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FUEL INJECTION SYSTEMSFUEL INJECTION SYSTEMS

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Types of Fuel Injection Types 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)

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Electronic Injection Electronic Injection System System Electronic PartsElectronic Parts Computer (PCM):Computer (PCM):

logic device.logic device. Sensors :Sensors :

input data to the input data to the computer.computer.

Actuators : Actuators : output devices the output 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.

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Electronic PartsElectronic Parts Electronic Parts Electronic Parts

Computer (PCM) - Computer (PCM) - logic device.logic device.

Sensors Sensors input data to the input data to the

computer.computer. Actuators Actuators

output devices the output devices the computer operatescomputer operates

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Fuel Filter and Fuel LinesFuel Filter and Fuel Lines

Sock on gas pumpSock on gas pump InlineInline Screen in injectorScreen in injector

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Fuel Rail & Pressure Fuel Rail & Pressure RegulatorRegulator

The rail - pipe that The rail - pipe that fills the injectors.fills the injectors.

Pressure regulator Pressure regulator controls the pressure controls the pressure to injectors.to injectors.

Pressure adjusted for Pressure adjusted for changes in intake changes in intake manifold vacuum.manifold vacuum.

Some are Some are mechanical but mechanical but newer cars use an newer cars use an electronic system.electronic system.

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Fuel InjectorsFuel Injectors Injectors Injectors

electrically operated electrically operated valve.valve.

Fuel pump Fuel pump pumps fuel to injector pumps fuel to injector

from fuel tank from fuel tank holds pressure against e holds pressure against e

injector’s valve.injector’s valve. Computer triggers Computer triggers

valve with electrical valve with electrical signal called a pulse. signal called a pulse. (pulse width)(pulse width)

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Fuel Injector PartsFuel Injector Parts ““O” Ring seals O” Ring seals

fuel rail fuel rail intake manifold.intake manifold.

Solenoid inside, Solenoid inside, note electrical note electrical

connection.connection. Pintle NeedlePintle Needle

at spray end at spray end where fuel shoots where fuel shoots

out.out.

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How the Injector FiresHow the Injector Fires

The computer grounds the injector to The computer grounds the injector to turn it turn it “pulse” -- “Pulse width”“pulse” -- “Pulse width”

Pulses timed by crankshaft sensor Pulses timed by crankshaft sensor (CKPS). And/or camshaft sensor (CKPS). And/or camshaft sensor (CPS).(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

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SensorsSensors

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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 Position CKP Crankshaft Position • CMP Camshaft PositionCMP Camshaft Position• KS Knock or Detonation SensorKS Knock or Detonation Sensor

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Manifold Absolute Manifold Absolute Pressure Sensor (MAP)Pressure Sensor (MAP)

Measures difference Measures difference between atmospheric between atmospheric pressure and intake pressure and intake manifold vacuum.manifold vacuum.

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Mass Air Flow Sensor Mass Air Flow Sensor (MAF)(MAF)

Measures mass of Measures mass of air entering air entering intake manifold.intake manifold.

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Throttle Position Sensor Throttle Position Sensor (TPS)(TPS)

Measure throttle Measure throttle angle for PCM.angle for PCM.

Electronically: it’s Electronically: it’s a potentiometer.a potentiometer.

The voltage signal The voltage signal changes as changes as resistance in pot. resistance in pot. changes.changes.

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Engine Coolant Engine Coolant Temperature Sensor (ECT)Temperature Sensor (ECT)

Measure engines Measure engines coolant coolant temperature.temperature.

Sensor mounted Sensor mounted in engines water in engines water jacket.jacket.

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Intake Air Temperature Intake Air Temperature (IAT)(IAT)

Works like CTS -Works like CTS -measures - measures - temperature of temperature of intake air.intake air.

detect intake air detect intake air temperature temperature

achieving the achieving the precise control of precise control of the A/F ratio.the A/F ratio.

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Vehicle Speed Sensor Vehicle Speed Sensor (VSS)(VSS)

Monitors VEHICLE Monitors VEHICLE SPEEDSPEED

NOT ENGINE NOT ENGINE SPEEDSPEED

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Oxygen Sensor (O2 or Oxygen Sensor (O2 or HO2S)HO2S) Measure the amount Measure the amount

of oxygen in the of oxygen in the exhaust stream.exhaust stream.

Low voltage <.45 is Low voltage <.45 is a lean signal.a lean signal.

High voltage >.45 is High voltage >.45 is a rich signal.a rich signal.

1996 /newer use two 1996 /newer use two O2 sensors.O2 sensors.

Some O2 sensors Some O2 sensors are heated. ( HO2S)are heated. ( HO2S)

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Crankshaft Position Sensor Crankshaft Position Sensor (CKP)(CKP)

Uses Notches in Uses Notches in crankshaftcrankshaft

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Camshaft Position Sensor Camshaft Position Sensor (CMP)(CMP)

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Knock Sensor (KS)Knock Sensor (KS)

Senses detonation Senses detonation which the engine is which the engine is running.running.

PCM will retard spark PCM will retard spark when detonation is when detonation is detected.detected.

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Computer Actuators Computer Actuators (Outputs)(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 Indicator MIL-Malfunction Indicator

LampLamp