what is your end goal. switching pipes w/o bungs or just to eliminate them and their feedback.
two of those wires are the heater circuit. if it is O2, there is a diode trick to tell the ecm everything is honky-dory and biases the circuit at .5 volt. if they are lambda sensors, i do not know if the trick will work.
i will see if the info i have can be PM'd. this works for a car so a mc should be the same.

this is something i posted elsewhere that explains the process, still looking for the article O2 circuit modification.


One of the first mistakes people often make is to add a resistor to try and trick the ECM in see a lower valve for the sensor output. Sometimes, you will run across someone who says that “X” value resistor made his machine sing but that could be a fluke.Usually a ECM uses a mega-ohm ( the O2 sensor is a milli output high resistance devise) measuring circuit and this translates into no matter what resistance you add, the full sensor voltage will still be seen. You must remember that resistance does not drop voltage, it just limits current. Now before you get your panties in a bunch, if the ECM were to apply a fair load, then the resistance would certainly drop the voltage but this is not the case here.So the question is what to do? Well a diode is a one way valve so to speak and the pn junction does have a reliable voltage drop when biased on and current flows. There are many spec’s but usually it is around .5 volts. The ECM expects to see .45 volts so we are ballpark. You can try using a radio shack # 276-1141 diode or one of similar values in the output wire of the sensor. The banded end must face toward the ECM as this will allow the positive voltage flow from the sensor through the diode to the ECM. This voltage is middle of the road as far as rich/lean.

 

Im simply after shutting off the check engine light on the dash. I will be saving for a better tuner (TTS) but until then I am running a PC5 that i just got done auto tuning. the bike runs phenominally, i just hate that yellow light starring at me. I Guess its not that big of a deal. Thanks for your time and input.

 

the diode trick will not work on the lambda. however, there is a trick to fool the ecm using a voltage divider circuit which feeds a 1 volt signal. i never have done this one since they were not around when i was fooling with o2's. i do believe they have off the shelf ones available. a little black tape does wonders.

 

So what's the difference between an oxygen sensor and a "lambda sensor"?

Lambda is just the ratio between the metered AFR and stoich. (which is essentially what an O2 sensor does by sending a voltage above or below 0.5 VDC back to the ECM)

 

FYI to the OP:

Ever since HD got their asses handed to them from the EPA for modifying AFR's the whole industry has tightened up when it comes to the whole altered tune thing. You might remember all them piggyback tuners came with O2 eliminators in the recent past. After the EPA bitch-slap, hardly any of them. Granted they've also adopted different ways to trick the ECM into richening up the fuel (CANbus modification, standalone ECM) but O2 eliminators have gone by the wayside.

If you really wanna take matters into your own hands, there's a way to put a resistor in the sensing wires for the O2 sensor to trick the ECM into thinking the motor is cold and it says in open loop permanently because ultimately that's all an O2 eliminator is. This would allow the PC5 to do its job 100% of the time. Some heavy googling should result in answers in that regard.

 

The first step in the invention of the O2 sensor occurred in Germany in 1899, when Walter Nernst devised the Nernst cell. At temperatures higher than 620 degrees Fahrenheit, the ceramic cell was capable of transferring oxygen ions from the gas inside of the cell to outside gases, generating an electrical current whose magnitude was dependent on the difference in the oxygen concentration of the two gases. Modern vehicle O2 sensors work according to the same principles that the original Nernst cells did. A zirconia bulb lined with platinum facilitates the transfer of the oxygen ions between air inside the sensor and the exhaust gases that flow over it at temperatures higher than 600 degrees Fahrenheit

Lambda VS. AFR: What’s the Difference?

