smog check

Smog Check

2011 Update

Goals of this Class

• Inspection Procedures• Aftermarket Parts• OBD II Practical Processes• Catalytic Converter Testing• Final Examination

Smog Check Inspection Procedures

Pre-Test Check List

• Ensure all test equipment is up-to-date and maintained

• Check for vehicle test restrictions and inform consumer if any apply

• Ensure consumer is provided a proper estimate

• Ensure vehicle is safe

Page 1

Vehicle Identification

• Technician Access• Vehicle Identification Information

– Using the bar code scanner– Using vehicle registration documents– VID communication failures

• Each tech is responsible the accuracy of the test

Page 2 & 3

Emissions Tests

• Before Test Conditions– No safety hazards– Vehicle is at operating temperature– All vehicle accessories are off– Verify proper test (TSI or ASM)– Verify tires are dry– Verify vehicle fits on dyno– Verify vehicle is restrained properly

Page 5

Emissions Tests

• Before Test Conditions (cont.)– Verify cooling fan is positioned correctly (72°)– Connect RPM pick-up– Insert tailpipe probe– Lower Hood (ASM)

Page 5

Emissions Tests

• Acceleration Simulation Mode (ASM)– 50/15 & 25/25– Incompatible vehicle designs

• “Non-disengagable” traction control• Full time all wheel drive• Too large to fit dyno• Hybrid vehicles• Heavy Duty Vehicles with a drive axle weight that

exceeds 5,000 pounds when vehicle is unloaded

Page 6

Emissions Tests - Preconditioning

• Vehicle shall be warmed to operating temperature, and idle for at least 3 minutes immediately before starting the emissions tests

• Technicians shall not attempt to superheat the catalyst

• Refer to the Smog Check Inspection Procedures Manual, Page 5

Emissions Tests

• ASM Gear Selection– Automatic (Drive)– Manual (Second gear)

• TSI– 2500 RPM for 30 seconds– Idle mode

• Refer to the Smog Check Inspection Procedures Manual, Page 7

Page 7

BAR Technician Performance Evaluation

Bureau of Automotive Repair

11

Inspection Quality

BAR’s strategy to clean the air relies on technicians properly failing those vehicles that should fail.

Roadside testing and the Sierra Report both demonstrate that many vehicles that should fail the Smog Check inspection are not being failed appropriately.

12

Inspection Quality

What are the most common ways to get a failing vehicle to improperly pass an inspection?

– Not perform required elements of inspection (e.g., timing, fuel cap, LPFET, OBDII)

– Reset OBDII systems prior to test to clear DTC’s– Over-condition ASM test vehicles (restart, abort tests)– Drive an ASM inspection in the incorrect gear– Direct cheating (clean piping, clean plugging, etc).

13

Inspection Quality

• Test deviations measure departures from required inspection procedures as appropriate to the vehicle– Failing to inspect ignition timing– Failing to inspect the fuel cap– Failing to perform the LPFET test– Failing to perform the OBDII test– Resetting OBDII systems without making repairs to get

vehicle to “slip” through– Restarting or Aborting tests to provide second chance

(over-conditioning)– Using the wrong transmission gear for the ASM test

14

Inspection Quality

• Test Deviations – Ignition Timing– Measures the rate at which each

station fails to perform a timing inspection when most technicians indicate that the timing is adjustable

– Deviation flag set when a station’s rate is above average for similar vehicles

15

Inspection Quality

• Test Deviations – Fuel Cap– Measures the rate at which

each station fails to perform a fuel cap pressure test when most technicians indicate that the fuel cap is testable


16

Inspection Quality

• Test Deviations – LPFET– Measures the rate at which each

station fails to perform the LPFET when most technicians indicate that the vehicle’s evaporative system is testable


17

Inspection Quality

• Test Deviations – OBDII Test– Measures the rate at which

each station fails to perform a OBDII test when most technicians indicate that the vehicle’s OBDII system is testable

– Deviation flag set when a station’s rate is greater than average for similar vehicles

18

Inspection Quality

• Test Deviations – OBDII Reset– Measures the rate at which

each station passes vehicles with the exact number of necessary OBDII readiness monitors set in order to pass

– Deviation flag set when a station’s rate is greater than 125% of average for similar vehicles

19

Inspection Quality

• Test Deviations – ASM Restart– Measures the rate at which

each station restarts ASM inspections

– Deviation flag set when a station’s rate is greater than 125% of average for similar vehicles

20

Inspection Quality

• Test Deviations – Inspection Abort– Measures the rate at which

each station aborts inspections

– Abort flag set when a station’s rate is greater than 5% of total inspection starts

21

Inspection Quality

• Improper Gear Selection – ASM test– Manual Trans – test in 2nd gear (Page 7, Smog Check

Manual)– Auto Trans – test in drive (Page 7, Smog Check Manual)– Engine RPM during tests indicates when vehicle in

incorrect gear– RPM limits assigned by specific vehicle configuration

• Example: 1989 Toyota Camry, 2.5l auto trans• Limit = 90 percentile + 300 rpm

– Stations disqualified if more than 2% of vehicles were certified with RPM beyond limits in either ASM test mode

22

Inspection Quality

• Improper gear selection – example of limit

23

Engine RPM, ASM 5015VLT Row 40711

1989 Toyota Camry, 2.5l Automatic

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Limit = 90th Percentile + 300 rpm

Inspection Quality

• Improper gear selection example:– 1989 Toyota Camry, 2.5l automatic

24

Inspection Quality

• Improper gear selection example:– 1989 Toyota Camry, 2.5l automatic

25

Inspection Quality

• Comparative Failure Rate (CFR)– serves as a basic litmus test for whether a technician is failing vehicles that should fail. – Compares the technician’s failure rate to the

industry failure rate for the same type of vehicle.

26

Inspection Quality

• Comparative Failure RateThe technician’s failure rate must be greater than or equal to 75% of the statewide failure rate for similar vehicles.

27

Inspection Quality

• While the performance metrics discussed thus far will push performance higher, they can be manipulated– Examples – RPM simulators, entering vehicles as

testable for certain program elements (e.g., LPFET) and then faking the test results, etc.

• Solution: Introduce a robust long-term metric to ensure quality over the long haul

28

Inspection Quality - FPR• “Follow-up Pass Rate” (FPR) correlates current

cycle pass rates to quality of inspection in the previous cycle– Comparison made across similar vehicles (Model year,

make, model, engine size, transmission type, body shape, time since last inspection, previous inspection result, vehicle odometer)

29

Inspection Quality - FPR• Conceptual example: two hundred 1995 5.0L Ford

Mustangs were high-emitting vehicles in the last inspection cycle. – Half were clean-piped, shifted into the wrong gear, or

over-conditioned in order to pass their last inspection. – The other half were properly inspected, failed, and then

repaired to legitimately pass their last inspection. • Vehicles from which group are more likely to pass

in the current cycle?

30

Inspection Quality - FPR

• FPR scores reflect probability that a technician’s vehicles pass at a higher rate than average in the next inspection cycle– Scores Range from 0 to 1– 0 score means we are 100% confident that

performance is below average– 1 score means we are 100% confident above

average– 0.5 means we don’t know conclusively due to

insufficient test history– New or low-volume technicians assigned 0.5 score

31

Technician Feedback

• BAR will set up a secure Web page to view status.

