© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 34 Emission Control Diagnosis and Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The quality of an engine’s exhaust depends on: – The effectiveness of the emission controls – The efficiency of the engine The three emissions controlled are: – HC, CO, and NOx Emission Control Diagnosis and Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. OBD II Test Many states use the OBD II monitors as part of a mandatory emissions inspection – Check MIL operation – Check for DTCs – Check monitor status

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. I/M Monitor Status

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. I/M 240 Test Checks emission levels during vehicle operation Simulates a short city drive and a longer highway drive The results of two phases are combined If the vehicle fails the test, it must be repaired

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. IM240 Drive Trace

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Idle, no load at 0 mph Acceleration from 0 to 35 mph Acceleration from 35 to 55 mph Steady 35 mph cruise Steady 55 mph cruise Deceleration from 35 to 0 mph Deceleration from 55 to 0 mph IM240 Drive Cycle Modes

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chassis Dynamometer Simulates various road conditions Can measure torque and speed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Other I/M Testing Programs Some states test emissions at idle only Other states precondition the vehicle by running at a high idle or at 30 mph prior to testing CARB developed the acceleration simulation mode test The Repair Grade (RG-240) is similar to the I/M 240 test but more economical

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The report shows the amount of gases emitted and the cutpoint Look at the gases, loads, and speeds when over the cutpoint Consider correlations between gases and systems Interpreting the Results of an I/M Test

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Exhaust Analyzer Uses a sample hose in the exhaust A four-gas analyzer measures HC, CO, CO 2, and O 2 A five-gas analyzer measures NOx in addition Limits are set by vehicle year and model, local and state laws

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Exhaust Analyzer

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Interpreting the Results HC and CO are a direct indication of engine performance High NOx readings indicate high combustion temperatures High CO 2 indicates complete combustion O 2 should be low and is inversely related to CO

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

General Guidelines HC is a result of incomplete combustion High CO indicates excessively rich When CO goes up, O 2 goes down O 2 is unchanged by the catalytic converter NOx is lowest when CO and HC are lowest An extremely rich mixture will cause high HC, CO, and O 2

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check Technician A says rich exhaust will have a high HC reading. Technician B says a rich exhaust will have a high CO reading. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Basic Inspection Battery voltage Air filter/cleaner Charcoal canister Idle speed Base timing Fuel pressure Engine mechanical condition Electrical and vacuum connections PCM grounds EVAP, EGR, and PCV hoses Air tightness of fuel tank, filler, and cap MIL and DTCs

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. OBD II Monitors Each requires one or more diagnostic tests May be continuous or non-continuous and only when certain enabling criteria are met If a system or component fails a DTC is stored and MIL on within two drive cycles A pending DTC is stored when a concern is initially detected

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Monitor Status

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. OBD II Monitors (Cont.) Many I/M inspections mandate checking OBD II monitor status A DTC may prevent the monitor from running If no DTC is present but the monitor is incomplete, the vehicle should be operated as recommended to enable the monitor

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. If gasoline odor is present, check the EVAP system Fuel or fuel vapor leaks should be repaired immediately Check EVAP monitor status Evaporative Emission Control System Diagnosis and Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Visual Inspection of EVAP

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EVAP Monitors A leak can generate multiple DTCs All EVAP DTCs require two trips Vapor purge monitored by pressure sensors Enhanced EVAP systems monitor flow rate Newer systems can detect leaks 0.020” or 0.5mm

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Diagnosis System purging at idle can cause: – Rough idle Cracks in hose or canister can cause: – Gasoline odor around vehicle – Trouble codes on OBD II systems A loose fuel filler cap can cause: – Trouble codes on OBD II systems

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Purge Test Run engine to normal operating temperature Connect purge flow tester With engine running, record purge flow rate and volume Most vehicles will have a flow of 25 liters during the time for the I/M 240 test

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Leak Tests Pressure decay tests checks for leaks Usually pressurize system at very low pressure with nitrogen Make sure fuel tank is at least half full Normally conducted with the EVAP service port Leaks can be found by spraying soapy water

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Scan Tool Use

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EVAP Service Port

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Smoke Test Nearly all OEMs recommend this method The leak is identified by the escaping smoke The canister vent port must be blocked off The solenoid may be closed through scan tool commands

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Smoke Testing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Cap Tester

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Service involves inspection, functional tests, and replacement of faulty parts Fixed orifice tubes should be cleaned Match replacement PCV valve part numbers Newer valves have locking devices to prevent leaks PCV System Diagnosis and Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. PCV valve stuck open can cause: – Lean air/fuel mixture – Rough idle – Stalling PCV valve stuck closed can cause: – Oil in the air cleaner – Moisture or sludge in the oil – Oil leaks Consequences of Faulty PCV Systems

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Visual Inspection Can be located in several places, most commonly in a valve cover Check hoses and PCV grommet Inspect air cleaner for oil

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Check for vacuum to valve Shake valve and listen for rattle Some manufacturers recommend checking for air flow through the valve Pinch off vacuum hose to valve and listen for it to click Measure CO and O 2 exhaust readings with valve in and out Functional Checks of the PCV System

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Knowledge Check Describe two methods of testing the EVAP system.

