The Renix throttle body fuel injection system is a "pulse time" system that uses a single solenoid-type injector to meter fuel into the throttle body above the throttle blade. Fuel is metered to the engine by an Electronic Control Unit (ECU), which controls the amount of fuel delivery according to input from various engine sensors that monitor exhaust gas oxygen content, coolant temperature, manifold absolute pressure, crankshaft position and throttle position. These sensors provide an electronic signal by varying resistance within the sensor itself. By reading the difference in resistance, the ECU can determine engine operating conditions and calculate the correct air/fuel mixture, and ignition timing under varying engine loads and temperatures. In addition, the ECU controls idle speed, emission control and fuel pump operation, the upshift indicator lamp and the A/C compressor clutch.
Renix TBI fuel injection has two main subsystems; a fuel subsystem and a control subsystem. The fuel subsystem consists of an electric fuel pump (mounted in the fuel tank), a fuel filter, a pressure regulator and the fuel injector. The control subsystem consists of a Manifold Air Temperature (MAT) sensor, a Coolant Temperature Sensor (CTS), a Manifold Absolute Pressure (MAP) sensor, a knock sensor, an exhaust gas oxygen (O 2 ) sensor, an Electronic Control Unit (ECU), a gear position indicator (automatic transmission only), a Throttle Position Sensor (TPS) and power steering pressure switch with a load swap relay. In addition to these sensors which send signals to the ECU, there are various devices which receive signals from the ECU to control different functions such as exhaust gas recirculation, idle speed control, air conditioner operation, etc.