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Permission granted to reproduce for educational use only. 1 © Goodheart-Willcox Co., Inc.

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Presentation on theme: "Permission granted to reproduce for educational use only. 1 © Goodheart-Willcox Co., Inc."— Presentation transcript:

1 Permission granted to reproduce for educational use only. 1 © Goodheart-Willcox Co., Inc.

2 Permission granted to reproduce for educational use only. 2 © Goodheart-Willcox Co., Inc. Chapter 28 Fuel and Emission Control Systems Electronics Service

3 Permission granted to reproduce for educational use only. 3 © Goodheart-Willcox Co., Inc. Objectives Recall the tasks involved in a preliminary inspection of the injection system. Test electrical/electronic components found on late-model fuel and emission control systems. Use a fuel system wiring diagram to locate all the components in the circuit that could be causing problems.

4 Permission granted to reproduce for educational use only. 4 © Goodheart-Willcox Co., Inc. Objectives Summarize OBD II monitoring features used on late-model fuel injection and emission control systems.

5 Permission granted to reproduce for educational use only. 5 © Goodheart-Willcox Co., Inc. Fuel Injection Electronics Service Fuel injection is controlled electronically Electric fuel pumps Sensors Electronic control units Fuel metering keeps each cylinder at maximum efficiency

6 Permission granted to reproduce for educational use only. 6 © Goodheart-Willcox Co., Inc. Injection System Inspection Check condition of all system components Look and smell for fuel leaks Listen for vacuum leaks Check terminals of wiring harness

7 Permission granted to reproduce for educational use only. 7 © Goodheart-Willcox Co., Inc. Fuel System On-Board Diagnostics Self-diagnostic mode Trouble codes in older systems Compare to charts in service manual Scan tool

8 Permission granted to reproduce for educational use only. 8 © Goodheart-Willcox Co., Inc. OBD II Fuel System MonitoringFuel System Monitoring Feedback from primary oxygen sensor controls fuel mixture Adjustments Short term fuel trim Long term fuel trim

9 Permission granted to reproduce for educational use only. 9 © Goodheart-Willcox Co., Inc. Injector Noid Light TestNoid Light Disconnect wiring harness Fit noid light into harness connector Start engine and check light Repeat on all nonworking injectors (OTC/SPX Corp.)

10 Permission granted to reproduce for educational use only. 10 © Goodheart-Willcox Co., Inc. Injector Balance Test Connect pressure gauge to test fitting Close fuel volume measurement valve Connect balance tester to injector Turn ignition key on to pressurize system Turn ignition key off Press tester button

11 Permission granted to reproduce for educational use only. 11 © Goodheart-Willcox Co., Inc. Injector Balance Test (Cont.) Watch pressure gauge drop Record pressure drop reading Repeat for other injectors Compare injector readings

12 Permission granted to reproduce for educational use only. 12 © Goodheart-Willcox Co., Inc. Injector Balance Test (Cont.) (Chevrolet)

13 Permission granted to reproduce for educational use only. 13 © Goodheart-Willcox Co., Inc. Fuel System Wiring Diagrams Show all components in circuit Consult if you have difficulty finding problem

14 Permission granted to reproduce for educational use only. 14 © Goodheart-Willcox Co., Inc. Review In general, how can you tell if a vacuum hose has a leak? Answer: Listen for the characteristic “hiss.”

15 Permission granted to reproduce for educational use only. 15 © Goodheart-Willcox Co., Inc. Review The temporary adjustment of injector pulse width to correct the fuel mixture is referred to as short term _____. Answer: fuel trim

16 Permission granted to reproduce for educational use only. 16 © Goodheart-Willcox Co., Inc. Injector Problems Bad injector Shorted or open coil windings Injector or engine misfire trouble code Leaking injector Worn or dirty injector Weak or broken return spring

17 Permission granted to reproduce for educational use only. 17 © Goodheart-Willcox Co., Inc. Injector Problems (Cont.) Dirty injector Lean air-fuel ratio Poor spray pattern Inadequate fuel delivery

18 Permission granted to reproduce for educational use only. 18 © Goodheart-Willcox Co., Inc. Servicing EFI Injectors Check with stethoscope Check coil condition (engine off) Measure resistance across injector coil Check wiring to injector Check supply voltage to injector

19 Permission granted to reproduce for educational use only. 19 © Goodheart-Willcox Co., Inc. Replacing Multi-Point Injectors Bleed off fuel system pressure Remove hose from injector and fuel rail Unplug electrical connection Remove injector Inspect rubber parts Replace injector and rubber parts, if necessary

20 Permission granted to reproduce for educational use only. 20 © Goodheart-Willcox Co., Inc. Replacing Multi-Point Injectors (Cont.) (Ford)

21 Permission granted to reproduce for educational use only. 21 © Goodheart-Willcox Co., Inc. Fuel Tank Sending Unit Service Test fuel gauge before sending unit Use ohmmeter to test sending unit For further testing, remove sending unit Measure resistance Check float for leakage

22 Permission granted to reproduce for educational use only. 22 © Goodheart-Willcox Co., Inc. Fuel Tank Sending Unit Service (Cont.) (Honda Motor Co.)

