directly related to air density. Returnless Fuel System The Buell DDFI System is a returnless system, i.e.; there is no fuel return line from the fuel rail to the fuel cell. If fuel pressure should ever exceed 49 PSI, the excess fuel pressure is relieved inside the fuel tank by the Fuel Pressure Regulator Valve. Single Fire Coil The ECM controls the independent, primary windings of the spark coil. The ECM is thus able to provide sequential and independent firing of the spark plugs. Stoichiometry | ||
| Gentleman_jon |
Hey Glitch - I think I have a headache. That is the most boring post since I, myself, posted my Official Lil Blackie Work Log, which caused a run on Excedrin at drugstores from coast to coast.  But just to show that I read the whole damn thing, and just so no one else has to, (not that they would anyway) here is the short answer to my question for those brothers who are slow readers. "The AFV will be learned when the bike is operated at engine speeds between 2500 and 3500 rpm at road speeds in the 40 to 60 mph range under a steady light load (no down grades or steep upgrades, decelerating or accelerating) for 2 to 3 minutes." So now we know. Thanks Dave. PS: This informative section does not mention which gear must be used. I always thought it was fifth. Hey, just a darn minute, you didn't make this all up, did you ? | ||
| Glitch |
The steady RPM is what's important, the ECM doesn't know or care what gear you're in, as long as you're in gear. There's no way in hell I could have come up with all that on my own, and it be boring  There would have been too many smart ass comments along the way if it had been me. I got it from an old e-mail, from Al, I think. The memory is the first thing to go...or I think that's what I was told, I don't remember.  | ||
| Thelumox |
i have had some of the same symptoms as above with my '06 uly. not actually a "miss" so much as a "weak" combustion cycle. it only happens near 3000 rpm at constant speed (closed loop operation). i believe that the O2 sensor is adjusting the mixture/spark timing like it is supposed to, causing the irregular combustion cycles. BTW i just installed a performance kit on a ducati. ECM/pipes/airbox. the O2 sensor went into the trash (now open loop). the bike just runs so much better than before. i wish i could do the same thing to the uly; get rid of the O2 sensor and its constant tampering with my engine until these things get a little better at doing their function. i'm done, and i feel better now. | ||
| Al_lighton |
That info was written by Dan Hurda, lead powertrain engineer at Buell, I'm pretty sure. However, it is quite old, and is a somewhat simplistic description of DDFI-1. DDFI-2, as use on the XB's, is a little bit more sophisticated. Learning also involves vehicle speed on DDFI-2. If the bike is up to temperature, and the operation is steady state, it only takes a couple minutes for the AFV to reacquire. The AFV is the average of a whole bunch of "instantaneous AFV" calculations, where the instantaneous AFV is the ratio of the injector duration obtained from the O2 sensor closed loop operation over the map calculated injector duration. We think. It really doesn't matter if it is or isn't, as that assumption on the way it works seems to yield an accurate working model. The "weak" combustion cycle model described above is exactly what I believe the gentle surge is when operating in steady state at 3000. It bothers some people, it bothers me not in the least. That closed loop operation where the system is hunting on 14.7:1 during cruise is EXACTLY why our bikes meet 2008 emissions and get 50-55 MPG. And when you REALLY need power, twist the wrist and it's always right there. Still, someone could make a fortune if they developed an O2 sensor that had it's non-linearity centered on 14:1 instead of 14.7:1. Al | ||
| Glitch |
Thanks Al  | ||
| Akbates21 |
Al you are wanting to make the air to fuel ratio a little richer in closed loop by having an O2 sensor centered on 14:1 instead of 14.7:1. If this is what you are wanting to do it is very simple. You need to just install a resistor in line with the sensor and you can bring it down as low as you desire. The real trick is to make the air to fuel ratio a little leaner. Because to do this you have to add voltage to the system and that is not the easiest task but can be accomplished with a mildly complex circuit. | ||
| Gentleman_jon |
Thanks Al. Anthony, That sounds interesting. Would you care to figure out just exactly what kind of resistor would be required, and how to install it? Inquiring minds want to know. | ||
