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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
Automotive Service
Upstream = PreCAT
Downstream = PostCAT
Automotive Service
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.
Automotive Service
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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