Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:99:p12
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 99 (pt 12/39)
Character Range: 1186099–1189256

meet the criteria defined by this Regulation for belonging to a compression ignition engine family.

              The difference between the highest and the lowest GERWHTC ( i.e. the highest GERWHTC minus the lowest GERWHTC) within a dual-fuel engine family shall not exceed 30 per cent.

              3.1.2.  Selection of the parent engine

              The parent engine of a dual-fuel engine family shall be selected according to the criteria defined by this Regulation for selecting the parent engine of a compression ignition engine family.

              4.  General requirements

              4.1. Operating modes of dual-fuel engines and vehicles

              4.1.1. Conditions for a dual-fuel engine to operate in diesel mode

              A dual-fuel engine may only operate in diesel mode if, when operating in diesel mode, it has been certified according to all the requirements of this Regulation concerning diesel engines.

              When a dual-fuel engine is developed from an already certified diesel engine, then re-certification is required in the diesel mode.

              4.1.2. Conditions for a HDDF engine to idle using diesel fuel exclusively

              4.1.2.1. HDDF Type 1A engines shall not idle using diesel fuel exclusively except under the conditions defined in section 4.1.3. for warm-up and start.

              4.1.2.2. HDDF Type 1B engines shall not idle using diesel fuel exclusively in dual-fuel mode.

              4.1.2.3. HDDF Types 2A, 2B and 3B engines may idle using diesel fuel exclusively.

              4.1.3. Conditions for a HDDF engine to warm-up or start using diesel fuel solely

              4.1.3.1. A Type 1B, Type 2B, or Type 3B dual-fuel engine may warm-up or start using diesel fuel solely. However, in that case, it shall operate in diesel mode.

              4.1.3.2. A Type 1A or Type 2A dual-fuel engine may warm-up or start using diesel fuel solely. However, in that case, the strategy shall be declared as an AES and the following additional requirements shall be met:

              4.1.3.2.1. The strategy shall cease to be active when the coolant temperature has reached a temperature of 343 K (70 °C), or within 15 minutes after it has been activated, whichever occurs first; and

       4.1.3.2.2. The service mode shall be activated while the strategy is active.

              4.2. Service mode

              4.2.1. Conditions for dual-fuel engines and vehicles to operate in service mode

              When its engine is operating in service mode, a dual-fuel vehicle is subject to an operability restriction and is temporarily exempted from complying with the requirements related to exhaust emissions, OBD and NOx control described in this Regulation.

              4.2.2. The operability restriction applicable to dual-fuel vehicles when they operate in service mode is the one activated by the "severe inducement system" specified in Annex 11 or, in the special case described in paragraph 4.2.2.3., the power limitation described in that section.

       4.2.2.1. Activation of the operability restriction

              The operability restriction shall be