• Will provide technicians feedback on their performance

• Password protected so technician may view only their own data

32

UNDERSTANDING AFTERMARKET PARTS

Covered Topics• How to recognize aftermarket parts during a

visual inspection • Parts labels, Executive Orders (EO) and links to

verify parts• Pre 1/1/2009 catalytic converter labeling• Post 1/1/2009 catalytic converter labeling• Other approved aftermarket parts examples• Modified aftermarket parts examples

Visual Inspection• Vehicle Emission Control Requirements: Technicians must

use all available information necessary to determine the vehicle’s emission control requirements, including but not limited to:

• The under-hood emission control label (see section 1.3.2)• The current emission control application guide• The emission control repair manuals• The emission component location guides• The manufacturer emission control recalls and TSB’s

(Technical Service Bulletins)• The vacuum hose routing diagrams• The California Air Resources Board (CARB) aftermarket

parts listings, the aftermarket part label (see section 1.3.2), and any reliable vehicle manufacturer sources.

Visual Inspection• If a vehicle is equipped with parts that modify the

original emission control configuration, technicians must verify whether those parts are CARB approved or exempted. If the installed parts are not CARB approved or exempted, and the original emissions control configuration has been modified, the corresponding emission controls are considered “Modified” and the vehicle shall fail the inspection

Smog Check Reference Guide

• Aftermarket Parts Verification Guidelines Gasoline and Diesel – Appendix G

– Aftermarket Parts Definitions– Category I lists parts that do not require EO

verification – Category II lists parts that require EO verification– Diesel Quick Reference

Visual Inspection(cont.)• To verify CARB approval or exemption, technicians

must check the Aftermarket Parts Label affixed either directly to the part or near the part. This label contains a CARB Executive Order (EO) number that can be used to verify approval or exemption. With the EO number, reference the CARB EO parts listings and/or part manufacturer catalog

• The CARB EO part listings and information about catalytic converters can be found on the CARB website www.arb.ca.gov. Technicians may also contact ARB at (800) 242-4450 if they need additional information

http://www.arb.ca.gov/

Aftermarket Parts Label• Note: A missing or illegible APL does not

constitute an inspection failure. In cases where the label is missing or illegible, the technician may proceed with the inspection, provided the parts can be confirmed as CARB approved or exempted by comparing the part number marked on the part with the CARB EO parts listings or the parts manufacturer catalog

Web Links • AFTERMARKET PARTS DATABASE OF EXECUTIVE

ORDERS• CURRENT LIST OF AFTERMARKET CATALYSTS• PRODUCTS IN PROGRESS LIST (DIESEL)• LIST OF AFTERMARKET CATALYTIC CONVERTERS

IN COMPLIANCE WITH NEW REGULATIONS• APPENDIX G – AFTERMARKET PARTS

VERIFICATION GUIDELINES http://www.arb.ca.gov

http://www.smogcheck.ca.gov



NON-ORIGINAL EQUIPMENT CATALYTIC CONVERTERS

•All Non-original catalytic converters must be CARB approved/exempt and are labeled with information necessary to ensure that installations comply with California law.

Catalytic Converter Labeling• Catalytic converters installed before January 1, 2009New aftermarket catalytic converters and certified used catalytic converters can be identified by a permanent stamp or label on the shell of the converter. The label/stamp should be in the following U.S. E.P.A. format: T/CA/MC XXXX YYYY. The labels do not include the EO number

T/CA/MC XXXX YYYY• T: Either “N” (for new aftermarket converters), or “U”

(for certified used converters). ARB staff has found that this character is sometimes omitted on new aftermarket converters

• CA: Indicates that the converter has been ARB approved

• MC: A two character code for the converter manufacturer

• XXXX: The converter’s part or series number. The number may be longer than 4 digits

• YYYY: The date of manufacture. The first two digits indicate the month, and the last two the year

N = New Aftermarket

CA = ARB Approved in

California

TA = ManufacturerSee Website Database The Converter Part/Serial Number

Manufacture Date

Month/Year09 05

Pre- 1/1/09 Labeling Example

This Table Lists Valid Manufacturer Codes For California

CODE MANUFACTURER CODE MANUFACTURER

AD Advanced Car Specialties (RiteCat). ES ESW America, Inc.

AE The Automotive Edge (Hermoff) ET Emico Technologies, Inc.

AT AirTek, Inc. (Catco) LP LaPointe Exhaust System Equipment

BN Brown Recycling & Manufacturing, Inc. MC Miller Catalyzer Corp

BO Bosal Mexico SA DECV MM Maremont

CE Car Sound Exhaust System, Inc.(Magnaflow)

PA Perfection Auto Prod. Corp

CT Valina, Inc. (CarTex). PP Products For Power

CV Cateran Pty Ltd. TA Walker Manufacturing

EM Eastern Manufacturing Inc. TD TRI-D Industries Inc.

EQ Equipo Industrial Automotriz S.A. de C.V.

TP Tested Products (DEC)

Catalytic Converter Labeling • Catalytic converters installed on or after January 1,

2009

Meet more stringent requirements

Labels include the EO number in large font, presented in the following format:

D-XXX-XXYYYYYY

ZZZZ

D-XXX-XX =

This is the ARB approval number for the converter (known as the “EO number”). Every EO number will begin with “D”. The first three X’s will be a 3 digit number corresponding to the manufacturer. The last two digits will be the specific approval number for the manufacturer. The EO number can be used to obtain information about the approval status of the converter on ARB’s website in the same manner that other aftermarket add-on and performance parts can be looked up. The website address is:http://www.arb.ca.gov

YYYYYY =The part number for the converter (assigned by the manufacturer)

ZZZZ =

The date of manufacture. The first two digits indicate the month, and the last two the year.

Decoding Catalyst Labels


Legal Converters With Laser Printing And Plate ID

CONVERTER WITH LASER

PRINTINGSEE EO#D 280-73

CONVERTER WITH PLATE ID

SEE EO#D 280-77

Labeling ExampleARB EO# D-193-86 Manufacturer Assigned part

# 36104

Manufactured March 200903/09

Resource Examples

Enter the EO# here: D-193-86

Left Click Here

This screenshot shows where to enter the replacement part EO number into the ARB search

engine.

EO # D-193-86 Entered Into ARB Search Engine

A FEW EXAMPLES OF OTHER APPROVED AFTERMARKET

PARTS

Fuel Injection Conversion Kit With EO - 1979 Jeep Cherokee

CARB EO# D452-2

1979 Jeep Carburetor is replaced with a TBI unit

Aftermarket Air Intake with EO - 2003 Mitsubishi Eclipse

AFTERMARKET AIR INTAKE

SYSTEM

2003 Eclipse EO Sticker Attached Underhood To

Vehicle Body

This is just one example of many CARB approved aftermarket parts.

Then Scrolling Down On The EO Page We Find That The Vehicle And Engine Are LISTED.

IF POSSIBLE, MATCH A PART

NUMBER WITH THE PART. THIS AIR INTAKE SYSTEM

WOULD BE A PASS ON THIS VEHICLE.

