Air Care News
August 1996
Repair the problem, not the symptoms
by Chris Chesney
After sixteen months of assisting technicians in the diagnosis and
repair of I/M 240 failures, I am amazed that many try to use an idle test to determine if a
vehicle will pass an enhanced emissions test. Many wonder why the vehicle passes the old test yet
fails the new test. I hear about cars and trucks that fail the old test and pass the new one.
The reason is simple: There is no similarity between
the old BAR 84/90 test and the new I/M 240 test. The idle test samples a tiny portion of the
exhaust stream with no load applied to the vehicle. The I/M 240 samples all
of the exhaust under load while the wheels are spinning.
Modern computerized cars and trucks operate under a different
set of rules when driven down the road from the way that they do at idle. If we only idled
to work, the old test would suffice. We don't, so the old test falls short.
Since today's cars and trucks operate differently while driving
down the road from the way they do at idle, we need a test that samples emissions under similar
operating conditions. The I/M 240 does that. The problem for technicians lies in diagnosing and
repairing I/M 240 failures, particularly those that would not have resulted in a failure under the
old system.
A first step for technicians having difficulty adjusting to the new
test is to throw out the old one as a gauge. The old diagnostic strategies and repairs will not work.
Technicians must understand how a vehicle's computer-controlled
fuel system thinks and functions. It will remain difficult to repair I/M 240 failures otherwise.
You do not need a lot of expensive equipment to repair a problem vehicle, just a thorough understanding
of the new set of rules that apply. If a vehicle is operating as designed, it will easily pass the
enhanced test.
Some technicians have had a fair amount of success repairing I/M
240 failures successfully without additional knowledge and training. However, if and when standards
are tightened, these technicians will not be prepared. What now results in a passing test may next
year be a failing one.
Please don't wait until it is too late. There is a difference
in the test and in the approach needed to repair failures successfully. The ramifications of the I/M
240 are no different to a repair technician than the introduction of disc brakes: it requires different
knowledge and techniques. Repair technicians met the challenge then. I believe they will now.
First, however, we must accept that there is a difference. Let's
move forward to solve the problem. We must repair the entire system rather than the symptoms.
Chris Chesney is the owner of Diagnostic
Technician Education Consultants (DTEC), 5497 S. Danube Way, Aurora, CO 80015. He can be reached at
720-870-6761 or via email atchesneydtec@cs.com. Chris has
trained hundreds of technicians in I/M 240 diagnosis and repair.
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New law allows dealer emissions vouchers
At the end of the 1996 legislative session, the Colorado
General Assembly passed HB96-1377. It allows any licensed new or used motor vehicle dealer who sells
a motor vehicle to any individual residing within the Denver metro enhanced emissions program area
to provide an emissions voucher rather than having the emissions tested prior to the sale.
The emissions voucher gives the buyer three business days to
have the vehicle tested for compliance with emissions test requirements. If the vehicle fails the
emissions test, the buyer can return the vehicle to the selling dealer. The dealer then has three
options: repurchase the vehicle at the purchase price, repair the vehicle to pass emissions testing
(at the dealer's expense), or have an independent repair facility repair the vehicle to pass emissions
testing (at the dealer's expense).
Repair technicians will be asked to repair vehicles sold with an
emissions test voucher. The new law requires that the vehicle be repaired sufficiently to comply with
emissions test requirements in the enhanced program area.
Many smaller dealers may utilize outside repair facilities to
provide emissions repairs for failing vehicles. Be advised: the selling dealer is liable for payment
of repair costs for emissions failures on any vehicle sold with an emissions voucher. The buyer is not
liable for payment of such repairs.
If you have any questions concerning this new law, call the
Colorado Department of Revenue Motor Vehicle Emissions Program at 205-5603. The CDOR will be writing
regulations to implement and oversee this new emissions law.
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In support of the vehicle emissions inspection programs
(gasoline and diesel), the State of Colorado operates five Emissions Technical Centers along Colorado's
Front Range. These facilities are located inDenver, Aurora, Broomfield, Fort Collins and Colorado
Springs.
Customers of the state Emissions Technical Centers are motorists,
repair industry professionals, motor vehicle dealers and any person involved with or affected by the
vehicle emissions inspection programs. Automotive repair technician training, testing and certification
are also conducted through the Emissions Technical Centers, and program and vehicle technical information
are regularly provided.
