Isuzu Motors Ltd. and Delphi Automotive Systems say their “ion sense” ignition subsystems — in use for the past year on Isuzu Troopers and Rodeos — have enabled cuts in emissions and fuel usage while adding value by integrating functions.

The ion-sense system consists of an individual ignition coil for each cylinder and a central control module, none of which have any moving parts. After the spark fires the cylinder's air/fuel mixture, the system applies a DC current to the sparkplug gap, turning the spark plug into a sensor. When there are ions present in the gap, there are changes in the DC current that can be translated into useful information about the effectiveness of the combustion process.

Delphi says the ion sense system eliminates the need for the individual crankshaft, camshaft and rough-road sensors typically used for engine-management information. Also, the in-cylinder sensing of misfire and knock is an improvement over most current methods.

Phil Peterson, Delphi's technical project manager for the ion sense system, says in a statement, “Today, Delphi's ion sense ignition subsystems provide great misfire and knock detection and the system will be the foundation for future technology enhancements. By extracting further information from the signal, other advanced functions such as air/fuel ratio detection will be possible.”

AB Saab also has for some time employed a similar system as part of its noted “Trionic” engine management system, which now is 32-bit processor-controlled and is in its seventh generation.