Air Care News
April 1999
Replacements
required for more catalytic converters
by Gary Cagle, Ph.D.
As the I/M program matures
and emissions standards tighten, more catalytic converters are being tested and replaced.
Contrary to popular belief, converters do degrade as vehicles add miles. Some of the
reasons for degradation include:
1. Small active
sites in the converter. They flake off and simply blow out the tailpipe with the exhaust
stream. This limits the active surface area within the converter in which catalyst reactions occur.
2. High sulfur content
in the fuel. This has a tendency to coat or cover active sites on converter material, thereby
reducing converter efficiency. Some converters have been shown to reactivate themselves and increase
efficiency when lower sulfur fuels are used.
3. Thermal stress.
Converters live in a hot/cool environment. If cooled too quickly, they can develop thermal
stress cracks. This is similar to dropping an ice cube into a cup of warm water -- the ice will crack.
Thermal stress can be produced by rich air/fuel mixtures or by external sources such as rain or snow.
The converter, like the ice cube, may break up internally and start moving around, and can eventually
plug the exhaust system, or pieces will just blow out through the exhaust system.
A good example of converter degradation can be seen by tracking
a vehicle over its life span. Let's track a 1990 Dodge Daytona 2.5 liter with throttle body injection.
The chart above demonstrates "normal" deterioration of the converter, as well as the
effect of typical engine wear.
The I/M emissions cut points for this vehicle that took effect
Jan. 1, 1999 are 3.0 grams per mile for hydrocarbons (HC), 20.0 grams per mile for carbon monoxide
(CO) and 6.0 grams per mile for oxides of nitrogen (NOx).
When the vehicle is new, the tailpipe
numbers are extremely low. As the vehicle ends its "useful life" warranty
period (5 years or 50,000 miles), notice how close the vehicle is to the maximum new car
certification numbers. As the vehicle continues to age and accumulate more mileage, the efficiency
of the converter is substantially reduced. Important to remember is that the vehicle is not
"broken" and did not fail the tighter I/M 240 emissions limits, even with a well-aged converter.
With proper maintenance, the vehicle stands a good chance of more passing tests.
Gary Cagle is an environmental
protection specialist with the Colorado Department of Public Health and Environment, Air Pollution
Division, Mobile Sources Section.
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February Tech Night
provided a rare opportunity for technicians and shop owners to use their own equipment and
problem vehicles to gather information using actual I/M 240 equipment.
The group of about 40 gathered at Envirotest's Broomfield
station to discuss the new standards changes and the challenges the changes present.
Representatives from the Colorado Department of Public
Health and Environment (CDPHE), Envirotest and Snap-On Tools gave presentations and were available
for follow-up questions and discussion.
Chris Chesney, a Snap-On Tools trainer and owner of Traxx Auto
Services in Englewood, emphasized the importance of following procedure and not skipping steps when
performing emissions repairs. He told the group that the new standards would prove to be very
challenging, pointing out that with the old standards many vehicles that failed the first test, passed
the second with minimal repairs. With the new standards, he said, this will not be the case.
Gary Cagle, CDPHE, Chesney said, is seeing more and more
"marginal failures," referring to vehicles that seem to have no drivability or other obvious
problems, yet still barely fail the I/M 240 test.
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In the last issue of Air Care
News we highlighted the responses of a recent motorist focus group. In this issue we highlight
the responses of the service advisor focus group that was part of the same project.
The group consisted of eight men and one woman employed
by repair facilities listed in the Emissions Repair Guide.
All participants stated that they believe the quality of the
I/M 240 test is high and that it has real value. Further, they feet that emissions tests are an
important factor in the reduction of air pollution.
As with the motorist group, however, no one had a magic bullet
that would convince motorists to perform better maintenance on their vehicles.
Several of the focus group members did have some specific
recommendations for the Air Care Colorado program:
Improve the Emissions Repair Guide. Make it more user-friendly.
Improve the
Vehicle Inspection Report by deleting or moving the "probable cause" section.
Discourage testing station
employees from providing customers with suggestions why the vehicle may have failed.
Hold more training sessions.
Conduct them on weekday evenings.
Get the Air Care News
newsletter out to the entire target audience (all service advisors and technicians).
All of these suggestions have been or are being considered and
some have already been put into place.
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Inoperable vehicles don't need emissions tests
by Tom Myrsiades
Colorado Law requires
licensed car dealers and private individuals to provide a new, valid emissions Certificate
of Compliance at the time of sale or transfer of a vehicle to a new buyer. This
provision in state law protects the purchaser. Prior to 1998, the law prevented legal sale
of vehicles that were not testable and/or inoperable due to major mechanical defects.
However, the law was revised in 1998 to exclude inoperable vehicles.
Under the new law, a
vehicle may be sold without an emissions test or voucher providing the vehicle is
inoperable and the seller has disclosed the vehicle's defects to the buyer with the use of
an official, "Notice of Emissions Non-Compliance" form, (DR2023). The
information listed on this form must include vehicle make, model, year, vehicle
identification number, seller's information, buyer's information, and a description of the
condition that renders the vehicle inoperative under the definitions of an inoperable
vehicle.
This provision is not intended to
waive the seller's responsibility to provide a new emissions test.
Conditions that will not be allowed under the new law
include (but are not limited to) things like a dead battery, no fuel, flat tire, lost ignition keys,
broken head lamps or tail lights, or emissions test failure.
In order to qualify as a legal sale, the vehicle's engine and/or
drive train must have major internal mechanical defects that will not allow the vehicle to be
driven unless major repairs are performed. Form DR2023 must be completely filled out and
signed by both the seller and the purchaser.
For additional information or a copy of the official form, contact
the Motor Vehicle Division Emissions Section, (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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