Idle speed is adjustable on Caterpillar electronic engines. Consult your Caterpillar dealer for information. The idle rpm is preset between 700 and 750 rpm.
Avoid excess idling. If the vehicle is parked for more than five minutes, stop the engine. 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 Caterpillar 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 three 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. The engine is not in Cold Mode.
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".
Cold mode is initiated if the coolant temperature is below
After the cold mode is completed, the engine should be operated at low rpm and low load until normal operating temperature is reached. The engine will reach normal operating temperature faster when the engine is operated at low rpm and low power demand. This method is faster than trying to reach operating temperature by idling with no load.
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It is not recommended that the vehicle be moved until the engine is out of cold mode. Power may be noticeably reduced if the vehicle is operated while the engine is in cold mode. At a speed above |
Cold mode is disabled if the throttle, the service brake, or the clutch (if equipped) is depressed. The rpm for cold mode operation drops to the programmed low idle speed in order to allow the transmission to be put into gear.
Caterpillar 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. This 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 1200 to 1600 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 are 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 of today's 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's power to regain vehicle speed.
On grades that require more than one downshift, allow the engine to lug to peak torque rpm. If the engine is running at peak torque rpm or above peak torque rpm and the rpm stabilizes, remain in that gear.
Long steep down grades should be anticipated. Reduce the speed of the vehicles before you crest the top of a hill and before you proceed 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 engine's ability 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 SET/DECEL position.
- The RESUME position may operate as the RESUME/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 one mph. Press the switch to the DECEL position in order to decrease the speed by one 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 Caterpillar dealer for more information.
Adaptive cruise control reduces the need to manually cancel cruise control when you approach a slower vehicle. The system responds by decreasing the cruise control set speed until a following distance is obtained. If the slower vehicle speeds up, the cruise control set speed will be adjusted in order to maintain the following distance. Adaptive cruise control will restore the original set speed when there are no vehicles within the range of control. Adaptive cruise control will not increase the cruise control set speed above the original setting. If the vehicle is approaching the target too rapidly, the ECM will turn off the cruise control.
Note: The following information is applicable to engines with the EatonTop 2 transmission.
The ECM controls the shifting of the two highest gears of the transmission. A downshift of one gear from the top gear will occur automatically. The downshift will occur when the load that is on the engine increases. An example of an increasing load would be climbing a hill.
The Throttle Activated Downshift feature is available in order to provide the operator with additional control of the gears for the Top 2 transmission. The Throttle Activated Downshift feature enables the operator to downshift faster than the automatic downshift.
The Throttle Activated Downshift enables the operator to downshift easily. It is useful for passing or for climbing hills. The following conditions must be met in order for the Throttle Activated Downshift to be used:
- The transmission is in the top gear.
- The engine rpm is below 1350 rpm for transmissions with ten speeds forward.
- The engine rpm is below 1450 rpm for transmissions with thirteen speeds forward.
- The engine rpm is below 1450 rpm for transmissions with eighteen speeds forward.
Downshifting One Gear From the Top Gear
In order to downshift one gear from the top gear, the following steps must be performed:
- Release foot from the throttle pedal.
- Fully depress the throttle pedal to the floor in order to provide full throttle.
To allow synchronization of the downshift, the engine rpm may increase by 400 rpm.
Upshifting To The Top Gear From One Gear Below The Top Gear
The transmission can be shifted to the top gear when the transmission is one gear from the top gear. In order to upshift to the top gear, slightly release the throttle from the full throttle position.
If the throttle is not slightly released, the transmission will automatically upshift to the top gear when the engine rpm reaches one of the following limits:
- 40 rpm below the programmed Top Engine Limit
- 40 rpm below the programmed Gear Down Protection limit
Preventing Downshifting One Gear From the Top Gear
In order to prevent downshifting one gear from the top gear, DO NOT release the throttle pedal and then provide full throttle.
If the conditions are met and the Throttle Activated Downshift is NOT desired, do not release the throttle and then provide full throttle. Continue to drive the vehicle. A downshift of one gear from the top gear will occur automatically. The downshift will occur when the load that is on the engine increases. An example of an increasing load would be climbing a hill.
Refer to the Eaton, "Driver Instructions" for more information on the Top 2 transmission.
For optimum performance of the engine, lug down the engine between 1100 rpm and 1200 rpm, before the transmission is downshifted. Continue to downshift in this manner until you reach a gear that maintains the desired speed. Continue to operate the engine at 1100 rpm to 1200 rpm if the vehicle will crest the top of the hill without a downshift in the transmission. Begin upshifting as the grade of the hill decreases and the engine begins to accelerate above 1600 rpm. This method of operation will provide optimum fuel economy and performance.
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 engine speeds below peak torque (1200 rpm) will raise the exhaust temperature and the cylinder pressure. This can lead to reduced engine service life.
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Do not exceed 2300 rpm in any situation or 2100 rpm if equipped with an auxiliary engine brake system. |
On downgrades, do not coast while the clutch pedal is depressed. Do not coast with the transmission in neutral. If no engine power is needed, disengage the Cruise Control.
Select the correct gear that does not allow the engine speed (rpm) to exceed 2300 rpm. Use the auxiliary brake in order to control the speed of the vehicle, if equipped. Usually, the same gear that would be used to go up a hill can be used to go down the hill. Refer to the rated rpm that is on the engine information film.