4. On DBW vehicles, place the gear change selector in position «N» or «P». 5. Operate the mixture screw (1) to obtain a normal running speed, according to the model of the vehicle : a) D Vehicles all types (except DBW) : 650 + 25 rpm b) DBW Vehicles : 825 + 25 rpm 6. Operate the rich mixture screw (4) to obtain (use a for CO and CO2):: a) DX-DJ-DJ F Vehicles : Mixture in carbon monoxide (CQ) : 2 to 3,6 % : Mixture in carbonic gas (CO2) —: superior to 8 %