23 Permission granted to reproduce for educational use only. 23 © Goodheart-Willcox Co., Inc. Fuel Pump Service Low fuel pump pressure Worn pump bearings High resistance in pump circuit Leaking check valves High fuel pump pressure Inoperative pressure relief valve Faulty fuel pressure regulator

24 Permission granted to reproduce for educational use only. 24 © Goodheart-Willcox Co., Inc. Electric Fuel Pump Circuit Tests Perform pressure and volume tests Measure voltage to pump motor (Honda Motor Co.)

25 Permission granted to reproduce for educational use only. 25 © Goodheart-Willcox Co., Inc. Fuel Pressure Sensor Monitors fuel pressure Measures fuel temperature Read trouble code on scan tool

26 Permission granted to reproduce for educational use only. 26 © Goodheart-Willcox Co., Inc. Fuel Pump Shutoff Circuits Inertia switch Blocks fuel flow after impact Oil pressure switch Shuts off fuel pump if oil pressure is low

27 Permission granted to reproduce for educational use only. 27 © Goodheart-Willcox Co., Inc. Review While using a stethoscope to check an EFI injector, you hear a clicking sound. What does this mean? Answer: The injector is working (opening and closing).

28 Permission granted to reproduce for educational use only. 28 © Goodheart-Willcox Co., Inc. Review What type of switch is used to block current flow to the electric fuel pump after a collision? Answer: inertia switch

29 Permission granted to reproduce for educational use only. 29 © Goodheart-Willcox Co., Inc. Emission Control System Electronics Service Defects in computer-controlled parts EGR valve Evaporative emission purge valve Air injection Other components OBD II

30 Permission granted to reproduce for educational use only. 30 © Goodheart-Willcox Co., Inc. Emission Maintenance Reminder Dash light reminder for emission control service Must be deactivated after adjustments and repairs are done Numerous methods Refer to service manual

31 Permission granted to reproduce for educational use only. 31 © Goodheart-Willcox Co., Inc. OBD II Monitoring Evaporative emissions system EGR Air injection system Oxygen sensor Catalyst monitor

32 Permission granted to reproduce for educational use only. 32 © Goodheart-Willcox Co., Inc. Emission System Scanning Scan tool monitoring of various emission control systems Connect scan tool Check for stored trouble codes Think about what could cause codes

33 Permission granted to reproduce for educational use only. 33 © Goodheart-Willcox Co., Inc. Inspecting Emission Control Systems Inspect engine vacuum hoses and wires Listening devices Piece of vacuum hose Stethoscope without metal probe (Snap-on Tool Corp.)

34 Permission granted to reproduce for educational use only. 34 © Goodheart-Willcox Co., Inc. Inspecting Emission Control Systems (Cont.) Look for oil leaks onto oxygen sensor Check for dirty engine oil and blowby Inspect air cleaner Check adjustment of air pump belt

35 Permission granted to reproduce for educational use only. 35 © Goodheart-Willcox Co., Inc. Vacuum Solenoid Service Refer to vacuum hose diagram Check for Hard, brittle hoses Voltage to vacuum Check solenoid valve operation

36 Permission granted to reproduce for educational use only. 36 © Goodheart-Willcox Co., Inc. Evaporative Emissions Control System Service Evaporative emissions system purge test Evaporative emissions system pressure test Evaporative emissions control system maintenance Replace filter Inspect fuel tank filler cap and hoses

37 Permission granted to reproduce for educational use only. 37 © Goodheart-Willcox Co., Inc. Evaporative Emissions Control System Service (Cont.) (Honda Motor Co.)

38 Permission granted to reproduce for educational use only. 38 © Goodheart-Willcox Co., Inc. Review Another name for the secondary oxygen sensor is _____. A. elemental sensor B. catalyst monitor C. front sensor D. primary sensor Answer: B. catalyst monitor

39 Permission granted to reproduce for educational use only. 39 © Goodheart-Willcox Co., Inc. Review Which test measures the flow of fuel vapors into the engine? Answer: evaporative emissions system purge test

40 Permission granted to reproduce for educational use only. 40 © Goodheart-Willcox Co., Inc. EGR System Electronic Service EGR valve sticks open Engine stalling at idle Rough idle EGR valve fails to open Detonation Knocking

41 Permission granted to reproduce for educational use only. 41 © Goodheart-Willcox Co., Inc. Electronic EGR System Testing EGR valves trip trouble code Use scan tool or refer to shop manual Use oscilloscope to pinpoint trouble

42 Permission granted to reproduce for educational use only. 42 © Goodheart-Willcox Co., Inc. Electronic EGR System Testing (Cont.) (Fluke)

43 Permission granted to reproduce for educational use only. 43 © Goodheart-Willcox Co., Inc. Electric PCV Valve Service New versions are electric Older valves are spring loaded Use scan tool to locate problems