SOME EXAMPLES OF “MODIFIED” AFTERMARKET PARTS

Adjustable Cam Gears

Aftermarket Headers With No EO 1995 Saturn Sl 1.9L

Aftermarket Air Intake With No EO 2003 Toyota Celica

Aftermarket Air Intake With No EO 99 Honda Civic

Aftermarket air intake system- no EO

What to enter into the EIS? The Other Emissions Related Components category

encompasses emission control systems that are not otherwise addressed in the visual inspection menu. Other Emission Related Components include, but are not limited to: – Add-On Aftermarket Parts – Cylinder Heads – Exhaust Manifolds – Intake Manifolds – Superchargers– Thermal Reactors– Timing Gears and Pulleys– Turbochargers

Other Emissions Related Components

• If a vehicle fails the Other Emissions Related Components category of the visual inspection, technicians must document, on the VIR, what emissions system failed.

• Note: The Other Emissions Related Components field is also used to capture failed test results for the Visible Smoke Test. For more information, see Smog Check Inspection Manual section 1.3.4.

Notations on the repair order

• It is necessary to make notations on the repair order of any aftermarket devices that are entered into the EIS “other” category.

• If there is no Executive Order (EO), enter as “Modified”.

California Code of Regulations3340.41

• (a) Test Report Requirements• (b) EIS Access & Tampering• (c) Entering Information into the EIS• (d) Repair Procedures• (e) Testing Directed Vehicles

OBD II Practical Processes

OBD II Procedures

• Circuit Testing• Understanding Sensors• Understanding Outputs and Actuators• General Diagnostics Strategies• Readiness Monitors• Mode $06

Circuit Testing

Sensors

Understanding Sensors

• The Powertrain Control Module (PCM) performs two distinctive functions – Performs Voltage Drop Tests – Performs Logical Decisions based on the voltage

drop test results.

Sensors• There are three categories of sensors;

– Variable Resistance • Has an internal resistor, the resistance value changes

with Temperature, Pressure, Air Flow or Position– Voltage Producing

• Produce voltage based on engine detonation/pinging, oxygen content of the exhaust, rotation of the Crankshaft, Camshaft, Wheels or Vehicle Speed

– Switching Type• A switch type sensor input is a clear high or low signal,

depending on whether the switch is open or closed

Analog Signals• A variable signal that is

proportional to a measured quantity.

• Analog signals are produced by sensors that mechanically change resistance to deliver variable voltage signals. Analog signals are produced by variable resistance type sensors and voltage producing type sensors

Types of Sensor Signals

Digital Signal• Digital signals are On – Off voltage

pulses, typically 2.5, 5.0 or 12 volts.

• AC voltage generating sensor signals are converted into digital signals. This conversion process takes place by an Analog / Digital Converter.

Types of Sensor Signals

Types of Sensors

• Hall Effect – Monitors the speed of a rotating component.

• Permanent Magnet – Monitors the speed of a rotating component

• Pressure – Monitors pressure within a component or system.

• Position – Monitors the position of a component.• Thermistors – Measure temperature within a

component or system

• Are frequently used where accuracy and fast response are important

• Contain a powerful magnet, as the magnet passes over a dense portion of the trigger wheel the 5 volts is pulled to ground (.3V) through a transistor in the sensor, when the magnet passes over a notch in the trigger wheel the 5 volts is restored.

Hall Effect Sensors

Types of Hall Effect Sensors used on today’s automobiles

are:

•Cam Position Sensors (CMP Sensors)•Crankshaft Position Sensors (CKP Sensors)

5 Volts

0 Volts

Hall Effect Sensors

• Consists of a permanent magnet surrounded by a winding of wire

• When a metallic (iron or steel) is passed extremely close the magnet, the magnetic field is interrupted and a small amount of AC voltage is induced into the windings

• The induced AC voltage amount varies by:– Speed of interruption– Distance between magnet and metallic object and– Strength of magnet.

Permanent Magnet Sensors

Types of Permanent Magnet sensors used on today’s automobiles are:

•Cam Position Sensors (CMP Sensors)•Crankshaft Position Sensors (CKP Sensors)•Wheel Speed Sensors (WSS Sensors)•Vehicle Speed Sensors (VSS Sensors)•Transmission Input & Output Speed Sensors

Permanent Magnet

Surrounded with wire

Permanent Magnet Sensor

Reluctor Wheel attached to Crankshaft

Signal from fast interruption of magnetic field

Signal from slow interruption of magnetic

field

Permanent Magnet Sensors

Pressure Sensors and Switches• Atmospheric pressure is 14.7 PSI or 29.92 inHg @ sea

level• Pressure sensors monitor the pressure differential

between atmospheric pressure and the pressure within a component or system

• Pressure sensors also monitor barometric pressure (atmospheric pressure)

• Pressure sensors are three wire sensors; a three wire sensor has a reference voltage wire (vref) from the PCM, a ground and a signal voltage wire

• Pressure Switches are typically a two-wire “on/off” switch located in a location where fluid pressure monitoring is critical

Pressure Sensors and Switches

Types of Pressure sensors used on today’s automobiles are:

•Manifold Absolute Pressure Sensor (MAP Sensor)•Fuel Tank Pressure Sensor (FTP Sensor)•Barometric Pressure Sensor (Baro Sensor)•Delta Pressure Feedback EGR Sensor (DPFE Sensor)

Intake Air Flow Sensors

• Two ways to measure intake airflow– Speed Density

• Measures intake air flow by sensing changes in intake manifold pressure using a pressure type sensor

– Mass Airflow• Measures the volume, density and on some the

temperature of the incoming air using a vane type or hot wire type sensor

Flap – Type or Vain Air Flow Meter

Vane Air Flow Sensor• Utilizes an air flow door (flap) connected to a

potentiometer

Hot Wire Air Flow Sensor

• The most common type of Mass Airflow Sensor (MAF)

• All hot wire type sensors use the same operating principle

• Incorporates a small orifice inside the main body, as air passes through the MAF a steady flow also passes through a small orifice

• Inside there are two wires, a compensating wire and a sensing wire.


Hot Wire Air Flow Sensor Compensating Wire

• The compensating wire is a thermistor that has a small amount of current passing through it.

• As the volume of air increases “cooling the thermistor” the resistance (Voltage) of the thermistor increases.

• The voltage represents the temperature of incoming air.

Hot Wire Air Flow Sensor Sensing Wire

• The sensing wire is maintained at a constant temperature, approx 170° to 212°F (depending on manufacturer) above the temperature of the compensating wire

• This temperature is maintained by varying the current flowing through it


• As air flow increases, current increases• As air flow decreases, current decreases• The amount of current flow = amount of air flow

Amps=Air AmpsAir

Position Sensors

• Provide linear or angular measurement in relation to the position of that specific item or component . There are two types of position measuring sensors they are:– Rheostat– Potentiometer

Rheostat

• Is a two wire sensor • Most common uses

of the rheostat is for the Fuel Level Sender

Fuel Gauge

Rheostat

IGN GRD

Potentiometer

• Most common type of position sensor• Contains a mechanical arm that is attached a

moving component (throttle plate, accelerator pedal, airflow door, etc.) which causes it to slide across a fixed resistor within the sensor

Potentiometer

Ground

Reference Voltage

Signal Return

Potentiometer

• The potentiometer functions as a voltage divider.