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Most common is a blow-by filter Inspect and clean as necessary If plugged, pressure will increase in the crankcase Diesel Crankcase Ventilation Systems

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Measuring Crankcase Pressure Engine at normal operating temperature Connect a water manometer to oil dipstick If reading is above 1 inch-H 2 O, check crankcase valve and/or cylinder leakage If less, bring engine to 2000 RPM If pressure drops to negative 4 – 5 inches, the valve is good

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR valves are calibrated for each engine Performance can be affected by too much or too little EGR flow Too little flow can cause engine overheating, detonation, and excessive NOx EGR System Diagnosis and Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR stuck open can cause: – Rough idle – No-start, surging, or stalling EGR stuck closed (or system inoperative) can cause: – Detonation (spark knock) – Excessive NO X emissions – Poor fuel economy EGR System Conditions and Symptoms

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR monitor activated by input from ECT, IAT, TP, and CKP DPFE and vacuum regulator circuits checked for opens and shorts Hoses are checked once per drive cycle EGR flow checked continuously at idle MIL on if test fails two consecutive drive cycles Scan Tool

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR Testing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Scan Tool (Cont.) Too much EGR flow on MAP systems will increase manifold pressure Excessive EGR flow will cause negative fuel trims Too little EGR flow will cause positive fuel trims

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

EGR System Troubleshooting Check engine mechanical condition, fuel and ignition systems Sticking valves, obstructions, and loss of vacuum Check vacuum hoses for leaks, kinks, cracks, and flexibility

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR Valves and System Testing Check vacuum supply for vacuum operated valves Supply vacuum and observe diaphragm Digital EGRs can be checked with scan tool A scan tool may be used on linear valves

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR Testing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Checking EGR Efficiency Use a five-gas analyzer Raise engine speed to 2000 RPM Watch NOx readings – should be below 1000 ppm If above 1000 ppm, the EGR system is not performing properly

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Electronic EGR Controls EGR valve position sensor is a potentiometer and subject to wear Position sensor can be checked with a DMM or scope Should show a clean pattern as the valve is opened and closed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Electronic EGR

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. EGR Vacuum Regulator (EVR) Tests

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Remove and place in a container of oil Insert a thermometer and heat the oil Connect ohmmeter leads to sensor terminals Sensor should have specified resistance at various temperatures Exhaust Gas Temperature Sensor Diagnosis

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Diesel Engines High Pressure – Capture exhaust gas before the turbo and redirects it back into intake air Low Pressure – Collects exhaust gas after the turbo and PM filter and returns it back to the intercooler

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check When testing an EGR system with a scan tool, the EGR is commanded open but the engine speed does not change. Technician A says the EGR may be faulty. Technician B says the EGR passages may be plugged. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Catalytic Converter Diagnosis Oxygen store is one convert function and is a good indicator of efficiency OBD II systems compare oxygen content pre and post converter Catalyst monitor runs after HO 2 S monitor

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Catalytic Converter Diagnosis (Cont.) When the HO 2 S signals become alike and stay that way for a number of drive cycles, a DTC will be set

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. A converter DTC does not always mean the converter is faulty: – Small leak in secondary AIR system – Small misfire causing extra oxygen in exhaust – An exhaust leak downstream of the front HO 2 S Catalytic Converter Diagnosis (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. 0 2 Storage Test – Use exhaust analyzer to check 0 2 content – Should be about 0.5 to 1 percent Converter Efficiency Test – Use exhaust analyzer to check CO 2 content – Should be greater than 11 percent Converter Diagnosis

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Measuring Actual Converter Efficiency Measure emission levels pre and post converter Run engine at 2500 for at least two minutes and record HC and CO Remeasure at tailpipe and compare readings A good converter should have at least 70% efficiency

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. AIR System Diagnosis and Service Most systems are computer controlled The AIR monitor checks the electrical circuit and the ability to inject air into the exhaust

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. AIR System Diagnosis and Service (Cont.) Enable the AIR system and watch HO 2 S voltages – low readings indicate AIR system is operating

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Noise Diagnosis Leaks from the exhaust can cause a hissing noise The AIR pump shaft seal can cause an air leak Rattling from the pump when running can be from worn isolator mounts

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. System Efficiency Test When operating correctly, HC, CO, and CO 2 are decreased and O 2 is increased Run the engine at 1500 RPM with AIR enabled and note exhaust readings Disable the AIR system and record the exhaust readings and compare

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. AIR Component Diagnosis AIRB Solenoid and Valve – Start engine and listen for air being exhausted – During warm-up, check for air flow from hose to exhaust ports – At normal operating temperature, check for air to the catalytic converter Combination Valve – Check using hand held vacuum pump

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. AIR Component Diagnosis (Cont.) Check Valve – The one-way check valve lets air in but closes to keep exhaust from leaking out – Check with an exhaust analyzer – Any amount of CO or CO 2 indicates a leak