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Automotive Service Modern Auto Tech Study Guide Chapters 22 & 23 Pages 340 ­ 395 Electronic Fuel Injection 45 Points

Automotive Service 1. Gasoline _________________ systems spray pressurized fuel into

the engine’s intake manifold ports.

Protection Rejection Injection

Automotive Service 2. As compared to __________________ ­ type fuel systems, injection offers

improved atomization, better fuel distribution, smoother idle, improved fuel economy, lower emissions, increased engine power, better cold­weather driveability & even though it is computer controlled, it is a simpler system!

Carburetor SFI MPFI

Automotive Service 3. _________________ differences between two areas can cause flow.

In an engine air & fuel will flow from atmospheric pressure (high) toward engine vacuum (low) pressure. The throttle controls this flow.

Voltage Pressure Heat

Automotive Service 4. _______________ _______ injection (TBI) systems spray fuel into the intake

manifold at a central point.

Unibody Hard Body Throttle Body

Automotive Service 5. _______________ injection systems spray fuel into each intake port

of the engine near the intake valves.

Multiport Direct Continuous

Automotive Service 6. INDIRECT injection delivers fuel into the manifold.

DIRECT injection sprays fuel into the cylinder.

Automotive Service 6. INDIRECT injection delivers fuel into the manifold.

DIRECT injection sprays fuel into the cylinder.

http://www.youtube.com/watch?v=73BrXCsbd64

Automotive Service 7. Of electronic, hydraulic, & mechanical gasoline injection controls,

________________ is most common.

Automotive Service

Automotive Service 8. _________________ (SFI) fuel injection pulses the injectors according to the

firing order of the engine.

Sequential Direct Continuous

Automotive Service 9. The fuel delivery subsystem of EFI uses a fuel pressure ______________ to

control injector pressure. (often vacuum or load sensitive)

Regulator Alternator Pump & PCM (ask me…)

Automotive Service 10. An _____________ for an EFI system

is a coil or solenoid­operated fuel valve that is closed when off.

Detector Reactor Injector

Automotive Service 11. The air induction sub system filters, controls, distributes, and monitors

the amount of ______ flowing in.

Air Fuel Exhaust

Electronic Engine Control System Block Diagram

HO2S

TPS

ECT

IAT

MAF

MAP

CKP

CMP

P/N

KS

VSS

PCM

ABS

Chassis

SRS HVAC Anti­Theft

Body

DLC

MIL

Electronic Engine Control System Block Diagram

Ignition Spark

EFI

Emission Controls

Cruise

Accessories

Engine Outputs

Inputs

Open Loop Mode Closed Loop Mode Clear Flood Mode

Scan Tool

Sensors

Actuators

Limp­In Mode

HO2S

TPS

ECT

IAT

MAF

MAP

CKP

CMP

P/N

KS

VSS

PCM PROM & RAM

ABS

Chassis

SRS HVAC Anti­Theft

Body

DLC

MIL

Electronic Engine Control System Block Diagram

Ignition Spark

EFI (injectors & IAC)

Emission Controls (6) CAT – AIR – PCV TAC – EVAP – EGR

Cruise

Accessories Instrument Cluster

Engine Outputs

Inputs

Open Loop Mode Closed Loop Mode Clear Flood Mode

Scan Tool

Sensors

Actuators

Limp­In Mode

Upstream (A/F) &

Downstream (CAT)

DTC’s

Automotive Service 12. The SENSOR subsystem monitors engine operating conditions and

reports data to the PCM.

Automotive Service 13. The ELECTRONIC engine control system uses a microprocessor called the

PCM (powertrain control module) to input the data from sensors and then output commands to the injectors and other actuators on the engine.

Automotive Service 14. The exhaust gas ____________ sensor (EGOS) provides a means of checking

combustion efficiency by monitoring the oxygen content in the exhaust stream both before & after the catalytic converter…(known as “feedback”)

Oxygen Olive Ominous

Bank 1 – Stream 1 Bank 1 – Upstream O2 Sensor

Automotive Service 15. During ______ loop (cold) operation the PCM ignores EGOS signals &

operates EFI with pre­set values.

Open Loop Cold Coolant (<140°) Running Less Than 2 Minutes Inactive Upstream HO2S

Automotive Service 16. During ___________ loop (warm) operation the PCM uses EGOS input to

constantly adjust the a/f mix.

Closed Loop Warm to Hot Coolant (>140°) Running More Than 2 Minutes Active & Responsive Upstream HO2S

Automotive Service 17­21. In addition to the HO2S, (EGOS) or (HEGOS) other critical sensors in the

EEC and EFI systems are:

MAP ____________ ______________ __________ sensor TPS ____________ ____________ ______ ECT ___________________ ___________ ________________ sensor MAF _____________ ________________ sensor IAT _________ ___________ ________________ sensor

A/F Wide Range Air/Fuel Sensor = Resistant Titanium O2 BPP/BOO Brake Pedal Position or Brake On­Off BARO Barometric Pressure ECT Engine Coolant Temperature CKP Crankshaft Position CMP Camshaft Position EVP EGR Valve Position IAT Intake Air Temperature KS Knock Sensor MAP Manifold Absolute Pressure (Vacuum for Load Indicator) MAF Mass Air Flow NDS Neutral­Drive Switch (Also Park/Neutral Switch or PRNDL) HO2S Heated Oxygen Sensor PS Power Steering Pressure Switch TPS Throttle Position Sensor VSS Vehicle Speed Sensor

Automotive Service

Automotive Service 22. The PCM reads data from _______________ position (CKP) &

___________ position (CMP) sensors too.

Crankshaft Position, Camshaft Position

Automotive Service 23. Some sensor signals are DIGITAL (on­off)

while some are ANALOG (changing in strength).