Thermistors

• Thermal resistors are used for sensing temperature

• Two basic types of thermistors:– Positive Thermal Coefficient (PTC) – Negative Thermal Coefficient (NTC)

• Most common type used for sensing air temperature and fluid temperatures

Positive Thermal Coefficient (PTC)

• Temperature and resistance (Voltage) are directly proportional

Negative Thermal Coefficient (NTC)

• Temperature and resistance (Voltage) are inversely proportional

Oxygen Detecting Sensors

• Located in the exhaust stream and provides feedback information to the PCM about the oxygen content in the exhaust

• Generates its own voltage signal• There are three types of oxygen sensors

– Zirconium– Titania– Air Fuel Ratio

Oxygen Sensor Construction

• Has a center element made of a ceramic material called zirconium

• Two platinum electrodes make up the inner and outer surfaces of the center element

• Internal temperature must be kept above 600⁰F

O2S Voltage Generation• O2 sensor operation

Lean Rich

Air Fuel Ratio Sensors

• They perform the same function as zirconium O2 sensors with some added benefits– Allow a more accurate fuel control over a much

wider range (10.1 – 20.1 A/F Ratio)– Operational within 10 seconds from a cold start,

thereby reducing cold start emissions.– Inform the PCM exactly how rich or lean the A/F

ratio is

A/F Sensor Construction1. Exhaust Guard2. Ceramic Seal Assembly3. Sensor Housing4. Ceramic Support Tube5. Planar Sensor Element6. Protective Cap7. Sensor Wires

Planar Sensor Element• The air fuel ratio sensor

contain two zirconium O2 sensors, one to measure the oxygen content of the exhaust (zirconium Sense Cell) and another zirconium O2 sensor (zirconium pump cell) to control the zirconium sense cell. Also contains a heater element.

• The PCM monitors the exhaust in the exhaust sense chamber, using the zirconium sense cell. (High or Low oxygen content)

• The PCM will either add or remove oxygen atoms to or from the exhaust sense chamber to keep the sense cell at lambda of 1 (14.7.1). This is accomplished by reversing the polarity of the voltage to the zirconium pump cell.– Higher than 450mv – Oxygen is added– Lower than 450mv – Oxygen is removed

• The amount of oxygen added or removed informs the PCM exactly how rich or lean the A/F ratio is.

Planar Sensor Element

Piezoelectric Sensors• The knock sensor is a piezoelectric sensor• Detects vibrations arising from combustion knock

caused by low octane fuel, high engine temperatures, detonation and or pinging

• Allows the PCM to control ignition timing for the best possible performance while protecting it from potentially damaging detonation

Outputs/Actuators

Outputs / Actuators

Powertrain Control Module

(PCM)

Operating Parameters Sensed

MAF SensorMAP SensorECT SensorIAT SensorCKP SensorCMP Sensors 1 and 2TP Sensors 1 and 2APP Sensors 1 and 2EGR Valve Position SensorKnock SensorHO2S 1/1, 2/1 and ½PSP SwitchBPP SwitchAC On/Off RequestAC Pressure SensorFuel Level SensorFuel Tank (EVAP) SensorVSS SensorTrans Fluid Temperature SensorTurbine Speed SensorTrans Range Switch

Output Components Controlled

Fan Control RelayFuel Pump RelayAC Clutch RelayThrottle Actuator Control MotorMalfunction Indicator LampCamshaft Position SolenoidsEGR ValveFuel InjectorsIgnition CoilsGenerator FieldEVAP Canister Purge SolenoidEVAP Canister Vent SolenoidTorque Converter Clutch SolenoidTrans Pressure Control SolenoidTrans Shift Solenoid

Types of Outputs/Actuators

• Actuators are devices that perform work, such as:– Motors– Stepper Motors– Relays– Solenoids – Coils– Lamps

Output Controls• These devices are controlled by the PCM simply by

turning them “On” and “Off”, often by providing and removing ground

PCM

PCM

Supplies

Ground

Output Controls• There are several types of output signals from

the PCM to control actuators; they are:– Frequency– Simple ON and Off switch type signal– Duty Cycle type signal– Pulse Width Modulated type signal

Frequency• Frequency is a measurement of how many times a

pattern repeats itself in one second• Measured in Hertz (Hz)• Frequency is measured from the beginning of a pattern

to the beginning of the next

Off

On

Simple Off and On• Actuator is either completely turned on or off

Off

On

Duty Cycle

• Duty Cycle is the measurement of time an actuator is turned on versus the amount of time it is turned off

• Measured in Percentage (%)

• The measurement of duty cycle is the amount of frequency divided by the “On Time”. Using the example below; the frequency is 12.5Hz, the amount of time the lamp is “On” 50.0Hz (12.5Hz ÷ 50.0Hz = 25% Duty Cycle)

Duty Cycle

Pulse Width Modulation

• Pulse refers to turning an actuator on and off• Width refers to the amount of time the actuator is

“On”• Modulation refers to the fact that the actuator is

being controlled, or modulated, over a period of time• Pulse Width Modulation (PWM) is different from

Duty Cycle in that both frequency and On time varies. Duty Cycle signal frequency never changes

• Example, the Fuel Injector is turned on once per engine cycle, however as the engine RPM’s increase so does the frequency of turning the injector on and off. In the following illustration, the injector is turned on for 6.85ms and 146 times in one second (146.1Hz)

Pulse Width

Pulse Width Modulation

Actuators (Load Devices)

• Most actuators rely on the principles of electromagnetism

• Relays, Fuel Injectors, Solenoids, and Motors are examples of actuators that utilize electromagnetism for their operation

Motors• Most DC (Direct Current) motors contain four

main electrical components– Commutator

• Consists of two electrical contacts that are connected to the windings of the armature

– Brushes (Contacts)• Brushes are mounted in a position that allows contact with

the commutator and are the means by which the electromagnet receives voltage

– Armature• Consists of the electromagnet and a shaft on which the

electromagnet is mounted. It is also referred to as a rotor– Permanent Magnet

Stepper Motor• A stepper motor functions similar to a DC motor,

however the stepper motor is much more precise in its movement

• Common type of stepper motor is the Idle Air Control Valve (IAC)

Relays

• A relay is an electromechanical device that utilizes a small amount of current to energize an electromagnet that closes the contacts in a circuit carrying a higher amount of current

Solenoids• Solenoids are used to control the

mechanical operation of a component, or act as a valve to control gas or fluid flow

Transmission Pressure Control

Solenoid

Electronic Exhaust

Gas Recirculation

Valve (EGR)

Fuel Injectors

• The Coil is part of both the primary and secondary circuit

Secondary Windings

Primary Windings

Primary Control

Switch

Ignition Coils

LAMPS• A lamp contains a

resistor called a filament that emits light when current flowing through it

• The other type of lamp source is the LED (Light Emitting Diode), LED is a semiconductor light source that is mainly used as indicators, and in the automobile the MIL (Malfunction Indicator Lamp)

OBD II General Diagnostic

• The following are eight steps to follow as a suggested Diagnostic Strategy:1. Verify the customer’s concern2. Check the basics3. Check for diagnostic trouble codes4. Check and record freeze frame data5. Check PID Data and Monitor Status6. Review Repair History and TSBs7. Perform Repairs8. Verify Repairs

OBD II General Diagnostic Strategies

Verify The Customer’s Concern– Obtain as much information as possible from the

customer• When did it start to occur?• When does the condition occur?• Where does the condition occur?• How long does the condition last?• How often does the condition occur?• Have any repairs been done recently?• Are there aftermarket accessories on the vehicle?

