This
inspection applies to:
All spark
ignition engine vehicles with four or more wheels, except quadricycles and electric/combustion
engine (Hybrid) vehicles. Contained within this section are flowcharts. Carefully
use these flowcharts to accurately establish which type of emission test is applicable
to the vehicle being tested.
Vehicles fitted with modified engines:
If an engine has been modified in any way, it still has to meet the exhaust
emission requirements according to the age of the vehicle.
Personal Imports:
The vehicle will be tested according to its age from first use. The only exemption
to this is if the vehicle owner can present to the tester at time of test a letter
from the vehicle manufacturer stating that the particular engine as originally
installed could not meet the equivalent British emission standards.
If this is the case, then test to the next lower emission standard. e.g. A 1995
car first used in Africa has a letter from the engine manufacturer stating that
the particular engine (engine number to be stated) cannot meet Catalyst emission
limits, then use the pre cat limits of CO 3.5%, HC 1200ppm.
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Engine speed and temperature
When checking exhaust emissions, the engine must be at its normal idle speed
and normal operating temperature. Engine speeds and temperature can be assessed
either subjectively or by reference to manufacturer’s or other reliable data.
Gas analyser probe It is important to ensure that the gas analyser probe is inserted
as fully as possible into the exhaust pipe and is secure. Recording emissions
test results Record the results of the tests via the VTS Device.
(See Introduction paragraph 3 at the beginning of this Inspection Manual). Early
catalyst vehicles The flowcharts and notes must be carefully followed. If a vehicle
is fitted with a catalyst it does not necessarily mean a ‘CAT’ test is required.
Working environment To prevent the build up of fumes, the test should be carried
out in a well ventilated area.
Exhaust extraction systems Exhaust extraction systems that connect directly onto
the tailpipe must not be used during the emissions test. Remote systems are acceptable,
but they must not be placed closer than 250mm to the tailpipe. Note that the availability
of an extraction system is not a condition of appointment. |
Vehicles fitted
with a different engine:
Test according
to which is older, engine or vehicle. e.g. A 1995 car fitted with a 1991 engine
(of whatever make), test to 1991 standards for emission purposes.
Note: The onus is on the vehicle presenter to prove engine age.
The following notes should be used in conjunction with the flowcharts on the following
pages.
(1) Two stroke engines do not require an emissions test unless they are subject
to the catalyst test.
(2) <= less than or equal to
(3) Advice on establishing whether the design gross weight of a large car exceeds
2500kg
(i) it may be shown on the manufacturers VIN plate (example shown in Section 3.9)
(ii) it may be listed only in Section 2 of the current emissions data book
(iii) refer to any readily available data, e.g. handbook or data book
(iv) if still unsure, assume it to be over 2500kg DGW.
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A. All vehicles
Raise the engine speed to around 2500 rpm or half the maximum engine speed
if this is lower. Hold this speed steady for 20 seconds
a. assess the engine idle speed
b. assess the smoke emitted from the tailpipe at idle
c. rapidly increase the engine speed to around 2500rpm or half maximum engine
speed if this is lower and assess the smoke emitted from the tailpipe. Allow the
engine to return to idle.
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(4) Vehicles, which
have been the subject of specialist conversions, are to be treated, for emissions
purposes, as if they had not been converted, e.g. a motor caravan or ambulance
converted from a goods vehicle is still to be treated as not being a “passenger
car”; an ambulance converted from a “passenger car” or a “passenger car” with
seats added is still to be treated as being a “passenger car”.
A vehicle originally built with 6 or more seats, in addition to the driver, which
has had seats removed is still to be treated as not being a “passenger car”.
(5) The full title of the Department of Transport Emissions book is “In- Service
Exhaust Emission Standards for Road Vehicles”. The latest edition must be used
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1. The engine
a. is idling at a speed clearly above its normal idling speed
b. emits dense blue or clearly visible black smoke for a continuous period of
5 seconds at idle
c. emits excessive dense blue or clearly visible black smoke during acceleration
which would obscure the view of other road users.
Note: Older vehicles, particularly pre-1960, may emit unavoidable smoke due to
their design. Such smoke is not a reason for rejection
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