Connecticut Emissions Test
Any car 25 years and older
is exempt from the Connecticut Emissions Test, but I was
curious as to the impact of converting the car to
Throttle Body Injection. Does having all these "modern"
components make the car cleaner or wouldn't it matter
seeing as there's no catalytic converter. So I stopped
by one of only two test stations in town to find out. It
was quite an interesting experience for both the garage
and me. The car gets backed on to rollers and the front
wheels chocked. Then the proctologist visits the tail
pipe with his magic wand and inserts it. Next up was
plugging into a 12V outlet which luckily I have. Finally
it was time to enter the car info into the computer.
VIN# CF38503U gets entered and ............BURP.....
invalid number! No problemo...........just switch over
to the manual mode and enter it again. Now a 1975
Triumph TR6...........BURP.........why are you testing a
33 year old exempt car?!? Invalid, invalid. Not allowed.
Now what? Ah yes.......training mode.....and this takes
the local PC offline from the big mother State computer
in the sky. Try again.....1975 Triumph
TR6.....BURP......no emissions data available for 1975.
OK.......so now I'm driving a 1984 Triumph TR6 which
isn't a valid car but it's good enough for testing
training mode. Go figure.....but here's the
scenario......we have a 1975 car/engine being tested
against 1984 standards.
Sorry about the
picture quality but I took it with my cell
OK.....if you've read this
far you must really be curious as to how this all turned
out....... well, 2 out of 3 ain't bad. I easily passed
the HC and NOx tests but failed the CO test. The chart
below shows the Upper Limit and my results.
1975 Standards -
1984 Standards -
1975 TBI TR6
So while I failed the CO
test as based on 1984 standards, it did pass relative to the 1975 standards.
And while I passed the other two based on 1984
standards, one set of standards is
in grams/mile while the newer one is in parts/million.
Is it possible to convert one to the other? In talking
to Rick Patton, I could do another data logging drive
and submit the log file for analysis but the car runs
great as is, gets good fuel mileage and...........I
don't have to be tested in Connecticut!
CO too high = Car runs rich, burns too much gas.
Bad carburetor adjustment, float too high, carburetor flooding, sticking
secondary throttle, leaking fuel injector, leaking fuel pressure regulator,
feedback system malfunction (oxygen sensor, coolant sensor, throttle position
sensor), emissions vapor system malfunction (purge valve, canister clogged) Be
aware that NOX will RISE after you fix a CO problem. This must be checked after
a successful CO repair.
HC too high = unburned fuel in exhaust; car runs very rich or very lean.
This is the trickiest condition because there are different causes. If the car
is running rich (high CO), the HC can be high also. If the CO is very low and HC
is high then the vehicle has a lean misfire.
If The CO is high, fix that problem first. If CO is low and HC is high look for
engine skipping, misfire due to vacuum leaks, ignition timing set too advanced,
ignition misfire problem (plugs, wires, cap), low fuel pressure, carburetor
adjusted too lean. If you canít find a reason for the high HC then perform
balance test then compression test to check for engine mechanical problem.
NOX too high = NOX forms in normal combustion. NOX too high indicates
high combustion chamber temperatures or malfunctioning post-combustion emission
CO and HC must be normal before attempting to repair NOX failure. Anything that
can create high combustion chamber temperatures will make NOX reading high.
Engine overheating, air cleaner hot air door stuck closed, egr vale not
functioning, clogged egr valve passage, lean fuel mixture, ignition timing set
too high. The two main systems that reduce NOX on a car are the egr system and
catalytic converter. If your car is pinging, the NOX will be too high. Pinging
is a symptom of high combustion chamber temperature. If all the test readings
are just a little too high (slightly high CO, HC, and NOX) it is likely the
catalytic converter is damaged or empty. If your converter is supposed to have
air injection and it is disabled, the converter will not function properly.
History of Reducing Tailpipe Emissions
1970-1975: The First
Standards In 1970, Congress passes the Clean Air
Act, which called for the first tailpipe emissions
standards. The pollutants controlled are carbon monoxide
(CO), volatile organic compounds (VOC), and oxides of
nitrogen (NOx). The new standards go into effect in 1975
with a NOx standard for cars and light-duty trucks of
3.1 grams per mile (gpm).
Standards for the First Time In 1977, Congress
amends the Clean Air Act and tightens emission standards
again in two steps. First, between 1977 and 1979, the
NOx standard becomes 2.0 gpm for cars. Then in 1981, the
NOx standard for cars is reduced to 1.0 gpm. Effective
in 1979, pursuant to the Clean Air Act requirements, EPA
tightens standards for light-duty trucks to 2.3 gpm.
Effective in 1988, EPA then sets the first tailpipe
standards for heavier trucks at 1.7 gpm and revises the
standard for lighter trucks to 1.2 gpm.
1990-1994: Tier 1
In 1990, Congress again amends the Clean Air Act,
further tightening emission standards. The NOx standard
is set at 0.6 gpm for cars, effective in 1994. The new
standard called "Tier 1"is a 40 percent reduction from
the 1981 standard. For trucks, the new standard ranges
from 0.6 to 1.53 gpm, depending on the weight of the
The Clean Air Act
Amendments of 1990 also require EPA to assess the air
quality need, cost effectiveness, and feasibility of
tighter emission standards for the 2004 model year and
Agreement For Cleaner Cars In 1998, the Clinton
Administration with the auto industry and the Northeast
states strike an innovative, voluntary agreement to put
cleaner cars on the road before they could be mandated
under the Clean Air Act. The new cars are called
National Low Emission Vehicles (NLEV). The first NLEV
cars under the agreement reach consumers in New England
in 1999 and will reach the rest of the country in 2001.
NLEV cars operate with a NOx standard of 0.3 gpm, a 50
percent reduction from Tier 1 standards. The NLEV
agreement also calls for a 0.5 gpm NOx standard for
lighter trucks only, a 17 percent reduction from Tier 1
requirements for these vehicles.
In 1998, as required by
the Clean Air Act Amendments of 1990, EPA issues the
Tier 2 Report to Congress. The report contains strong
evidence of the need, cost-effectiveness and feasibility
for tighter tailpipe emission standards in the future
beginning in 2004. Three main factors support EPA's
1) currently vehicles
make up 30 percent of smog-forming emissions
nationally, and because the number of miles driven
is increasing (up 127 percent since 1970) they will
continue to be a significant contributor to
In 1998, EPA also determines
that sulfur reductions in gasoline are needed to enable
the full performance of low emission-control devices.
2) larger vehicles
like SUVs, that currently do not meet the same
standards as cars, pollute 3-5 times as much and
make up 50 percent of the vehicles sold today; and
3) the technology to
meet tighter standards is available and
1999: Tier 2 In
1999, EPA proposes Tier 2 tailpipe emissions standards
beginning in 2004the first time both cars and light-duty
trucks are subject to the same national pollution
control system. The new standard is 0.07 gpm for NOx, a
77-86 percent reduction for cars and a 92-95 percent
reduction for trucks beyond the NLEV agreement. EPA also
proposes a reduction in average sulfur levels to 30
parts per million (ppm) (maximum of 80 ppm) to achieve
the full performance of vehicle emission control
As part of these new
standards, EPA has included several measures to ensure
maximum flexibility and cost-effectiveness. These
- allowing averaging to
meet both the car emission and gasoline sulfur
- allowing extra time
for larger vehicles between 6000 and 8500 pounds and
smaller refiners to meet their respective standards;
- allowing for a
market-based credit trading-and-banking system for
both industries to reward those who lead the way in
History of Reducing Tailpipe Emissions