– Establish a Baseline of the vehicle’s conditions, symptoms, and abnormal operation

Check The Basics– Mechanical systems, engine, transmission,

induction, exhaust and ignition systems, vacuum lines/hoses, fluid levels and condition, etc.

– Battery, Starting, and Charging circuits for proper operation, voltages, and voltage drops

– Sensors & actuators, and computer grounds– Steady and reliable reference voltage at all

sensors– Unplug suspect sensors with KOEO, and look for

related PID values to change– Compare possible PCM-default calculated values

to actual sensor voltage values

Review Repair History and TSBs

– Check for related TSBs for Service Procedure updates, as well as possible computer reprogramming

– Use other sources for specific service information either in print or electronically

– Keep accurate repair-related records• Diagnostics sequence• Record trouble codes

Diagnostic Trouble Codes

– Check for pending codes that may indicate a developing problem

– Check for codes stored in memory, even though the MIL may be OFF

– Check the exact definition of each code– Check the enabling criteria needed to run the

monitor and set the code

Freeze Frame– Look at the data and make an accurate record of the exact data that

is displayed– The data may not always send you to the exact problem, but it can

send you to the area of the problem

• Example #1: P0300• Example #2: If a P0402 excessive EGR flow code is stored, the vehicle

runs OK, and Freeze Frame looks normal, check the EGR system. “Good” Freeze Frame data is just as valuable as “Bad” data. The OBD II system sensed a problem, but a component in the system may not be “out of range” enough to set a specific DTC.

• Example #3: If a P03XX specific cylinder(s) misfire code that was stored under a high load and low RPM condition, and Fuel Trim looks good, check the ignition system. These conditions may indicate a rapid throttle opening during a loaded acceleration from a standing stop or low vehicle speed—exact conditions when ignition-related misfires occur.

Example #1•A P0300 misfire code is stored•LTFT is over +30% •Engine is misfiring (lean)•System is trying to add fuel

•Check fuel pressure•Possible causes

•Restricted fuel filter •Weak fuel pump•Clogged injectors, etc.•Vacuum Leak

Example #2•A P0402 excessive EGR flow code is

stored•Vehicle runs OK•Freeze Frame looks normal

•Check the EGR system. •“Good” Freeze Frame data is just as

valuable as “Bad” data. •The OBD II system sensed a problem,

but no component in the system was “out of range” enough to set a DTC

Example #3•A P03XX specific cylinder(s) misfire

code that was stored• Under a high load at low RPM

condition•Fuel Trim is normal

•Check the ignition system

These conditions indicate a rapid throttle opening during a loaded acceleration from a standing stop or low vehicle speed—exact conditions when ignition-related misfires occur.

PID Data and Monitor Status• Select the inputs & outputs to be monitored. Too many

PIDs slows the update rate of the scan tool. • Take a “Snapshot” of the data while the engine is

running or while driving the vehicle.• Look carefully at the inputs & outputs and their values.• Evaluate the information and compare PIDs one to

another.– Do MAP and BARO agree with the Key On Engine Off (KOEO),

and are they logical when the engine is running?– Are IAT and ECT the same when the engine is cold and KOEO?

IAT / ECT Comparison

• Engine Cold for accurate test results.

• Compare Coolant Temp with Intake Air Temp.

• ECT and IAT should be within manufacturer’s specifications.

Set your scanner up for PID comparison

– Check battery voltage at KOEO and KOER– Are IAC counts normal?– Review “Snapshot” data for unusual trends– Establish a Baseline of the vehicle

• Freeze Frame and Monitor Status establish a “Before” picture of the vehicle to compare “After” any repairs

• Keep your information simple but effective—Concentrate on critical PIDs

PID Data and Monitor Status

Perform Repairs

• Use the information gathered from the first six steps to assist you with your final diagnosis and repair

• Use the appropriate tools and equipment that are available to today’s technician to diagnose and repair the modern OBD II vehicle

Verify Repairs• Drive the vehicle until the specific monitor(s) run to

completion• Running the monitor(s) allows the system(s) to test

themselves• Once the monitor(s) run to completion, you can either

use Mode $06 Data and/or check for current or pending DTCs to assist in verifying your repair(s)

If the customer drives the vehicle to run the monitor(s), make them aware they are performing the drive cycle.

Make them aware that the OBD II system is designed to test itself as they drive.

OBD II and Fuel Trim

• The fuel trim values are very important, so they are included in Freeze Frame data.

• The data is shown as a percentage, either positive or negative, with 0% being neutral.

• Greater than 0% means that the system is adding fuel, while less than 0% means that the system is subtracting fuel.

Fuel Trim

• One of the most basic fuel system diagnostic procedures is to determine if the engine control system is operating in open or closed loop.

• Whatever the HO2S sensor does, the fuel trim corrects.

• For example, if the HO2S is sensing a lean condition, the STFT will begin to add fuel. As the STFT adds fuel, the LTFT will add fuel in order to lower the STFT.

Fuel Trim

Fuel Trim

• The STFT values are volatile, meaning they are erased every time the ignition key is switched off.

• The LTFT values are a ‘long-term adaptive’ strategy, which means that it changes based off of STFT, and will adjust to changes based off of all operating conditions over a period of time, such as wear and tear on the engine and its subsystems

• As the PCM determines that STFT and LTFT are at their maximum values and an air-to-fuel ratio imbalance exists (such as a vacuum leak or leaking injector), it will store a fuel trim related DTC.

• After establishing the loop status of the vehicle, evaluate the scan tool data, along with a five-gas analyzer, to determine if the PCM is providing a rich or lean correction, and the extent of any such correction.

Fuel Trim

OBD II Scan Tools

Scan Tool

• Data transmitted to the scan tool (PIDs) from the PCM include both digital and analog parameters.

• Digital parameters are often called ‘switch signals’, and are either on or off, low or high, or yes or no.

• Analog parameters are often called ‘modified signals’, and are values within a specific minimum-to-maximum range

• Voltage readings, speed signals, and temperature readings are just a few examples of PID data.

• All PIDs transmitted from the PCM to the scan tool has a specific value or signal range described in vehicle specifications.

• Knowledge of these PIDs specifications is needed during comparison to the scan tool readings to identify a system fault.

Scan Tool

• Scan tool readings that identify an open or a short circuit are among the easiest to recognize.

• For example, if a resistive sensor is displayed on a scan tool at or near the 5-volt reference voltage, the sensor circuit to the PCM may be open.

• If, however, the displayed value is at or near 0-volts, the circuit may be grounded

Scan Tool

• The PCM receives an analog or digital voltages from the input sensors.

• The PCM processes these signals, and sends a voltage signal or ground to output actuators.

• The scan tool displays these values (PID).

• Sometimes the scan tool displays a substitute value to compensate for a failed sensor.

Scan Tool

• The substitute or default value is based on pre-programmed OEM engineering software.

• A sensor failure may cause the PCM to ignore the signal from the failed sensor and operate on ‘substitute’ values stored in its memory.

• The PCM may transmit the ‘substitute’ values to the scan tool in place of the failed sensor signal.

Scan Tool

The technician is responsible for determining if substitution is displayed.

