RiteFlo by acs

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RiteFlo by acs
RiteFlo by acs
OBDII Training Module
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Ground To Cover

• What does a catalytic converter do?
• What is OBDII?
• Why do OBDII converters fail?
• Whats important in replacing them?

Whats All The Fuss About OBDII?
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What Does A Catalytic Converter Do?
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Three Way Converter (TWC)
Harmful Gases Converted
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What Is A Catalytic Converter?

• Ceramic or metal substrate
• Substrate coated with platinum group metals (PGM)
  very expensive
• Platinum, palladium, rhodium
• Insulation wrapped around substrate
• Enclosed in stainless steel container

Located Between Engine And Muffler
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How Does It Work?

• Exhaust gases pass through coated substrate
• Catalyst on substrate reacts with harmful gases
• Harmful gases converted to CO2, H2O, N2

Toxic Gases Converted To Common Gases
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Combustion Process

• Perfect combustion
• Gasoline O2 ? CO2 H2O
• Harmful side-effect gases
• CO carbon monoxide
• HC unburnt fuel
• NO and NO2 (NOX) nitrogen oxides

Imperfect Combustion Products Result
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Why Are They Harmful?

• CO
• Poisonous, colorless, odorless
• HC
• Contribute to ground-level ozone, smog
• May cause cancer
• NOX
• Contributes to smog, acid rain
• Can cause irritation to lungs

Health Problems May Result
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Chemical Reactions

• Oxidation reaction
• CO O2 ? CO2
• Gasoline O2 ? CO2 H2O
• Reduction reaction
• NOX ? O2 N2

Harmful Gases Converted By Catalyst
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What is OBDII?
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Engine Control For Emissions
Other Sensors
Engine Control Module (ECM)
OBDII Diagnostics
MIL
Fuel Injectors
Engine
Catalytic Converter
Oxygen Sensors
Engine Control And Emissions Monitoring
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How Does It Work?

• 1996 and newer cars (some 94-95)
• Electronic fuel and ignition control
• O2 sensors before, after converter
• ECM adjusts air/fuel ratio, ignition
• OBDII monitors for emissions

Controls To Reduce Emissions
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Oxygen Sensors

• One ahead of converter signals ECM to optimize
  air/fuel ratio
• One after converter measures emissions reduction
  performance
• MIL turns on if ECM cant achieve

Sensor Feedback For Engine/Converter
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How Do I Tell If OBDII?
Vehicle Emission Nameplate Under Hood
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Why Do OBDII Converters Fail?
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Rich Air/Fuel Ratio

• Converter overheats and melts
• Causes
• Improper fuel mixture
• Improper timing
• Faulty spark plugs or wires
• Defective fuel injector
• Faulty oxygen sensor

Engine Tuning Vital To Converter Life
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Carbon Deposits

• Carbon on substrate fouls function
• Causes
• Oil or antifreeze in exhaust stream
• Look for worn piston rings, valve seals or failed
  gaskets

Maintenance Problems Foul Converter
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Other Causes

• Leaded fuels
• Will poison catalyst and render it useless
• Catalyst breakage
• Look for dents or broken hangers

Never Use Leaded Fuels
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Failed Oxygen Sensors

• Same contaminants as for converters will impair
  function
• Deposit on probe will sense lean, ECM enriches,
  problem gets worse

Check Sensor Before Replacing Converter
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Whats Important In Replacing Them?
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What EPA Regulations Say

• Regulator specifies performance not design
• good enough that the catalyst monitor will not
  detect a problem for the required 25,000 mile
  performance period (EPA letter Aug. 2, 2000)
• Inadequate catalyst may initially turn MIL off
  but have it come on again after curing

OBDII Compliant Not The Whole Story
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Fix The Root Cause

• OEM converters should last life of car
• Address the maintenance issue first
• Check the oxygen sensors
• Replacement converter must have adequate PGM
  loading

Dont Compromise And Risk A Comeback
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Replacing The Converter

• Use scan tool and address all faults
• Replace each failed converter
• Maintain oxygen sensor locations
• Installation must be leak free
• Reset fault codes and road test vehicle

Use Converter Recommended For Vehicle