California Code of Regulations › Title 13 - Motor Vehicles › Division 2 - Department of the California Highway Patrol › Chapter 4 - Special Equipment › Article 9 - Exhaust System Noise Measurement › Section 1036 - Passenger Cars and Light Trucks and Buses

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
Exhaust systems for motor vehicles, other than motorcycles,
					 with a manufacturer's gross vehicle weight rating of less than 6,000 lb (2,722
					 kg) shall comply with the specified noise limits when tested in accordance with
					 the following specifications:
(a)
				  Measuring Site. The vehicle under test shall be positioned either on outdoor
				  pavement or on a shop floor (but not over a hoist or pit) in a location where
				  the exhaust outlets are near an open shop door. No sound-reflecting surface
				  other than the pavement and the vehicle being measured shall be within 10 ft
				  (3.0 m) of any part of the vehicle.
(b) Microphone Location. The microphone for
				  the sound level meter shall be at the same height as the center of the exhaust
				  outlet. The microphone shall be no closer to the pavement than 8 in. (203 mm)
				  when the exhaust outlet is lower than this height (Figure 1). The microphone
				  shall be positioned with its longitudinal axis parallel to the ground, 20
				  ± 1 in. (508 ± 24 mm) from the nearest edge of the exhaust
				  outlet, and 45 ± 10 deg from the axis of the outlet (Figure 2). For
				  exhaust outlets located under the vehicle body, the microphone shall be located
				  at the specified angle and at least 8 in. (203 mm) from the nearest part of the
				  vehicle. For exhaust outlets that make an angle of 45 deg or less with the
				  longitudinal axis of the vehicle, the microphone shall be outboard of the
				  exhaust axis. For exhaust outlet angles of more than 45 deg, the microphone
				  shall be on the side of the exhaust axis to the rear of the vehicle (Figure 3).
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(c) Engine Operation. The engine shall be at
				  normal running temperature with the transmission in neutral. Sound level
				  measurements conducted for certification by exhaust system manufacturers shall
				  be made at an average steady-state engine speed of three-quarters of maximum
				  rpm. Sound level measurements conducted by licensed muffler certification
				  stations shall be made at an average steady-state engine speed of 3,000 rpm for
				  vehicles manufactured before 1972 for which the station does not have maximum
				  rpm data.
(d) Exhaust Sound Level
				  Measurement. The recorded exhaust system sound level of a stationary vehicle
				  shall be the highest reading obtained during the test, disregarding unrelated
				  peaks due to extraneous ambient noise. When there is more than one exhaust
				  outlet, the reported sound level shall be for the loudest outlet. When there
				  are two or more exhaust outlets separated by less than 12 in. (305 mm),
				  measurements shall be made on the outlet closest to the side or rear of the
				  vehicle (Figure 4). The sound level for motor vehicles with manufacturers'
				  gross vehicle ratings of less than 6,000 lb (2,722 kg), except motorcycles,
				  shall not exceed the following limit:
(1)
				  Sound Level Limit. The exhaust noise shall not exceed 95 dB(A).
(2) Exception. The exhaust noise of vehicles
				  manufactured after 1967 may exceed 95 dB(A) if the replacement parts are no
				  louder than the original equipment or "factory duplicate" system and the total
				  sound level of the vehicle when tested in accordance with Sections
				  1040 through
				  1049 of this title complies with
				  the limits in Vehicle Code Section
				  27205 for the
				  year of manufacture of that vehicle.