Fuel injection: General: Notes

Fig 1: Identifying Fuel Injection - Communication Diagram

Courtesy of SAAB-SCANIA OF AMERICA, INC.

Fuel injection is sequential. Continual lambda control is done with the help of a wideband oxygen sensor. In order to maintain the correct amount of fuel, ECM varies injection timing and fuel pressure. The most important starting values for fuel injection are:

Engine speed
Air mass

Through use of a wideband oxygen sensor, lambda control can be active even if the current lambda value deviates from 1.00. This is not possible with a conventional narrow band oxygen sensor.

Some advantages of continual lambda control with wideband sensor are:

Control of he current lambda value over the entire load/engine speed range. This provides improved emissions at full load.
Possibility to have the EVAP canister purge valve active throughout the entire load/engine speed range.
Improved ability to diagnose components such as the catalytic converter and AIR.