Air Care News
October 1997
Catalytic converter efficiency testing
How many times have you replaced a catalytic converter out of frustration
during a tough emissions repair? Not having the tools and techniques to determine
whether the converter was bad or not was the real frustration.
Replacement can be a "quick fix" to get a car to pass the next
emissions test, but it is usually a temporary repair that covers up faults upstream.
You can count on at least some of those vehicles coming back for additional repairs.
The industry has been searching a long time for a reliable diagnostic procedure
to see how well a catalytic converter is working. Here are five procedures to help
technicians that can be performed in a repair bay.
Before and After Sampling: Measure carbon monoxide (CO) and hydrocarbon (HC) levels
going into and out of the converter. If levels are lower after exhaust has traveled through
the converter, the converter is okay (drill the headpipe or remove the oxygen sensor before
getting the sample going into the converter).
Temperature Rise: Catalytic converters generate their own heat. Measure inlet and
outlet pipe temperatures. The outlet pipe temperature should be higher by at least 50 degrees.
Use a thermocouple, non-contact infrared thermometer or thermomelt temperature crayons.
Propane Cranking Oxidation: Inject a known amount of propane HC while cranking a
hot engine with the ignition and fuel system disabled to estimate HC and carbon dioxide
(CO2) values at
the tailpipe. Compare these values to predict converter effectiveness.
Fuel Metering Cranking Oxidation: Crank a hot engine with the ignition
disabled and fuel metering enabled to predict CO2
and HC values at the tailpipe.
I/M 240 Test Results: Check fuel control and mass emissions values.
This method was developed by Colorado State University's National Center for Vehicle
Emissions Control.
Of course, professional training that includes mass vs. concentration,
load vs. idle, catalyst preconditioning, overheating and safety is your best bet to
increase your knowledge of diagnosing catalytic converter effectiveness.
There are a lot of converters out there that need to be replaced. Get some
training on catalytic converter effectiveness so that you replace only those that
really need it. Improve your productivity!
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It is important that technicians be aware of the following
changes to Air Quality Control Commission Regulation No. 11 which governs the Colorado vehicle
emissions program.
These items have changed and are now in effect:
State-licensed emissions inspection facilities (Envirotest and independent test providers)
will continue to fail vehicles on an initial inspection if fuel inlet restrictors exceed the gauge
tolerance.
Automatic failure of the catalytic converter and O2 sensor is no longer required
on a fuel inlet restrictor failure.
If the catalytic converter and O2 sensor are present, intact and appear operable,
the only required repair is to the fuel inlet restrictor.
Fuel inlet restrictors must be repaired in a secure and permanent manner.
After completion of the repair, the emissions retest may be performed without a lead test from
an Emissions Technical Center.
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Tough penalties for
emissions fraud
by Tom Myrsiades
An article in the July issue of Air Care News gave
examples of illegal emissions tests and fraudulent actions aimed at passing vehicles that otherwise
could not pass either a basic or enhanced emissions test.
As disturbing as these types of fraud are, the Colorado Department of Revenue (CDOR) does not
believe these incidents are widespread. Changing to a more centralized program with fewer test
providers has helped to eliminate much of the fraud.
Tough penalties in Colorado's Criminal code help deter
individuals from attempting these types of fraud.
Under Colorado Criminal Code CRS-18-5-102 and 103, making or
completing a false written instrument for recording is a felony. This applies to falsifying a vehicle
inspection report (the written instrument) for the purpose of registering a vehicle (the recording).
Such an act carries a possible sentence of one to four years in jail and a fine of $100 to $1,000.
Fraud will not be tolerated. Perpetrators will be prosecuted.
We cannot allow a few dishonest individuals to tarnish the program.
The CDOR is interested in learning about any alleged illegal
testing. We will investigate all cases reported to us. If you have any information, questions or
concerns, please contact CDOR at:
Emissions Section
1881 Pierce Street
Room 128
Lakewood, CO 80256
(303) 205-5603
Tom Myrsiades is an emissions compliance
supervisor with the Colorado Department of Revenue, Division of Motor Vehicles, Emissions
Section.
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