• For general powertrain control diagnosis, the following data parameters are among the most important:– System Voltage– Engine Speed– Engine Load– Vehicle Speed– Temperature– Pressure

Scan Tool

Generic OBD II Software

• Standardized scan tool modes of operation are mandated.

• Generic OBD II Software requires selecting Generic or Global OBD II from the scan tool menu.

• Standardized OBDII modes allow ‘generic’ scan tools to access the same subset of information from all cars

– Mode $01: Current parameter data (PIDs)– Mode $02: Freeze Frame data– Mode $03: ‘Confirmed’ emission-related DTCs

• DTCs that are (or recently were) commanding the MIL on– Mode $04: Clear DTCs and reset emission-related diagnostic

information– Mode $05: HO2S monitoring test results– Mode $06: Test results for non-continuously monitored systems– Mode $07: ‘Pending’ emission-related DTCs– Mode $08: Bi-directional controls (never required/implemented for

generic OBD)– Mode $09: Vehicle data (VIN, Calibration ID, etc.)– Mode $0A: ‘Permanent’ emission-related DTCs

• Stored when MIL commanded on• Cannot be erased by scan tool• Only erased by OBD system itself once monitor runs and passes

Generic OBD II Software

OEM Enhanced OBD II Software

• Enhanced scan tools include additional diagnostic capabilities.

• These capabilities include non-standardized and non-emission related information not available in the Generic OBD II Software.– Manufacturer specific DTCs– Manufacturer specific PIDs– Enhanced “Snapshot” functions– Bi-directional controls

• It is advantageous to use both the Generic and Enhanced protocols. – More data– Bi-directional controls– Identifying substituted values, etc.

OEM Enhanced OBD II Software

OEM Specific OBD II Software

• Performs OBD II related functions and interfaces with other vehicle computers.

• Most vehicles today has a multiplexed vehicle network system.

• Reprogramming functions.• Increased number of PID and DTC data, descriptions,

diagnostic tips, and strategies.• Up-to-date technical support and upgrades directly

from the vehicle manufacturer.

Manufacturer Specific Scan Tools/Software

OBD II 16-pin Connector• Pin #1: Discretionary to Vehicle Manufacturers• Pin #2: SAE J1850 Protocol “Hi Signal” [Data (+)]• Pin #3: Discretionary to Vehicle Manufacturers• Pin #4: Chassis Ground (Typically B-)• Pin #5: Sensor Ground (Typically B-)• Pin #6: ISO 15765 CAN “Hi Signal” [Data (+)]• Pin #7: ISO 9141-2 and 14230 Protocol “K-Line”• Pin #8: Discretionary to Vehicle Manufacturers

• Pin #9: Discretionary to Vehicle Manufacturers• Pin #10: SAE J1850 Protocol “Lo Signal” [Data (-)]• Pin #11: Discretionary to Vehicle Manufacturers• Pin #12: Discretionary to Vehicle Manufacturers• Pin #13: Discretionary to Vehicle Manufacturers• Pin #14: ISO 15765 CAN “Lo Signal” [Data (-)]• Pin #15: ISO 9141-2 and 14230 Protocol “L-Line”• Pin #16: Unswitched B+

OBD II 16-pin Connector

ASE L1 Composite Vehicle scan tool Data

• In this example there are 63 PIDs listed with Min/Max values for each data parameter listed

OBD II Monitors and

Mode $06

Monitors• Monitors are self tests of emission components or

systems.– Comprehensive Component– Misfire– Fuel Trim– EGR– O2 Sensor – O2 Heater– Catalytic Converter– EVAP– Air Injection Systems

Monitors

• Three or more incomplete monitors will cause a vehicle to fail smog inspection for 1996 to 2000 model year vehicles and 2 or more on 2001 and newer vehicles.

• Monitors are designed to run to completion during normal vehicle operation.– Enabling criteria must be met for monitors to run.– Enabling criteria for each monitor is different.

• Drive cycle would include enabling criteria for all monitors to run.

Mode $06 Data

• Mode $06 displays test results for non-continuous monitors.

• Mode $06 can give the results of a two trip monitor in one trip.

• Can confirm a successful repair after one trip. • Test results can indicate if a monitored system

is close to failing.

Terms Used in Mode $06 Data• TID = Test Identification – The system being tested (MIDs = Monitor

Identification in CAN systems)• CID = Component Identification – The component of the system

being tested.• TLT = Test Limit – To pass a test, a test value must be either a

minimum or maximum value ( or between a min/max value)• Hexadecimal ($) = Numeric/Alpha unit that indicates a specific

TID/CID or test value (Example: $02)• Raw Data = Numeric data indicating the actual test results.• Manufacturer’s Conversion Factor = Used to convert test data to

values that can be used to diagnose a system (volts, Ohms, amps, inches of mercury, etc.).

• Test Value = Actual test results.• Results = Indicates whether system/component either passed or

failed a test.• Limit Type = Test pass/fail limits

Mode $06 Data

• This scan tool shows the actual test results of the monitor

• Note the minimum and maximum parameters

**Non-Cont. Monitoring Test Result**ECU ID: $10 Test ID: $02 Component: $02Min: 12344 Max: 32768 Value: 11211

Results: Fail

Mode $06 Data

• A vehicle failed for a P0420 (CAT efficiency below threshold)

• A new CAT was installed and codes cleared. • Check the enabling criteria to run the CAT

monitor and run that drive cycle.

Vehicle failures due to monitors not run to

completion

Mode $06 Data

• Vehicle fails an ASM test for monitors not run.• Smog technician advises vehicle owner to drive the vehicle

for 50 miles.• Vehicle owner returns two days later with the same results

of monitors not running.• A diagnosis has been authorized.• Diagnosis has been made and no problems found. Vehicle

now referred to Referee.

Mode $06 Data

•Mode $06 shows TID $02 CID $60 has failed. (EVAP weak vacuum test 1) •Possible reason EVAP Monitor has not run

Mode $06 Data

• TID $07 CID $4D shows EGR passed at maximum

Mode $06 Data

• Code P0404 found in pending (Control Circuit)

Mode $06 Data

• Vehicle is at Operating temperature• Note ECT input is low at 111 degrees • Note fuel trims at negative -32.8

Mode $06 Data

• Testing the EGR circuit• Found a voltage drop of 1.57 volts on the ground side• Cause of pending code P0404

Mode $06 Data

•Testing the ECT circuit•Found 2.24 voltage drop on the ground side causing a higher voltage signal to PCM.•ECT sensor itself is within manufacture specs.•Causing Injector pulse width to increase.

Mode $06 Data

• The ECT and EGR harnesses have been repaired, and the codes and monitors reset. A drive cycle has been completed and all the monitors have run to completion. Vehicle now passes a smog check and vehicle owner feedback states vehicle is getting better fuel economy.

2011 BAR Update CourseCatalytic Converter Testing

Objectives

• The purpose of the catalytic converter

• The fundamental needs for proper catalytic converter operation

• Catalytic converter replacement requirements – CARB Installer’s List

• Causes of catalytic converter failures

• Pre-OBDII catalytic converter testing

• OBDII catalytic converter testing

The Catalyst

Catalysts are needed to reduce emissions to acceptable levels without dramatically reducing performance and fuel economy. This is true of HC, CO and NOx, but NOx is the emission that is most dependent on the catalyst for emissions compliance There are two types of catalysts:

•Reduction catalysts cause NOx to be reduced into O2 and N2.

