Air Fuel Sensor
Electric Connection
The lambda probe does not receive power from Accudyno, so it is only necessary to connect the probe signal to input AN1 (terminal 1) and common ground GND (terminal 3).
A wideband oxygen sensor can be used with its corresponding controller through the Wideband analog output.
Can I use a 5-wire sensor (Wideband)?
You can use a Wideband sensor, but you need to use a Wideband controller. It is not possible to connect a Wideband sensor directly, without a controller, to Accudyno. The Wideband controller is usually a dashboard gauge or display that has the signal conditioner inside it and allows the Wideband lambda sensor to be connected on one side, and it has auxiliary analog output cables that are the ones that are connected to Accudyno.
Universal 4-wire narrowband sensors can be connected directly, as they do not require a controller.
In the Knowledge Base you will find more information about the mounting of the sensor, and a list of the most common sensors and the colors of cables and connection of each one. This list is not exclusive and other oxygen sensors that are not listed here can be connected.
Pinout
| Number | Name | Function |
|---|---|---|
| 1 | AN1 | Signal input from the AFR Sensor or Controller |
| 3 | GND | Ground from the sensor or controller |
Applications of Lambda Measurement
The lambda value is independent of the type of fuel. The stoichiometric lambda will always be 1.0. But the AFR value, that is, the relationship between grams of air and grams of fuel will depend of the type of fuel. For example, the AFR that corresponds to a lambda 1.0 will be 14.7 for gasoline.
That means that for the combustion to be stoichiometric, it is necessary to burn 1 gram of gasoline for every 14.7 grams of air. Or what is the same, to convert from lambda to AFR you have to multiply the lambda value by 14.7 for gasoline or by 6.47 for methanol.
For your convenience, these values are preloaded into the Accudyno system.
| Fuel | Stoichiometric value |
|---|---|
| Gasoline | 14.7 |
| Diesel | 14.5 |
| Methanol | 6.47 |
| Ethanol | 9.0 |
What is the optimal value of lambda?
The optimal value will depend on what the goal is. In standard gasoline cars, it will be above 14.7 in regime, with a lean mixture of about 15.4 because it is the value with the least consumption and lower emissions. Although the value may vary depending on the driving condition, for example during acceleration the mixture will be enriched to give more power momentarily.
However, in racing sports you will want maximum power, even despite having high consumption and emissions. In that case the typical lambda value is around 0.85 to 0.88, which corresponds to 12.5 to 13.0 AFR for gasoline. The value can be higher or lower and with the help of the dyno you will be able to discover what the optimal value is for your engines.
Software Calibration
You can find the calibration method for different oxygen sensors in this link