Analog

Digital

Automotive Service 24. The PCM controls injector ___________ ___________; the amount of time

(mSec) each injector is open.

Pulse Width Tour of Duty Burst Width

Automotive Service 24. The PCM controls injector ___________ ___________; the amount of time

(mSec) each injector is open.

Pulse Width Tour of Duty Burst Width

Automotive Service 25. To control the idle rpm of an engine, an _____ ____ ________ motor (IAC)

sets the amount of air bypassing the throttle plates when they are closed. Air leaks can upset the idle speed of an engine.

Idle Air Control Idle Activity Control Idle Action Conductivity

Automotive Service 26. ___________ multiport injection mounts all of the injectors in a single assembly

and uses plastic transfer lines and poppet nozzles to deliver the fuel

Western Central or Unitized Eastern

Central, Sequential Fuel Injection Used in GM Vortec® engines

Automotive Service 27. A ________ _________ injector is an additional fuel injector used to

supply extra fuel for cold starting.

Cold Start Continuous Shot Burst­o­Fuel

Automotive Service 28. __________ gasoline injectors of a crystalline ceramic material

are used in gasoline direct fuel injection systems. (GDI) Piezo Mechanical Chemical

Automotive Service ~~~

29. Service of all vehicle systems should start by _____________ the problem or customer complaint.

Verifying Customer Complaint

Testing to determine Cause of Problem

Making the Correction

3 C’s of auto repair

Automotive Service 30. Most EFI systems have ____ __________ _____________ (OBD) abilities.

This means that the PCM can detect and record possible system faults. DTC’s or fault codes can be read with a scan tool & interpreted by a tech.

Off Base Dimensions On Board Diagnostic On Board Dementia

Automotive Service 31. If an EEC system fault is detected, the PCM sets & stores a

________________ code (DTC) in the RAM. (temporary memory)

Fault or Trouble Diagnostic Domination

Automotive Service 32. The _________________ ________________ ___________ (MIL) on

the instrument panel glows to notify the driver or technician that there is a DTC stored. A blinking MIL really means trouble!

Malfunction Indicator Light My Idiot Light Malfunctioning Is Lousy

Automotive Service 33. A ________ tool is connected to the PCM diagnostic link (DLC) to

access stored DTC’s for diagnosis.

Diagnostic Scan Big Bucks

Automotive Service 34. Fuel ________ refers to adjustment of injector pulse width to correct the

air/fuel mixture. (STFT & LTFT)

Trim Volume Pressure

Automotive Service 35. Proper operation of the upstream ____________ sensors & their heater

circuits is necessary for efficient operation (control of A:F ratio).

Automotive Service

Automotive Service Air:Fuel Ratio Adjustment is based on Upstream Oxygen Sensor Readings

Fuel Injector

PCM

MAF

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Upstream = Pre­CAT

Downstream = Post­CAT

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Automotive Service 36. Injectors can fail by LEAKING, being clogged/dirty, or by being

totally inoperative (open circuit electrically).

Automotive Service 37. Stethoscopes & ______ Lights are used to make checks of the

electronic fuel injector feed or pulse circuit.

Noid Trouble Timing

Automotive Service 38. Fuel injectors can be _______________ if they are dirty, but replacement is

often the best option.

Cleaned Steamed Reamed

Automotive Service Explain what a “Flooded Engine” is:

A flooded engine has so much fuel in the intake manifold and cylinders that it is “puddling” in the manifold and has “wet­fouled” the spark plugs.

Automotive Service Explain “Clear Flood Mode”:

Clear Flood Mode is a way of stopping fuel flow from the injectors and Also bringing in more air into the engine to dilute the flooded condition.

Automotive Service Explain how the driver enables “Clear Flood Mode” in an EFI vehicle:

In an EFI engine: WOT & Crank the engine to “unflood it… …then give it a second or two and start as usual

Automotive Service Explain how to enable “Clear Flood” on a carbureted vehicle:

In a carbureted engine: WOT and crank it until the engine starts!

Automotive Service Explain why “Clear Flood Mode” works:

Clear Flood signals the PCM with a WOT indication under 400 RPM. The resulting output from the PCM is to decrease injector pulse width to zero.

The new common rail injection system, run by one of the most advanced control units on the market, features ultramodern piezo injectors. Its eight­hole injectors can achieve up to five separate injection processes per combustion cycle. This fine­ tuned approach produces a gentle pressure increase in the combustion chambers, decisively reducing the noise level. The single­piston high­pressure pump develops a system pressure of 1,800 bar. This allows fuel to form a fine dispersion, enabling precise, highly efficient combustion.

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Automotive Service Explain why “Clear Flood Mode” works:

In a carbureted engine, Clear Flood is also known as “Choke Unloader”… it decreases the venturi vacuum so fuel flow is diminished and also brings in more air so the flooded condition is diluted.

Automotive Service Explain “Adaptive Strategy or Limp­in Mode”

When critical sensor input is lost, is unreliable, or irrational, the PCM will substitute values for sensors to keep the engine running pretty well.

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