Fuel Injection System - TBI: Description
Jeep/Renix throttle body fuel injection (TBI) system uses electronic controls to inject metered amount of fuel above throttle blade inside throttle body. Throttle body system has 2 subsystems, 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.
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, throttle position sensor (TPS), closed throttle (idle) switch, power steering pressure switch (if equipped), oxygen (O(2)) sensor, engine speed and crankshaft position sensors, shift position (A/T only), starter relay, load swap relay (A/C only), battery voltage signal, and detonation (knock) sensor.
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, ignition power module, A/C compressor clutch relay, and idle speed actuator (ISA) motor.