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11 Exhaust

11-2 Visible exhaust smoke

Reasons for rejection

1. A vehicle with the engine at normal operating temperature (Note 1), other than a vehicle in Reason for rejection 2, emits clearly visible smoke (Technical bulletin 8) from the exhaust tail pipe (Note 2):

a) for a continuous period of five seconds when the engine is idling, or

b) as the engine is being rapidly accelerated to approximately 2500 rpm or approximately half the maximum engine speed (whichever is lower) (Note 3).

2. A vehicle fitted with an engine that is designed in a way that the vehicle cannot reasonably comply with Reason for rejection 1 emits smoke that is noticeably and significantly more visible than it would have been when the vehicle was manufactured and supplied with the recommended fuel (Note 4).

Note 1

Test procedure:

a) Carry out the idling and acceleration tests in Reason for rejection 1. A vehicle that passes both tests with the engine below normal operating temperature is deemed to have passed with the engine at normal operating temperature.

b) If the vehicle has failed either test, ensure the engine is at normal operating temperature. Then purge the system by increasing the engine speed to 2500 rpm (or half the maximum engine speed if this is lower) and holding it there for about five seconds. Repeat the idling and acceleration tests in Reason for rejection 1.

Note 2

Visible emissions caused by the condensation of water vapour do not count as smoke.

Note 3

During the acceleration test, a diesel-powered vehicle may emit a moderate amount of smoke if this is caused by turbo lag.

Note 4

The vehicle inspector may need to take into account information from the vehicle manufacturer or their representative or other appropriate expert, eg about older or unusual vehicles.

Summary of legislation

Applicable legislation
Performance

1. A self-propelled vehicle must not emit clearly visible smoke (Note 2) when the engine is running at its normal operating temperature, under either of the following conditions:

a) for a continuous period of five seconds when the engine is idling, or

b) as the engine is being accelerated rapidly to approximately 2500 revolutions per minute or approximately half the maximum engine speed (whichever is lower).

2. Requirement 1 above does not apply if the driver of the vehicle produces documentation that proves that the engine is original equipment for the vehicle and the engine’s design does not allow the vehicle to reasonably comply.