Lambda and AFR are two paths to the same destination–a well tuned engine. However, understanding the difference and applying it to tuning practices can save time and maximize efficiency when dealing with alternative fuels. To be clear, an engine doesn’t know the difference between AFR and Lambda. It’s simply two different terms that that tuners use to effectively impart the same measurement of air and fuel used in the engine’s combustion cycles. However, the vernacular distinction isn’t as casual as, say the similarity between “dollar” and “buck.” There are distinct advantages to using A/F or Lambda in certain situationsPrinciple of operation of a zirconium oxygen sensor The zirconium oxide oxygen sensor generates an output voltage signal from 40mV¸100mV to 0.7V¸1.0V. Output voltage signal range of a properly functioning oxygen sensor is up to ~950mV.
When oxygen content in the exhaust is low and the engine runs with an enriched mixture, the sensor will generate а high voltage signal 0.65V¸1V. In case of a high oxygen content in exhaust (lean mixture), the sensor generates a low voltage signal 40mV¸250mV.
Properly operating oxygen sensor starts to work only if its sensitive element has been heated to a temperature of at least 350 ºC. Then its outcome electrical resistance significantly decreases and it acquires the ability to alter the reference voltage coming from the onboard controller through a resistor with a constant electrical resistance. This reference voltage is 450mV for most of the onboard controllers. Such controller considers the oxygen sensor ready for use only when as a result of the heating of the sensor, it can change the voltage in range greater than ±150mV ~ ±250mV. Oxygen sensor reference voltage may have different values also. For example: for the onboard controllers made by Ford, is 0V, and for the onboard controller of Daimler-Chrysler, is 5V.
Onboard controller measures the output voltage signal referenced to the sensor’s signal ground. Oxygen sensor signal ground, depending on its structure, can be connected to a separate connector terminal of the sensor or it can be joined with the sensor housing and in this case, when the sensor is mounted it will automatically connect to the ground of the vehicle by a threaded coupling. In most of the cases the oxygen sensor signal "ground" is connected with a separate wire to the chassis ground. But there are engine management controllers in which this wire is connected to the source of the reference voltage. In such systems, the onboard controller measures the output voltage signal of the oxygen sensor referenced to the source of the reference voltage.
. Practically, when the engine is in a steady state, fuel mixture deviates from the stoichiometric in range ±2% ~ ±3% with frequency 1 ~ 2 times per second. Operation description of the titanium oxide oxygen sensor Output voltage signal range of the titanium oxide sensor is from 10mV¸100mV to 4V¸5V. In such sensor changes in the exhaust gases composition causes reduction of the sensor’s electrical resistance. The electrical resistance is high at low oxygen content in the exhaust gases (enriched fuel mixture) and rapidly reduces with the fuel mixture leaning. Furthermore, the sensor shuts the 5V reference voltage coming from the onboard controller through a resistor with a constant electrical resistance. Output signal of this type sensor reacts much faster to changes in the exhaust oxygen level in comparison to the reaction of the zirconium oxide sensor.Operation description of the wideband oxygen sensor
Output signal of the wideband oxygen sensor, unlike the sensors with two levels, provides information not only for the direction of variation of the fuel mixture composition, but to its numerical value. By analyzing the level of the output signal, the onboard controller reads the variation coefficient value of the fuel mixture composition, which in practice is the lambda coefficient. For the Bosch wideband sensors the sensitive element output voltage (black wire referenced to the yellow) varies depending on the exhaust oxygen content and on the electric current polarity flowing in the oxygen pump (red wire referenced to the yellow). The onboard controller generates electric current and supplies the oxygen pump, value and polarity of which provides keeping the sensitive element of the sensor to a set level (450mV).
If the engine runs with the stoichiometric fuel mixture, the onboard controller would have supplied the red wire with voltage equal to that of the yellow wire and the current flowing through the red conductor and oxygen pump of the sensor would be zero. When engine runs with leaned fuel mixture the onboard computer supplies the red wire with positive voltage referenced to the yellow wire and a positive polarity current starts to flow through the oxygen pump. When engine runs with enriched fuel mixture, the onboard controller changes the both the red wire voltage polarity and current polarity. Currents flowing through the oxygen pump, set by the onboard controller, depend on the value of the deviation of the fuel mixture from the stoichiometric.
A measurement resistor is connected in the oxygen probe circuit which voltage drop indicates the exhaust gases oxygen level. Unlike narrow band sensors that communicate to the computer by means of a voltage on a single wire, the wide band sensor uses two wires and signals the computer by means of a current flow. An air/fuel ratio of 14.7 to 1 (by weight), is considered to be the optimum air/fuel ratio. When the ratio is above this value, the current flows in one direction, and when it is below this value it flows in the other. When the air/fuel ratio is exactly 14.7 to 1, the current doesn't flow at all. In order to signal increasing rich or lean conditions, the current flow increases in ratio to how rich or lean the air/fuel ratio is. The two wires are called the current pump wires. The voltages on these current pump wires varies from manufacturer to manufacturer. One of the 2 current pump wires will have a voltage supplied to the sensor by the ECU. The other wire will be a return wire from the sensor to the ECU

