Idle speed is adjustable on Cat electronic engines. Consult your Cat dealer for information. The idle rpm is preset between 700 and 800 rpm.
Avoid excess idling. An engine can burn from
If extended idle time is required, control the engine rpm to 1000 rpm or above 1000 rpm. Ensure that the coolant temperature exceeds
Fast idle can be programmed within the range of 700 rpm to the top engine limit. Fast idle requires an "ON/OFF" switch on the dashboard. Consult your Cat dealer for assistance.
The idle shutdown timer can be programmed in order to shut down the engine after a specific time period of idling. The idle time can be programmed from 3 minutes to 1440 minutes (24 hours). If the idle shutdown timer is set to 0 minutes, the idle shutdown feature is disabled. If the setting of the timer is unknown, allow the engine to idle. Observe the time that elapses before the engine shuts down. The following conditions must be met in order to activate the idle shutdown timer:
- The idle shutdown feature must be selected.
- No vehicle speed is detected by the Electronic Control Module (ECM).
- The engine is not under load.
- The engine is at operating temperature.
After the vehicle is stationary, the idle shutdown timer begins. The engine can be operating at low idle or at an idle rpm that is selected by the idle governor. The "CHECK ENGINE/DIAGNOSTIC" lamp will flash rapidly for 90 seconds prior to shutdown. Movement of the vehicle automatically resets the idle shutdown timer to the programmed setting.
The following conditions must be met in order to override the idle shutdown timer:
- Program the "ALLOW IDLE SHUTDOWN OVERRIDE" to "YES".
- The "CHECK ENGINE/DIAGNOSTIC" lamp will flash rapidly for 90 seconds prior to shutdown. Depress the service brake or the clutch pedal during the 90 seconds when the "CHECK ENGINE/DIAGNOSTIC" lamp flashes.
After an idle shutdown, the engine can be restarted without turning the ignition switch to the OFF position.
The override function is disabled if the "ALLOW IDLE SHUTDOWN OVERRIDE" is programmed to "NO".
Cat electronic engines do not require long warm-up periods that needlessly waste fuel. Typically, the engine should be at normal operating temperature in a few minutes. Begin operating the engine at low load. After normal oil pressure is reached and the temperature gauges begin to rise, the engine may be operated at full load.
To get the vehicle in motion, use a gear that will result in a smooth start. Move the load without increasing the engine rpm above low idle or without slipping the clutch. Engage the clutch smoothly. Slipping the clutch and engaging the clutch can cause stress to occur on the drive train and can also cause fuel to be wasted.
Use progressive shifting techniques. Progressive shifting is using only the rpm that is required in order to upshift into the next gear. Progressive shifting improves fuel economy.
- Keep the engine rpm to a minimum. Use an rpm that is from 1400 to 2000 rpm.
- Use only enough rpm to pick up the next gear.
Progressive shifting also reduces the acceleration rate. Top gear is reached sooner because less time is needed to synchronize the gears during shifting. In addition, the engine is operating at the highest range of torque.
The amount of rpm that is required to upshift increases as the vehicle speed increases, unless upshifts are made on upgrades. Experience with the vehicle will show the amount of rpm that is required to upshift under various conditions.
Note: These engines may be programmed to encourage progressive shifting. The acceleration rate may slow down at certain rpm in lower gears. If this occurs, progressive shift parameters may have been programmed into the ECM. Progressive shift parameters will limit the rpm when the vehicle is driven in higher gears. These parameters may be protected by customer passwords. If the vehicle can be operated in a higher gear at a vehicle speed that is desired, select the highest gear that is available to pull the load. This recommendation will help to obtain fuel economy. The engine will be operating at the lowest rpm that is required to pull the load.
An efficient vehicle performs the desired amount of work while the power demand on the engine is minimized. The following factors are major contributors to power demand:
- Aerodynamic drag (wind resistance)
- Rolling resistance of the tires
- Gross weight of the vehicle
- Losses in the drive train and the load from the engine driven accessories
For more information about vehicle efficiency, refer to Special Publication, LEDT2254, "CAT Answers Your Questions About Truck Performance".
