Fuel Injection System - High Pressure CFI: Description
High Pressure Central Fuel Injection (CFI) system is a single point, pulse time modulated system. Fuel is metered into air intake stream according to engine demands by 2 solenoid activated injection valves, mounted in the throttle body assembly on intake manifold.
CFI system has several subsystems: fuel delivery, air induction, engine condition input sensors and Electronic Control Assembly (ECA) of EEC-IV system, which provides output control signals.
Fuel is delivered by a high pressure electric fuel pump mounted in the fuel tank. Fuel is filtered and sent to the throttle body where the regulator maintains fuel pressure at a constant 39 psi (2.7 kg/cm2 ). The 2 injectors are mounted above the throttle plates and are connected in parallel with the pressure regulator. Excess fuel is returned to the fuel tank by a separate return line.
Engine input sensors used are: Throttle Position Sensor (TPS), Manifold Absolute Pressure (MAP) sensor, Engine Coolant Temperature (ECT) sensor, Air Charge Temperature (ACT) sensor, EGR Valve Position (EVP) sensor, Exhaust Gas Oxygen (EGO) sensor and Profile Ignition Pick-Up (PIP).
Output devices controlled by ECA include fuel injectors and ISC DC motor. Output signals from ECA determine fuel injection volume and engine speed.