So what is Lambda?Lambda, which is a Greek letter demonstrated by the symbol λ, represents all fuel’s stoichiometric value as 1.00. Lean conditions would represent a value higher than 1.00, and rich conditions are lower. These lean (higher) and rich (lower) values are calculated for the Lambda scale by dividing the observed A/F ratio with that particular fuel’s stoich. For example: a 12.8:1 observed reading with gasoline is divided by 14.7 to produce a .87 Lambda reading.
How is Lambda Calculated?
A wideband sensor calculates lambda by comparing the oxygen left in the exhaust to the sensor’s reference pump cell which is referencing stoich. This is why free air calibrationis paramount to correct sensor operation. Because the sensor reads oxygen content, it is impartial to the fuel type being used. If the engine is burning fuel at its specific stoichiometric ratio, all of the oxygen is consumed during combustion. When the sensor detects this stoichiometric condition (no oxygen in the exhaust flow), the lambda gauge will display 1.(A/F) ratio is calculated by dividing the pounds of air an engine inhales by the pounds of fuel delivered per hour to the engine.Perhaps the first big, unpronounceable word we ever encountered in a garage was “stoichiometric.” By definition, it’s the optimum mixture of air and fuel, and that formula changes for each type of fuel. For pump gasoline, scientists determined that 14.7 parts of Oxygen is needed for one pound of fuel to completely burn to the point where there is no leftover oxygen or fuel—only the normal byproducts of combustion that include water and carbon dioxide. Lamba and Alternative Fuel TuningLambda has long been used for tuning purposes in high-end race operations and the OEMs—especially in countries on the metric system. It never really started breaking into the domestic mind set until a new high-performance fuel became readily available at the pump. The solution to this problem is to simply use Lambda as your unit of measure since this does not change, regardless of the fuel or fuel blend being used. At the end of the day, you want to keep things consistent to make interpreting the data as easy as possible. A narrowband sensor will not communicate the necessary data . A narrowband sensor will only read richer or leaner than stoichiometric. A wideband will read the specific values in a much broader range. A narrowband reads a narrow range, richer or leaner than stoichiometric. A wideband will read the full spectrum. The widebands allows you to take measurements from .5 to 1.5 lambda. A wideband cannot pinpoint which fuel you are using because it is only reading the oxygen, or lack thereof. A wideband displays AFR by calculating the Lambda value by the stoichiometric ratio selected.

 

In the exotic car forums, I see this argument all the time..
I like AFR
Some like lam.
Maybe the difference between metric and SAE is a good illustration.
I am pretty sure my AFR gauge offered me the option of which numbers i would like to read it in.

 

this might sound like a dumb question but, did you retrieve and identify the code? did you try to clear it and it comes back? what code is it?
m

 

May I revive this thread?

Here is my issue: 2014 FXSB purchased used. It had V&H big radius pipes and they were very rusted out. (Heat shields and the inner pipes). Replaced them with V&H short shots and go figure the O2 sensor bungs are 12mm. The old big radius had 18mm bungs and the associated O2 sensors - wide band (5 wire). Didn’t think of this when I placed the order. The Harley service manual shows all possible ECM combinations for my bike’s O2 sensor are 4 wire. Previous owner must have replaced the ECM. I haven’t found any 12mm wide band sensors for my bike so I’m thinking they don’t exist. Any thoughts on a quick fix to get rid of the check engine light? So far black tape is the best option.

I don’t want to take the pipes off and replace the 12 mm bungs with 18 mm. I’m content with staring at the light

The SERT tuner is a decent option and the same price as new O2 sensors but that won’t turn off the check engine light,
correct?

I’ve researched the diode/resistor combination and have come up short so far.

The bike is stage 1 and I don’t plan on changing. I might consider another tuner but I don’t need any performance
upgrades; I just want the check engine light off.