| Chrisrogers3 |
Thanks for all the help guys. I put about 200 miles on it over the weekend and its running amazingly well. I am glad I went to the open airbox, it has made a noticable difference in the throttle response. Does anyone out there feel it is important to run it on the Dyno to see if or how lean it is running? | ||
| Akbates21 |
Jon, I can come up with some information for my senior electronics class in college i was trying to up the the ratio to about 16:1 to increase fuel mileage. (not on a motorcycle but on a car) The information that i came across says that best performance come from about 12:1 to 13:1 air to fuel ratio. Anything less is too rich and best fuel mileage come from about 16:1 to 17:1. Anything more and you will be too lean and seize the pistons. The reason O2 sensors are centered around 14.7:1 is because of emissions and something to do with the hydrogen content being too high if you go leaner and the carbon monoxide content being too high if you go richer. I will check the weekend and see if i can get all the numbers for you. But in essence all an oxygen sensor is just a battery that changes the amount of voltage it makes based on how much oxygen comes in contact with it. If i remember correctly our bikes have a single wire 02 sensor so you would just install the resistor in that wire. It will have to be a small resistor because the 02 sensor operates in millivolts. And the resistor will cause a voltage drop and make the computer think the motor is running lean and will compensate by richening the air to fuel mixture. You could even make it adjustable by installing a potentiometer. But like i said i will get you more details this weekend when i have the time to make some calculations. | ||
| Akbates21 |
okay guys so i got out of work a little early tonight and did some calculations. Before i give you this PLEASE UNDERSTAND THAT THIS IS NOT TESTED AND IS JUST CALCULATIONS it should be correct but someone who has access to a dyno i would appreciate testing this theory. All my calculations were based off of a standard one wire automotive oxygen sensor which ours seems to be consistent with. The computer is constantly adjust the AFR so that it receives a reading of .45 volts. Anything less and it adds more fuel because this notes a lean condition. Anything more and it reduces fuel because this notes a rich condition. I believe that we want an actual reading of about .5-.525 volts which means we need to lose about .05-.075 volts between our O2 sensor and the ecm. To do this we should need a 3 to 4 ohm resistor. I know this seems small but we are working with low voltage and low amperage so the resistance will also have to be low. ONCE AGAIN I STATE THIS IS JUST CALCULATED AND I COULD HAVE MADE A MISTAKE SO PLEASE CONFIRM THIS IS CORRECT BEFORE YOU DO THIS LONG TERM. I would greatly appreciate it if someone with a dyno would test this out. If you want to test this and need some help with it please send me a PM and i will help you anyway i can. (Message edited by akbates21 on April 26, 2007) | ||
| Jimmys |
Akbates21: 12:1 to 13:1 is the sweet spot for optimum performance at WOT on most cars (american V8's is what I play with). Stoichiometric ratio (14.7:1) is the ideal ratio where just enough air is utilized to burn off the fuel. Now in regards to your wanting to fake out the O2 sensor... In modern car ECU's there are Long Term and Short Term fuel trims which are used to constantly adjust the AFR to 14.7:1 under most driving conditions. The only way to FAKE out the O2 is to exceed these correction factors so they can no longer adjust the AFR. However once you achieve this, your SES light will be on probably as the OBD system will determine there is an issue w\ your O2. How it works on the Buell, I'm not sure but the Engine Strategy is from GM I believe, and I'm quite familiar with how they control things in their Automobile ECU's. Jimmy -> EE for 12 years designing Automotive electronics. (Message edited by JimmyS on April 26, 2007) | ||
| Al_lighton |
A minor correction. You wrote: "The computer is constantly adjust the AFR so that it receives a reading of .45 volts" Not quite. The ECM is constantly cycling the injector duration to cause the O2 voltage to cross .45V. It never actually holds it there, which would be quite impossible to do given the response curve of the O2 sensor. A typical narrowband sensor has a response that looks like this:  The ECM is constantly adjusting the injector duration to bounce the O2 voltage between the two knees of the curve. If one was to take an AC voltage reading on it, I suspect it would read somewhere arounce .45V, though. Al | ||