•Oxidation catalysts cause HC and CO to oxidize with any available oxygen into CO2 + H2O.

*Unfortunately, oxidation will only occur when there is enough free oxygen, and reduction is very hard to achieve with the high oxygen levels that occur in lean burn operation.

The CatalystA catalyst can not clean up CO and HC unless there is enough oxygen in the exhaust.

Many catalysts can not clean up NOx unless the level of oxygen in the exhaust is very low.

There is no fuel mixture that allows CO, HC and NOx to all be catalyzed at maximum efficiency.

Gasoline Direct Injection (GDI) engines and Homogeneous Charge Compression Ignition (HCCI) engines operate under lean burn conditions frequently. Hybrid electric vehicles often operate their internal combustion engines for shorter periods of time that would prevent traditional catalytic converters from reaching operational temperatures.

The Catalyst

Many late model cars depend heavily on the catalyst to reduce NOx at extremely high levels (95+%). This simply is not possible unless the oxygen level is low enough. If carbon deposits or other problems increase the exhaust oxygen level, a perfectly good catalyst will operate at reduced efficiency.

Some late model cars depend on the catalyst to clean up over 99.3% of their NOx emissions.

This will only occur if the exhaust oxygen level is very low.

Many minor problems can increase exhaust oxygen levels and inhibit catalyst efficiency.

Catalyst Approval Criteria

As of January 1, 2009, CARB approval/exemption requirements for all aftermarket replacement catalytic converters changed.

These changes increased performance requirements and improved identification labels. As a result, aftermarket converters now come closer to the original equipment converters in both performance and longevity.

Catalytic Converter ReplacementTechnicians and vehicle owners do NOT have the option of replacing original equipment catalytic converters without first meeting the requirements of the CARB Installers Checklist for New Aftermarket Catalytic Converters, as applicable-

1.The vehicle model is specifically included in the application list for the catalytic converter model I intend to install, and the converter model is approved for use in California.

2.I have verified that the vehicle manufacturer’s warranty for the stock catalytic converter has expired. Warranties will range from a minimum 7 years/70,000 miles to 15 years/150,000 miles.

3.I have confirmed the need for a replacement catalytic converter. If the stock converter is still installed, a diagnosis that it is malfunctioning is required.

Catalytic Converter Replacement 4. The replacement converter will be installed in the same location as the

stock converter (the front face location will be within three inches compared to the stock design).

5. All oxygen sensors will remain installed in their stock location(s).

6. The catalytic converter will be installed on a “one for one basis (only one OEM converter is being replaced by the converter to be installed). Decreasing or increasing the number of catalytic converters (compared to the stock configuration) is prohibited.

7. Warranty Card- I have: (a) Filled out the warranty card (b) Obtained the customer’s signature an the card(c) Attached the card to the original repair order(d) Returned a copy of the warranty card to the catalytic converter

manufacturer

8. I have filed and will maintain a copy of all documentation for a period of at least four years from the date of installation.

Catalytic Converter Replacement

Installers shall keep documentation regarding the installation of the new catalytic converter including all of the above information. This documentation shall be made available to CARB or it’s representative as provided for in title 13, section 222(b)(8). All such records shall be maintained for four years from the date of sale of the catalytic converter.

What Can Damage A New Catalyst?

Quality catalytic converters can perform well for hundreds of thousands of miles

•Anything that significantly increases the amount of HC and/or CO that is oxidized in the converter will increase the operating temperature of the catalyst

•Failing to use manufacturer approved engine oil

•Coolant seeping into the combustion chamber or exhaust

What Can Damage A New Catalyst?

If any of the following conditions exist, the customer (or referring shop) should be notified that the engine might have existing faults that could damage the new converter:

•CO in excess of 2.0% (pre-catalyst)•HC in excess of 400 ppm (pre-catalyst)•Indications of high oil consumption•Indications of combustion/coolant leaks•Indications of O2 sensor faults•Indications of modifications or poor maintenance

Pre OBDII Catalytic Converter Testing

Catalytic Converter Cranking Test

There is typically no CO2 present in the atmosphere. CO2 is a product of combustion. Therefore any carbon dioxide emissions measured during typical starter draw test, with ignition disabled must be created in the catalytic converter. A good catalytic converter should be capable of converting the Hydrocarbon fuel (HC) that is pumped through the engine during the starter test to 13% carbon dioxide. In order to create 13% CO2 during a starter draw test the following must occur: •The catalytic converter must be completely warmed up.•Fuel delivery must be functioning normally. *The CO2 is being created by converting the fuel that is being pumped through the engine.•Ignition must be completely disabled.


THE TEST: 1. Start the engine and drive the car to insure that it is warmed up completely. 2. Run the engine at 2000 rpm to insure that the catalytic converter is hot. 3. Turn off the ignition or hit the analyzer kill switch. 4. IMMEDIATELY after the engine stops, disable the ignition (ground the coil secondary or disconnect the coil primary) and crank the engine over while watching the CO2 levels on the exhaust analyzer. NOTE: The fuel system must remain functional! Do not disable rpm sensor or engage clear flood mode! Disable the ignition system only! Do not allow the converter to cool down!


5. The CO2 level should reach and maintain 13% in about 10 seconds. If the CO2 level does not reach at least 13%, or the CO2 level only spikes to 13%, the catalytic converter is weak. If the CO2 level is below 13% make sure that there is sufficient HC and O2 to make the CO2 from. If the CO2 level drops below 1% or HC drops below 500 ppm the test will not be valid. *This test is difficult to perform on many DIS cars since the ignition is not easily disabled.Use the snap throttle test on such cars.

Shop Practice

Catalytic Converter Snap Throttle Test

When the engine is running at a stoichiometric 14.7:1 fuel mixture with no air injection there is very little oxygen in the exhaust. Cars equipped with carburetors will have higher normal levels of oxygen due to poorer fuel atomization and vaporization. During a snap throttle test, CO will increase due to a suddenly rich mixture on acceleration. CO will continue to increase until the O2 level begins to rise. During this snap acceleration all excess oxygen will be used up by the catalytic converter to convert CO to CO2. As the O2 level rises O2 will be used up by the catalytic converter to convert CO to CO2 and the CO level will begin to drop as O2 rises. A good catalytic converter will therefore prevent the O2 level from exceeding 1.2% until the CO level begins to drop.


THE TEST:

1. Drive the car until the engine and catalytic converter are fully warmed up. 2. Disable the air injection system. 3. Run the engine at 2000 rpm and wait for stable exhaust readings with O2 level no higher than 0.5%. Propane enrichment may be used to reduce O2 level to 0.5%. 4. Snap and release the throttle. 5. Watch the CO emissions climb and note the oxygen level at the instant the CO level peaks. Oxygen level at the instant that CO level peaks should not exceed 1.2%.


THE TEST:

Note: It is normal for Oxygen level to rise after CO has peaked.

If the O2 level exceeds 1.2% before the CO level peaks the catalytic converter is weak.

This test works best on cars that have sequential fuel injection and DIS. The cranking catalytic converter test tends to be difficult to perform on these same cars.

