Fuel Injection System. Fuel Injection System. Uses pressure (not Vacuum) from an electrical pump to spray fuel into the intake manifold. Provides the engine with proper air-fuel ratio (14.7 : 1). Fuel Injection System. Advantages. Improved Atomization . Better fuel flow .
Engine Throttle Valve
Electronic Fuel Injection uses various engine sensors and control
module to regulate the opening and closing of injector valve.
Injector Pulse Width indicates the time each
Injector is energized (Kept Open).
Oxygen Sensor measures the oxygen content in engine exhaust.
Manifold Absolute Pressure Sensor (MAP)
Throttle Position Sensor (TPS)
Engine Temperature Sensor
Mass Air Flow Sensor (MAF)
Inlet Air Temperature Sensor
Crankshaft Position Sensor
Fast Idle Thermo Valve
Idle Air Control Motor (IAC)
EFI Multi port Injection System
EFI Direct fuel Injection System
***Do not be confused with ignition or engine mechanical problems.
***Do not disconnect EFI harness terminal when ignition in
OBD (On Board Diagnostics) & OBD II
Pressure Regulator Testing
***Caution – Relieve fuel pressure (up to 60psi)before disconnecting line.
Check clogged fuel filter or bad electric pump.
Usually bad pressure regulator.
Maximum Fuel Pressure Test
Bad injector can cause
Leaky Injectors will richen the
Dirty Injectors restricts the air-
flow, causing a lean mixture.
Inoperative EFI Injectors
no action (Miss Fire)
Infinite Resistance=Open coil
Zero resistance to ground = shorted.
Injector noid light
***caution – Some manufacturers do not recommend cleaning injectors
Cold = Low resistance.
Hot = High resistance.