Introduction

Introduction

GEMS (Generic Engine Management System) is a combined electronic ignition and fuel injection system which also combines other features such as idle speed control, security functions and engine load management functions. GEMS has an internal fault monitoring system, which can be interrogated by a standard serial link.

GEMS controls the engine fuelling by providing full sequential fuel injection. Ignition is controlled by a Direct Ignition System (DIS), which is provided by 4 double-ended ignition coils operating on the wasted spark principle. A fully synchronous system is realized by the incorporation of a camshaft sensor and with the inclusion of Knock Sensors, GEMS is able to detect and correct for knock , advancing or retarding each individual cylinder independently to give optimum performance.

The GEMS Electronic Control Module (ECM) has various sensors fitted to the engine which give it information about how the engine is performing, how much air is entering, what throttle angle is requested, the current temperature of the air, fuel and coolant, the oxygen content in the exhaust, etc. The signals from these sensors are fed to the GEMS Module which processes them and decides what actions to take on the information it has received, and feeds these to its actuators (injectors, coils etc.).

GEMS software essentially can be split into two parts, the system software and the tune data.
- The system software controls the overall operational strategy of the engine management system.
- The tune data or tune is vehicle specific data such as the fuelling and ignition-mapped data, which the system software uses to control the engine management system for specific conditions.
The system software and tune data are stored in read only memory. GEMS also contains non-volatile memory in which learned values and the fault codes are stored.