Fuel is the largest single operating cost for on-highway vehicle engines. Improved fuel economy can have a substantial impact on operating profit. The following items are the most significant factors that influence vehicle fuel economy:
- Driver techniques
- Vehicle efficiency
- Operating conditions
- Engine efficiency
A No. 1 grade of fuel contains less energy per volume and increases fuel consumption. A greater volume of fuel must be injected in order to yield the same amount of work as a No. 2 fuel. The difference in the fuel economy between the two grades of fuel can be as great as
For more information about fuel economy, refer to Special Publication, LEDT2254, "CAT Answers Your Questions About Truck Performance".
Rolling hills provide a great opportunity to reduce fuel consumption. Avoid downshifting on small hills. The vehicle should not be downshifted even if the engine must be lugged down to an rpm that is below the peak torque rpm. When the vehicle is going down a hill, use gravity instead of the engine power to regain vehicle speed.
On grades that require more than one downshift, allow the engine to lug to peak torque rpm. If the rpm stabilizes with the engine running at peak torque rpm or above peak torque rpm, remain in that gear.
Long steep down grades should be anticipated. Vehicle speed should be reduced before cresting the top of a hill and proceeding down a long steep grade. Minimize the amount of braking that is used in order to maintain a safe speed for maximizing fuel efficiency.
The ability of the engine to hold the vehicle back increases with engine rpm. Select a gear that runs the engine near the high engine rpm limit for long steep hills when braking is required.
Speed reductions and future stops should be anticipated. Downshifts should be avoided. The amount of braking should be minimized in order to improve fuel consumption. By coasting to a stop, a vehicle can travel a considerable distance without consuming any fuel.
Vehicles that are driven faster consume more fuel. Increasing the cruising speed from
The functionality of the cruise control can vary depending on the vehicle manufacturer. The Cruise Control switch may be programmed to operate in one of two modes:
- The SET position may operate as the SET/ACCEL SWITCH position or the RESUME/DECEL position.
- The RESUME position may operate as the SET/DECEL position or the RESUME/ACCEL position.
Refer to the markings on the Cruise Control switch or refer to your "Truck Service Manual".
Perform the following steps in order to set the Cruise Control:
- After accelerating to the desired speed, turn the "ON/OFF" switch to the ON position.
- Press the "SET/RESUME" switch to the SET position.
The ECM will control the vehicle speed until the clutch pedal or the service brake is depressed or the "ON/OFF" switch is turned to the OFF position.
Note: The vehicle can also be accelerated to the desired speed and the cruise control speed can be set by pressing the "SET/RESUME" switch to the ACCEL position.
Perform the following step in order to reset the Cruise Control:
- Press "RESUME" and the vehicle will return to the set speed.
Momentarily pressing or bumping the "SET/RESUME" switch to the ACCEL position will increase vehicle speed by 1 mph. Press the switch to the DECEL position in order to decrease the speed by 1 mph. The operating range of the cruise control has been programmed into the ECM.
The Cruise Control can be programmed to operate in one of two modes, "Soft Cruise = YES" or "Soft Cruise = NO".
Soft Cruise Control provides an operating range of
When "Soft Cruise = NO" is programmed, the "SET" speed is maintained. Consult your Cat dealer for more information.
The cruise control function of the electronic engine works as an engine speed governor when the vehicle is stationary or when the vehicle is operated at a vehicle speed below the idle vehicle speed limit. The engine speed governor is activated and deactivated in the same way as the cruise control.
The engine speed governor will operate at any engine rpm from low idle to the maximum idle rpm limit. The maximum idle rpm limit is less than the rated engine rpm. The maximum idle governor speed is a Customer Specified Parameter.
Perform the following procedure in order to activate idle mode:
- Set the "ON/OFF" switch to the ON position. The throttle can then be used to determine the desired engine rpm.