44 Permission granted to reproduce for educational use only. 44 © Goodheart-Willcox Co., Inc. Testing the MAP Sensor (Fluke)

45 Permission granted to reproduce for educational use only. 45 © Goodheart-Willcox Co., Inc. Testing the MAP Sensor (Cont.) Digital MAP Signal (Fluke)

46 Permission granted to reproduce for educational use only. 46 © Goodheart-Willcox Co., Inc. Testing the MAP Sensor (Cont.) Analog MAP Signal (Fluke)

47 Permission granted to reproduce for educational use only. 47 © Goodheart-Willcox Co., Inc. Oxygen Sensor Service Check during engine rev and deceleration Lazy O 2 sensor Dead O 2 sensor Replace sensor at periodic intervals

48 Permission granted to reproduce for educational use only. 48 © Goodheart-Willcox Co., Inc. Testing Oxygen Sensors (Fluke)

49 Permission granted to reproduce for educational use only. 49 © Goodheart-Willcox Co., Inc. Testing Wide Band Oxygen Sensors Also called air-fuel ratio sensor 3.3 volts is normal Other voltages result in trouble code Scan tool Oxygen sensor signal generator

50 Permission granted to reproduce for educational use only. 50 © Goodheart-Willcox Co., Inc. Emissions Testing Emissions testing program Inspection and maintenance programs Exact procedures vary from state to state

51 Permission granted to reproduce for educational use only. 51 © Goodheart-Willcox Co., Inc. Review What symptoms might indicate that an EGR valve is stuck shut? Answer: detonating or knocking

52 Permission granted to reproduce for educational use only. 52 © Goodheart-Willcox Co., Inc. Review A(n) _____ oxygen sensor is one that does not alter its output signal fast enough to maintain an efficient air-fuel ratio. Answer: lazy

53 Permission granted to reproduce for educational use only. 53 © Goodheart-Willcox Co., Inc. Glossary Catalyst monitor An oxygen sensor that is located after the catalytic converter. It checks the oxygen content of the exhaust gases after exiting the catalytic converter to determine if the catalyst elements are working. Also called secondary oxygen sensor or rear oxygen sensor.

54 Permission granted to reproduce for educational use only. 54 © Goodheart-Willcox Co., Inc. Glossary Emission maintenance reminder A circuit that automatically turns on a dash light to indicate the need for emission control system service. Some vehicles use a mechanical flag that is located inside the speedometer cluster. Emission system scanning Involves using a scan tool to check the condition of monitored parts of the various emission control systems.

55 Permission granted to reproduce for educational use only. 55 © Goodheart-Willcox Co., Inc. Glossary Emissions testing program A program that involves taking exhaust gas readings as a vehicle’s engine operates at idle and at a set rpm. It may also involve checking the vehicle for the presence of a catalytic converter and a fuel inlet restrictor. Also called an inspection and maintenance program.

56 Permission granted to reproduce for educational use only. 56 © Goodheart-Willcox Co., Inc. Glossary Evaporative emissions system pressure test A test that checks the emission system for leaks into the atmosphere. The pressure test equipment is connected to the evaporative emission system’s vapor vent line. A computer then meters low pressure nitrogen into the system (evaporative emission system, fuel lines, fuel tank, and filler neck).

57 Permission granted to reproduce for educational use only. 57 © Goodheart-Willcox Co., Inc. Glossary Evaporative emissions system purge test A test that measures the flow of fuel vapors into the engine. Fuel system monitoring Involves checking whether a stoichiometric, or theoretically perfect, fuel mixture is being fed to the engine.

58 Permission granted to reproduce for educational use only. 58 © Goodheart-Willcox Co., Inc. Glossary Injector balance test A common test performed on modern multi- point or direct electronic fuel injection systems. It involves the use of a fuel injector tester, or EFI analyzer, to measure the amount of fuel flowing through each injector. It will tell you if any injectors are clogged, cracked, shorted, or not opening fully.

59 Permission granted to reproduce for educational use only. 59 © Goodheart-Willcox Co., Inc. Glossary Inspection and maintenance program A program that involves taking exhaust gas readings as a vehicle’s engine operates at idle and at a set rpm. It may also involve checking the vehicle for the presence of a catalytic converter and a fuel inlet restrictor. Also called an emissions testing program.

60 Permission granted to reproduce for educational use only. 60 © Goodheart-Willcox Co., Inc. Glossary Long term fuel trim A permanent adjustment of injector pulse width to compensate for altered operating parameters. Noid light A test light that is used to check electronic fuel injector feed circuits. Oxygen sensor signal generator A tool used to send a false 200 mV to 700 mV signal to the computer for testing purposes.

61 Permission granted to reproduce for educational use only. 61 © Goodheart-Willcox Co., Inc. Glossary Short term fuel trim Refers to the temporary adjustment of injector pulse width to correct the fuel mixture.


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