Shop Practice

Catalytic Converter Invasive Test

Catalytic converter efficiency can be determined by sampling the exhaust gas before and after the catalytic converter. Kits are available from Thexton (No. 389), OTC and others to tap through single wall exhaust pipes. Other pre-CAT sampling locations may include the EGR port, EGO port and air injection ports. (EGO is not recommended). Record both the before cat and tailpipe exhaust gas with the engine well tuned, preconditioned, no exhaust leaks and no air injection. Fuel mixture may have to be manipulated and/or misfires induced to create the proper oxygen level for proper evaluation.


(HC in) - (HC out)----------------------- x 100 = CAT HC efficiency(HC in)

HC oxidation efficiency should be 90% when O2 in exceeds 1% and O2 out exceeds 0.5% You may need to induce a misfire to create the proper O2 levels.

(CO in) - (CO out)----------------------- x 100 = CAT CO efficiency(CO in)

CO oxidation efficiency should be 90% when O2 in exceeds 1% and O2 out exceeds 0.5%


(NOx in) - (NOx out)------------------------ x 100 = CAT NOx efficiency(NOx in)

NOx reduction efficiency should be 90% when O2 in is less than 0.5%. This test may require loaded mode testing and/or disabling EGR. It may also be necessary to artificially enrich the air-fuel mixture to reduce O2 content below 0.5%.


NOTE: EPA certifications only require catalysts to oxidize CO & HC at 70% efficiency, and to reduce NOx at 60% efficiency. This may not be sufficient to allow some cars to pass ASM tests. Some cars may require 90% efficiency in NOx reduction. Others may be fine with less than 50%.

The oxidation and reduction efficiency of good catalysts vary due to oxygen levels in the exhaust system during normal running conditions of those cars. 2-way catalysts operating with high oxygen levels in the feed-gas should meet the above standards for CO and HC oxidation. All 3-way catalysts operating with low oxygen levels in the feed-gas should meet the above standards for CO & HC oxidation and NOx reduction.

Shop Practice

Catalytic Converter Light Off Test

This test must be performed with the engine cold.

Start the cold engine and monitor exhaust gas at 2500 rpm during warm up.

Exhaust emission readings should be relatively stable except during the following three events: 1. Initial start up & stabilization.2. Initialization of closed loop.3. Catalytic converter “light-off”. This can be graphed or “traced” so that the readings before and after converter light off can be compared. Use the same formula shown in the “Invasive Test”.

Shop Practice

Catalytic Converter Misfire TestWhen a misfire occurs the catalytic converter releases a tremendous amount of heat as it oxidizes the unburned HC into H2O and CO2. The increased temperature that this causes increases the Catalyst efficiency. This reaction allows us to test the catalyst by inducing a misfire. THE TEST: 1. Allow the car to run for several minutes at 2500 rpm after it is properly warmed up. 2. Disable one spark plug. Do NOT allow the engine or exhaust system to cool down as you do this. It is permissible to turn the engine off while disabling the spark plug, but this must be done and the engine restarted within three minutes. Some engine analyzers will allow you to kill an individual cylinder without turning the engine off.

Catalytic Converter Misfire Test

3. As you induce the misfire, the HC will increase dramatically for several seconds. Then, as the catalyst heats up, the HC level should drop off significantly. Record the Peak HC level and the level that HC drops to as it gets hot. A good catalytic converter will be able to reduce the HC emissions to about 50% or less of the peak HC emissions in just a few seconds. This test must be performed with caution. Do NOT perform this test for extended periods or under a load. A catalytic converter can overheat to the point of melt-down in as little as 12 seconds if multiple spark plugs are disabled while under load. Do not disable multiple cylinders and do not perform the test under loaded conditions.

Shop Practice

Catalytic Converter Temperature and 4-Gas Test

Completely warm up the engine and exhaust system. Run the following test using a 4 or 5 gas analyzer and an infrared temperature sensing gun.

The accuracy of infrared temperature sensing varies according to the "emissivity" of the surface being sensed. Sometimes it is helpful to paint the surfaces with a quick drying flat black paint before testing. Painting is recommended if the two surfaces have different surface finishes.

Is there more than

0.3% oxygen?

Is there more than 0.4% CO?

Is there less than

13% CO2?

Is there more than 400 ppm

HC?

Is there more than 2.0% CO?

Is there a 200 degree

temperature gain in the CAT?

Replace the Catalyst

Is there more than 100 ppm

HC?

YES

YES

NO

NO

NO

NO

NO

NO

NO

YES

YES

YES

YES

YES

The test will not be accurate. There is not enough oxygen for the CAT to do it’s job.

There is not enough fuel present for the CAT to oxidize.

Repair engine or exhaust system and/or disable the air injection system.

Repair engine systems and retest.



Shop Practice

OBDII Catalytic Converter Testing

OBDII Catalytic Converter

A properly operating catalytic converter uses oxygen to oxidize HC and CO into CO2 and O2. The process changes the oxygen level in the exhaust. Under tightly controlled conditions, the PCM will initiate a pattern of fuel control commands and monitor the oxygen sensor response. In order to pass the monitor test the oxygen sensor response must fall within a pre-determined pattern. The pattern is different for each car but the rear oxygen sensor is often compared to the front oxygen sensor to identify changes that the catalytic converter causes in exhaust oxygen content.

Catalytic Converter OBDII Monitor

The OBDII monitor test is typically run automatically on every trip in which the required enable criteria are met. The enable criteria are different on each vehicle. Details of the enable criteria and the drive cycle required to meet those criteria can be found in published service manuals. As mentioned elsewhere in this document, many vehicles that use “exponentially weighted moving averages” as part of the OBDII catalyst monitoring have reduced accuracy immediately after the memory has been cleared. Under these temporary conditions, false fails and false passes are more likely to occur. With this possible exception, OBDII monitors are very accurate. If in doubt, clear codes and retest.

OBDII Catalytic Converter Test Check List

• Confirmation of baseline gas data

• Confirmation of proper engine mechanical operation

• Confirmation of proper ignition system operation

• Confirmation of proper fuel system operation

• Check for Closed Loop Fuel Control


• Check data stream for fuel trim

• Check readiness monitors

• Check for pending codes

• Check for unrelated codes

• Check Exhaust system for leaks Visual Audible Pressure TestSmoke Test the Exhaust System for Leaks


• Secondary Oxygen Sensor TestingActivity

Graphing MeterVolt MeterScan Tool

• Locating SpecificationsManufacturer DocumentationOther service information providersRelated fault code flow chartsMode 6 data parameters

Scenario #1

On an OBDII equipped vehicle

All test results are ok to this point, but NOx is still too high

What test(s) should be performed?

Invasive Test with calculationsWhat is the expected Oxygen Sensor results? Why?

Light-Off Test with calculationsWhat is the expected Oxygen Sensor results? Why?

Shop Practice

THANK YOUNorthern Group, Catalytic Converter Testing

Christine VinsonDennis ShortinoJustin BunchKevin McCartneyKurt ShadboltLarry WilliamsMichael SherburneRay Ortiz

Southern Group, OBD II

Jay HartleyJonathan SummersJose VallejoMark EllisonMichael GaribaySteven Tomory

BAR wishes to thank the following individuals for their contributions

smog check

Documents

asm inspection

timing inspection

inspection qualitywhat

vehicle test restrictions

failing vehicle

dynoverify vehicle

dryverify vehicle

required inspection