- When the desired engine rpm is reached, place the "SET/RESUME" switch to the SET position and release the switch. The engine rpm will be maintained at this speed.
Note: If the "SET/RESUME" switch is held for more than one second in the ACCEL position, the ECM will increase the engine rpm until the "SET/RESUME" switch is released. If the parameter is programmed, the ECM will increase the engine rpm up to the idle engine rpm limit, or to the top engine limit (TEL).
Perform one of the following procedures in order to disengage the idle mode:
- Move the "Cruise/Idle ON/OFF" switch to the OFF position.
- Depress the clutch pedal.
- Depress the service brake pedal.
Perform the following procedure in order to resume the idle mode:
- Ensure that the "Cruise/Idle ON/OFF" switch is in the ON position.
- Move the "SET/RESUME" switch momentarily to the RESUME position.
Note: If the "SET/RESUME" switch is held for more than one second in the DECEL position, the ECM will decrease the engine rpm until the switch is released. A new set rpm is established when the switch is released.
For optimum performance, allow the engine to lug downward to peak torque rpm (1440 to 1550 rpm) before downshifting. Continue to downshift in this manner until a gear that maintains the desired speed is reached. Continue to operate at a low rpm (1440 to 1550 rpm) if the vehicle will proceed to the top without a downshift. Begin upshifting as the grade of the hill decreases and the engine begins to accelerate above 2000 rpm. Driving in this manner will provide optimum performance and fuel economy.
Note: Allowing the engine to lug below peak torque is permissible if the vehicle is cresting the top of a hill. However, extended operation at an engine rpm that is below peak torque (1400 rpm) will raise the exhaust temperature and the cylinder pressure. A higher exhaust temperature and a higher cylinder pressure can lead to reduced engine service life.
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DO NOT allow the engine rpm to exceed 2900 rpm, engine damage can result. |
On a downgrade, do not allow the vehicle to coast while the clutch pedal is depressed or while the transmission is in the NEUTRAL position. If a power loss is not desired, disengage the Cruise Control.
Select the correct gear that does not allow the engine rpm to exceed 2900 rpm. If equipped, use the Cat compression brakes to control the speed of the vehicle. As a basic rule, select the same gear that would be required to go up the grade. Refer to the rated rpm (full load) that is on the engine Information Plate.
If the vehicle is equipped with a Cat compression brake, maximum braking power occurs over 2200 rpm. Occasionally, when heavy loads or steep grades are encountered, it may be necessary to descend using a gear that is lower than the gear that is used to ascend.
The compression brake will not operate during the following conditions. The following conditions will temporarily interrupt the operation of the compression brake:
- The temperature of the engine coolant is below
70 °C (158 °F) . - The engine speed is below 1400 rpm and the vehicle speed is below
24 km/h (15 mph) . If low braking speed is desired, choose a transmission gear that will maintain the engine rpm above 1400 rpm.
Refer to this Operation and Maintenance Manual, "Compression Brake" for more information.
Reduction of Particulate Emissions
The diesel particulate filter (DPF) and the aftertreatment regeneration device (ARD) work together in order to reduce particulate emissions. The DPF collects the soot and the engine oil in the exhaust. The DPF converts the soot into a gas which is released into the atmosphere. The DPF converts the engine oil into ash. Ash from the engine oil remains in the DPF until the ash is cleaned out of the DPF. This process is called regeneration.
The temperature of the DPF must be above a particular value in order for regeneration to occur. The exhaust gas provides heat for the regeneration process. There are two types of regeneration:
Passive Regeneration - The engine provides sufficient exhaust gas temperature for regeneration.
Active Regeneration - The duty cycle of the engine does not provide sufficient exhaust temperature for passive regeneration. The ARD operates in order to raise the temperature of the exhaust gas. When the regeneration process is complete, the ARD turns off.
The driver will receive information on the status of the ARD from dash lamps and the driver will be able to request a regeneration by using a switch. Refer to this Operation and Maintenance Manual, "Monitoring System" for more information.