TBI System: Description
AMC/Renix throttle body fuel injection system (TBI) uses electronic controls to inject metered amount of fuel above throttle blade inside throttle body. Throttle body system has 2 subsystems, which are fuel delivery and electronic control systems. Fuel delivery system includes in-tank fuel pump, fuel filter, fuel injector and fuel pressure regulator. Electronic control system consists of electronic control unit (ECU), input sensors and engine controls which receive output commands.
An injector, located within the throttle body, is controlled by the Electronic Control Unit (ECU). The ECU processes information from several sensors to determine engine operating conditions. It then provides output control signals to regulate air/fuel ratio, ignition, idle speed and emission control devices. This permits optimum engine performance with minimum emissions.
Sensor inputs give ECU continuous information on operating conditions of engine. Input components of control system include A/C select and temperature control switches, manifold air/fuel temperature (MAT) sensor, coolant temperature (CTS) sensor, manifold absolute pressure (MAP) sensor, wide open throttle (WOT) switch, closed throttle (idle) switch, oxygen sensor, engine speed and crankshaft position sensors, shift position (A/T), starter relay, battery voltage signal, manifold temperature (MT) sensor (1.4L only) and detonation (knock) sensor (1.7L and 2.0L only).
Based on input information, ECU sends output signals which change air/fuel mixture ratio and ignition timing as necessary to optimize performance of engine. ECU provides control for fuel delivery, idle speed and emissions through its output signals. ECU uses output signals to control system power relay, fuel pump relay, fuel injector, EGR valve and canister purge solenoid, upshift indicator (M/T), ignition power module, A/C compressor clutch relay, cold start relay (1.7L and 2.0L only) and idle speed actuator (ISA) motor.