| Akbates21 |
Al, you are right it never actually reads .45v but is constantly bouncing from voltages below and above. I just trying to say the target for the ecm is .45v to make things simpler to understand. Jimmy, when you are talking long term and short term fuel trims are you still talking about a single 02 setup or multiple 02 setup because i stated this would only work on a single 02 setup. one thing i don't understand is you said i am tricking out the 02. what i am talking about is leaving the 02 in the system just the same as it is now but cutting the wire coming out of it and soldering a resistor into that wire and linearly shifting the graph that Al posted down ward to richen the AFR just slightly. This will still allow the 02 sensor to vary its output in the same manner that it does now it will just adjust the output slightly. Maybe I am all wrong here but this is something i worked on in college and discussed with multiple professors who have a Doctor's degree in Electrical Engineering and who had worked for the Big 3. I am not saying that what i said is totally correct but it is close and i quite a bit of research on the subject. | ||
| Freezerburn |
I think it would be a great project for those who have the time. Imagine a potentiometer with an economy mode and a performance mode...just twist that dial. I guess the ECM would have to do the relearn for each mode but I think it could be useful. I of course would have it always set on the performance mode. | ||
| Spatten1 |
Still, someone could make a fortune if they developed an O2 sensor that had it's non-linearity centered on 14:1 instead of 14.7:1. I used to use a box on cars that intercepted the O2 wire and dropped voltage slightly. We used it for natural gas conversions. It resulted in toggling slightly on the rich side of stoch. Worked really well. It used a brand specific algorithm that kept the system from creeping off the charts rich, and also prevented codes. | ||
| Billybob |
i was loking at a 07 sportster with fi it had 2 o2 sensors one for each cyl what kind of fi is that | ||
| Spatten1 |
It is due to the different running temps of the different cylinders. A hotter cylinder needs less fuel. The fuel demands of each cylinder are different, and can be regulated with individual O2 sensors and individual injectors. | ||
| Stevenknapp |
Maybe I am all wrong here but this is something i worked on in college and discussed with multiple professors who have a Doctor's degree in Electrical Engineering and who had worked for the Big 3. I am not saying that what i said is totally correct but it is close and i quite a bit of research on the subject. Few things I see that are flawed. Resistors only give voltage drops when there is current flowing. There isn't much current flowing from the O2, it's a very weak voltage source and the ECU input has a very high impedence. You'll get some drop, but it will be hard to make it precise. The O2 sensor isn't linear at all. It's basically a step function, see Al's graph. So the voltage shift is going to change the high and low voltage, but it's not going to change the A/F ratio where the step occurs. And that steep area is pretty unstable as far as A/F ratio to voltage. Quit thinking of a O2 as an analog sensor, the narrow band ones aren't. They are basically digital, and the ECU's goal is to keep the duty cycle high/low 50%. } | ||
| Typeone |
random thought, hope its not ridiculous... is the 4th pot on the TFi doing something similar to what you guys are talking about with this resistor? i've always been annoyed that there wasn't a way to tell which setting will properly 'fool' the 02 so you can make the necessary tweaks. skimming over these voltage readings made me wonder if there would be a way to get more info, set it correctly and leave it. (Message edited by typeone on April 26, 2007) | ||
| Spatten1 |
StevenKnapp is right on: To "fool the 02", which is really fooling the ECM, you have to toggle the 02 signal so the ECM thinks it is hunting right around Stoch. If it is a steady signal it will look rich or lean to the ECM and it will keep moving richer or leaner. That is what baffles me about the TFI on the Buell system, and makes me wonder if it can really work long term. I believe TFI is really designed for an open loop system. I might be wrong, and am interested in additional opinions/theories. |