Each center provides a variety of vehicle technical information,
including:
emissions control system verification (identifying needed emissions equipment)
engine/chassis model year evaluation
kit car/homebuilt evaluation
non-U.S. certified vehicle verification (gray market vehicles)
GVWR (certification, class) verification
fuel system change evaluation
fuel inlet restrictor failure
visible smoke verification
multiple failure diagnosis
test rejections (safety concerns, body clearance, underpowered, etc.)
diagnostic waivers
technical assistance to the Colorado Department of Revenue
Each of these areas will be the subject of more detailed articles
in future issues of Air Care News.
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not just spinning
wheels
by Christopher Dann
Josh Lowenstein at Best Tune Auto Service ain't just blowin' smoke
when it comes to living up to the shop's name. He has the diagnostic equipment to prove it.
Lowenstein recently invested in a chassis dynamometer for himself
and his technicians to improve an already impressive record of diagnosis and repair of I/M 240
emissions-related failures.
He won't divulge how much he spent on the dyno, but he said that
"it's a reasonable investment on account of the fact that we do a lot of jetting work and
work on the Holly Projection System, which a lot of shops won't touch."
Lowenstein, in business for himself for nearly four years, credits
driveability and emissions-related work for about 75 percent of his business.
"Maybe a little more since the I/M 240," he said.
"The work is more specialized now."
That accounts for the dyno in a bay at his shop at the corner of
Federal and Hampden in Englewood. It is a good bridge between the old four-gas analyzer his technicians
still use on occasion and the state-of-the-art dynos that perform the I/M 240 test at 15 Air Care
Colorado Emissions Testing Centers throughout the metro area.
"The dyno is a great diagnostic tool," Lowenstein
said. "As we run more and more cars on it, we'll achieve a standard and closer
relationship with the I/M 240."
Lowenstein and his techs had a lot of success in diagnosing and
repairing I/M 240-related failures. His shop's Repair Effectiveness Index was a solid 81.4 in the May
edition of the handbook, despite repairing more vehicles for reporting to the state
accounting system (126) than nearly any other shop in the Denver-metro area.
He and technicians Bill Fischer and Steve Sherman have
considerable I/M 240 training -- so much so that other shops in the area send business their way.
"We've had a lot of success with common failures other people
haven't had a whole lot of luck fixing," Lowenstein said. "We don't see a lot of the
older cars (81-and-older vehicles that aren't required to have an I/M 240 test). Shops less specialized
than ours take good care of the older cars."
Lowenstein already has examples of how the dyno has helped him
cut through a difficult diagnosis to make a necessary repair.
"It sure takes a lot of the guesswork out of it," he said.
He hopes more and more shops and technicians will realize that
the old four-gas analyzer is not the way to go when repairing a failed vehicle for a successful I/M 240
test.
"I still hear all the time, 'But it blew zeros on the
four-gas and blows dirt at Envirotest,'" he said. "The difference between the old analyzer and
the I/M 240 is apples and oranges. My dyno makes it fruit salad. It's not all clear, but it mixes it
together a lot better."
Christopher Dann is the public information officer for
the Air Pollution Control Division, Colorado Department of Public Health & Environment.
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tips
by Jerry Lyons
I recently encountered a Ford Taurus that had a problem giving
accurate oxygen sensor signals to the PCM. The oxygen sensor voltage always seemed to be low -- even
when the engine was enriched with propane.
A new sensor also seemed to have the same problem, leading me to
think that the problem was with the wiring harness. However, a talk with Jim Speck at
Lincoln-Mercury Mazda of Boulder resulted in a new direction.
Many Ford Tauruses have experienced similar problems with leaky
power steering systems. The power steering fluid leaks down onto the oxygen sensor and into its
connection in the vehicle wire harness.
On a three-wire heated oxygen sensor, one of the wires
(heater ground) is attached directly to ground. The power steering fluid acts as a conductor and routes
the oxygen sensor voltage to the ground. This causes low oxygen sensor voltages, even when a new
sensor is installed and the engine is artificially enriched with propane.
If you discover this problem, try to seal the connection should a
power steering system leak recur. We used some large shrink tubing and extended it about two inches on
either side of the connection. Obviously, the power steering leak should be repaired as well.
Be aware of the power steering fluid or any other material that
could get into the loose metal end of the oxygen sensor itself. This loose-fitting end is supposed
to remain open to allow ambient air into the outside of the sensor (actually, inside the sensor without
being exposed to exhaust) so the sensor can distinguish the difference in oxygen from the ambient air
relative to the engine exhaust.
Jerry Lyons is an air/environmental systems
technician with the Colorado Department of Public Health & Environment, Air Pollution Control
Division.
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