Electronic Fuel Injection

Vocabulary

1. Injector (solenoid) 9.)emission standards

2. Stoichiometric14.7 to 1 3. Throttle body of injection 4. Port injection 10.)Types of sensors5. Electronic control module 6. Sensors 11.)DTC-check engine light 7. Pulse width 8. Oxygen sensor9. Fuel pump

What you want from your engine:

• Power• Fuel economy• Drivability

What the government wants:

• Low tail pipe emissions• Good fuel economy

Why do we have EFI ?

• The increasingly demanding emission and fuel economy standards of the 1970’s required a more accurate method of metering and mixing fuel than the carburetor could provide.

Air / fuel ratio

• By the mid-1970 most cars had catalytic converters to chemically clean the exhaust. The air fuel ratio must be accurately controlled on a vehicle equipped with a catalytic converter. A ratio of 14.7 to one is called a stochiometric ratio. For the best emissions this is the ideal ratio. This ratio will also not damage the CAT.

What is a Fuel Injector?

• A fuel injector is a small electric solenoid that very precisely controls fuel flow. Think of an injector like a high speed fluid valve.

Fuel flow through a injector.

Early 1980’s Fuel injection systems -

• By 1980 many manufactures had switched to electronically controlled fuel injection systems employing a centrally located injector . This system, called throttle body injection mounted one or two injectors where the carburetor once was.

Throttle Body Injector

Port Fuel Injection -1983

• Around 1983 manufactures discovered that placing the injectors close to the back of the intake valves gave a significant increase in all areas of engine performance. This allowed only air to flow through the intake manifold.

Port Fuel Injection

V-6 Fuel rail & injectors

Port Fuel Injected V-6

Injectors

Direct Fuel Injection

• Direct injection systems inject directly into the engines combustion chamber. This is a very harsh environment for the injector. Up until 2003 direct injection was only used for diesel engines. As of 2006 only Five manufactures use gas DI.

Direct Injection

D.I. System Parts

D.I. Engine

Types of EFI control systems

• Speed / density systems use a Manifold Absolute Pressure (MAP) sensor & engine RPM to calculate engine fuel needs.

• Not as accurate as Air density type system.

Types of EFI control systems

• Air Density systems use a Mass Air Flow (MAF) sensor along with many other sensors to adjust Air fuel ratio.

• Very accurate.

Review : The Three Injector placements Are:

Review:

• 1. why do we have EFI?• 2. What is an Injector?• 3. What is the name for the on • - off cycling of a injector?• 4. Name three types of Injector• placement.• 5. Name the two types of EFI • management systems.

PART 2

EFI

• Please check you grade on line ASAP .

• Make up missing work or low test scores !

Basic EFI system

•Sensor inputs•PCM (computer)•Outputs

EFI System Organization

2007 EFI organization :

EFI System Inputs:

• Sensors are used to give the Computer (ECM) information to make decisions (Outputs)

Critical Inputs (sensors)

Crankshaft position sensor location & types:

Inputs (Sensors)

Inputs (sensors)

Inputs (Sensor)

The ECM or PCM

• The PCM is the device that receives information. It then makes control decisions that affect output devices like injector pulse width and transmission shift points.

ECM or PCM

Programmable read only memory • The Programmable read only memory

or (prom) is placed on a chip that is inserted into the ECM. It contains the basic Parameters that a specific engine / vehicle will be operated under. Engine size, Gear ratio, vehicle weight , vehicle options, the environment the vehicle will be sold in are all contained on the PROM chip .

A PROM chip

chip

When a EFI system uses all it’s sensors to help make decisions its called closed loop operation. Closed loop is the most accurate mode the EFI system can operate under. When a car is first started (cold) the system run’s on the prom info. This is because the O2 sensor is not functioning when cold. This mode of operation is called open loop.

Typical EFI Outputs

• Ignition system• Idle air control valve (idle speed)• MIL light or SES light• Transmission• Fuel pump relay• Fuel injectors• Cooling fans• Emission control systems

Typical EFI Outputs

EFI Fuel supply parts

Fuel pressure Regulator

EFI Ignition systems

• PCM depends on crank shaft position sensor, cam sensor (the primary sensors) to control spark timing. Other sensors are also used.

• Distributor , DIS and Coil on plug ignition systems are all computer controlled and considered part of the engine management system.

DIS Ignition system

Diagnostics:How do you fix EFI?

• 1. check SES/MIL light.• 2. use scan tool or code reader.• 3. Check for DTC’s• 4. Identify DTC’s• 5. Check data stream for out of

parameter sensors & outputs.• 6. Get diagnostic charts for DTC’s found.• 7. know how to use test equip to follow

diagnostic charts.

EFI SCAN TOOL

Typical DTC Chart :

Summery :

• EFI systems have : Inputs, the PCM & outputs.

• When the pcm uses all sensors it is in closed loop.

• The best Air/fuel ratio for emissions is 14.7 to 1

• Your MIL tells you when the computer has detected a problem.

• Scan tools can get DTC’s and data.

Hope you took notes! Good luck on test!

Electronic Fuel Injection