The Application of a Resistive Type O2 Sensor to a Small Engine EFI System

Recent concern over air quality has lead to increasingly stringent emissions regulations on ever smaller displacement engines, resulting in the application of Electronic Fuel Injection (EFI) to the 100cc-200cc class 2-wheelers in many countries. In the pursuit of ever smaller and less expensive EFI systems a number of unique technologies are being explored, including resistive type oxygen sensors. In this paper we investigate the application of a prototype resistive oxygen sensor to a small motorcycle EFI system. Measurements of the exhaust system temperatures, and Air/Fuel Ratio (AFR) and resistive sensor response are carried out, and compared to the standard zirconia oxygen sensor to create an estimate of the sensor's in-use performance. Motorcycle performance data are compared using both a standard zirconia switching type oxygen sensor, and the new resistive type oxygen sensor to control the air/fuel ratio. Results indicate that the resistive type oxygen sensor is capable of allowing the EFI controller to successfully control the vehicle's AFR in all operating modes with a significantly faster “light off” time, and lower overall current draw when compared to the standard heated zirconia sensor.