STARTING AND OPERATING 115 Engine Warm-Up Vehicle speed is 0mph (0km/h). This operating mode may last for up to an hour of idle time, or around 20minutes of driving time. Avoid full throttle operation when the engine is cold. When starting a cold engine, bring the engine up to operating speed slowly to allow the oil pressure to stabilize as the engine warms up. Applying the throttle will cancel fast idle. Operating the exhaust brake at idle will greatly improve warm-up rate and will help keep the engine close to operating temperature during extended idle. E NGINE I DLING Your truck may have been ordered with an optional voltage monitoring idle up feature.
If a load is placed on the electrical system while the truck is in PARK, this feature will attempt to maintain normal system voltage by automatically increasing engine idle speed. You may notice several consecutive increases in idle speed, up to a maximum of 1,450 RPM, as the system will attempt to utilize the smallest increase in idle speed necessary to maintain normal system voltage. The idle speed will return to normal when either the electrical load is removed, or when the brake pedal is applied. NOTE: High-speed, no-load running of a cold engine can result in excessive white smoke and poor engine performance.
No-load engine speeds should be kept under 1,000 RPM during the warm-up period, especially in cold ambient temperature conditions. Your vehicle is equipped with an engine warm-up protection feature that may limit engine performance after cold starting at low ambient temperatures. The length of time engine speed is limited is dependent upon engine coolant temperature. Engine speed may be briefly limited to 1,000 RPM after starting with coolant temperature below freezing conditions, and may be limited to 1,000 RPM for up to approximately two minutes under more severe cold conditions. Avoid prolonged idling.
Long periods of idling may be harmful to your engine because combustion chamber temperatures can drop so low that the fuel may not burn completely. Incomplete combustion allows carbon and varnish to form on piston rings, engine valves, and injector nozzles. Also, the unburned fuel can enter the crankcase, diluting the oil and causing rapid wear to the engine. 4 NOTE: For instrument cluster display messages related to the vehicle's exhaust system Ъ page81.
Idle-Up Feature If the engine is allowed to idle or the truck is driven on low engine speed drive cycles for more than two hours, the system will automatically enter an emissions operating mode that will increase the engine idle speed to 900 RPM (1,050 RPM for Chassis Cab). While in this mode, which is designed to help maintain the Diesel Particulate Filter, the engine idle speed will return to normal when the brake pedal is applied. A small change in engine tone or a slight change in engine performance while accelerating may also be noticeable at speeds below 20mph (32km/h).
The driver-controlled high idle speed feature will help increase cylinder temperatures and provide additional cab heat, however, excessive idling may still cause the exhaust after-treatment system to not properly regenerate. Extended periods of idle time should be avoided. NOTE: If ambient temperatures are low and the coolant temperature is below 180°F (82°C), the engine idle speed will slowly increase to 1,000 RPM after two minutes of idle, if the following conditions are met: The Idle-Up feature uses the Cruise Control buttons to increase engine idle speed and quickly warm the vehicle's interior. Foot is off brake pedal and throttle pedal. Automatic transmission is in PARK.