2. 2
Types of Fuel InjectionTypes of Fuel Injection
SystemsSystems
Port fuel injection. (PFI/MPFI)Port fuel injection. (PFI/MPFI)
Throttle Body Fuel Injection. (TBI)Throttle Body Fuel Injection. (TBI)
Mechanical or CIS injection system.Mechanical or CIS injection system.
1958 Corvette 11958 Corvette 1stst
fuel injection (Manual)fuel injection (Manual)
3. 3
Electronic Injection SystemElectronic Injection System
Electronic PartsElectronic Parts
Computer (PCM):Computer (PCM):
logic device.logic device.
Sensors :Sensors :
input data to theinput data to the
computer.computer.
Actuators :Actuators :
output devices theoutput devices the
computer operates.computer operates.
Mechanical PartsMechanical Parts
Fuel tank.Fuel tank.
Fuel pump.Fuel pump.
Fuel filter and lines.Fuel filter and lines.
Injector or injectors.Injector or injectors.
Fuel rail.Fuel rail.
Pressure regulator.Pressure regulator.
4. 4
Electronic PartsElectronic Parts
Electronic PartsElectronic Parts
Computer (PCM) -Computer (PCM) -
logic device.logic device.
SensorsSensors
input data to theinput data to the
computer.computer.
ActuatorsActuators
output devices theoutput devices the
computer operatescomputer operates
5. 5
Fuel Filter and Fuel LinesFuel Filter and Fuel Lines
Sock on gas pumpSock on gas pump
InlineInline
Screen in injectorScreen in injector
6. 6
Fuel Rail & PressureFuel Rail & Pressure
RegulatorRegulator
The rail - pipe thatThe rail - pipe that
fills the injectors.fills the injectors.
Pressure regulatorPressure regulator
controls the pressurecontrols the pressure
to injectors.to injectors.
Pressure adjustedPressure adjusted
for changes in intakefor changes in intake
manifold vacuum.manifold vacuum.
Some areSome are
mechanical butmechanical but
newer cars use annewer cars use an
7. 7
Fuel InjectorsFuel Injectors
InjectorsInjectors
electrically operated valve.electrically operated valve.
Fuel pumpFuel pump
pumps fuel to injector frompumps fuel to injector from
fuel tankfuel tank
holds pressure against eholds pressure against e
injector’s valve.injector’s valve.
Computer triggers valveComputer triggers valve
with electrical signalwith electrical signal
called a pulse.called a pulse.
(pulse width)(pulse width)
8. 8
Fuel Injector PartsFuel Injector Parts
““O” Ring sealsO” Ring seals
fuel railfuel rail
intake manifold.intake manifold.
Solenoid inside,Solenoid inside,
note electricalnote electrical
connection.connection.
Pintle NeedlePintle Needle
at spray endat spray end
where fuel shootswhere fuel shoots
out.out.
9. 9
How the Injector FiresHow the Injector Fires
The computer grounds the injector toThe computer grounds the injector to
turn itturn it “pulse” -- “Pulse width”“pulse” -- “Pulse width”
Pulses timed by crankshaft sensorPulses timed by crankshaft sensor
(CKPS). And/or camshaft sensor (CPS).(CKPS). And/or camshaft sensor (CPS).
Three ways to fire the injectors:Three ways to fire the injectors:
1. Group1. Group
2. Gang injection2. Gang injection
3. Sequential injection3. Sequential injection
11. 11
Electronic Sensors (Inputs)Electronic Sensors (Inputs)
• MAP Manifold Absolute PressureMAP Manifold Absolute Pressure
• MAF Mass Air FlowMAF Mass Air Flow
• ECT Engine Coolant TemperatureECT Engine Coolant Temperature
• IAT Intake Air TemperatureIAT Intake Air Temperature
• TPS Throttle Position SensorTPS Throttle Position Sensor
• VSS Vehicle Speed SensorVSS Vehicle Speed Sensor
• O2 Exhaust Oxygen SensorO2 Exhaust Oxygen Sensor
• CKP Crankshaft PositionCKP Crankshaft Position
• CMP Camshaft PositionCMP Camshaft Position
• KS Knock or Detonation SensorKS Knock or Detonation Sensor
12. 12
Manifold Absolute PressureManifold Absolute Pressure
Sensor (MAP)Sensor (MAP)
Measures differenceMeasures difference
between atmosphericbetween atmospheric
pressure and intakepressure and intake
manifold vacuum.manifold vacuum.
13. 13
Mass Air Flow Sensor (MAF)Mass Air Flow Sensor (MAF)
Measures mass ofMeasures mass of
air entering intakeair entering intake
manifold.manifold.
14. 14
Throttle Position Sensor (TPS)Throttle Position Sensor (TPS)
Measure throttleMeasure throttle
angle for PCM.angle for PCM.
Electronically: it’s aElectronically: it’s a
potentiometer.potentiometer.
The voltage signalThe voltage signal
changes aschanges as
resistance in pot.resistance in pot.
changes.changes.
15. 15
Engine Coolant TemperatureEngine Coolant Temperature
Sensor (ECT)Sensor (ECT)
Measure enginesMeasure engines
coolant temperature.coolant temperature.
Sensor mounted inSensor mounted in
engines waterengines water
jacket.jacket.
16. 16
Intake Air Temperature (IAT)Intake Air Temperature (IAT)
Works like CTSWorks like CTS
-measures --measures -
temperature oftemperature of
intake air.intake air.
detect intake airdetect intake air
temperaturetemperature
achieving theachieving the
precise control ofprecise control of
the A/F ratio.the A/F ratio.
18. 18
Oxygen Sensor (O2 or HO2S)Oxygen Sensor (O2 or HO2S)
Measure the amount ofMeasure the amount of
oxygen in the exhaustoxygen in the exhaust
stream.stream.
Low voltage <.45 is aLow voltage <.45 is a
lean signal.lean signal.
High voltage >.45 is aHigh voltage >.45 is a
rich signal.rich signal.
1996 /newer use two1996 /newer use two
O2 sensors.O2 sensors.
Some O2 sensors areSome O2 sensors are
heated. ( HO2S)heated. ( HO2S)
21. 21
Knock Sensor (KS)Knock Sensor (KS)
Senses detonation whichSenses detonation which
the engine is running.the engine is running.
PCM will retard sparkPCM will retard spark
when detonation iswhen detonation is
detected.detected.
22. 22
Computer Actuators (Outputs)Computer Actuators (Outputs)
Fuel InjectorsFuel Injectors
IAC Idle Air ControlIAC Idle Air Control
Fuel Pump RelayFuel Pump Relay
CANP Canister PurgeCANP Canister Purge
EGR RegulatorEGR Regulator
Cooling Fan RelayCooling Fan Relay
Torque ConverterTorque Converter
MIL-Malfunction IndicatorMIL-Malfunction Indicator
LampLamp
