The hydraulic electronic unit injector fuel system (HEUI) eliminates many of the mechanical components that are used in a pump-and-line system. The electronic control and hydraulic actuation also provide increased control of the timing and increased control of the fuel injection pressure. The timing advance is achieved by precise control of the unit injector timing. Engine speed is controlled by adjusting the injection duration. A special speed-timing wheel provides information to the Electronic Control Module (ECM) for detection of cylinder position and engine speed.
The engine has built-in diagnostics to ensure that all the components are operating properly. In the event of a system component failure, the operator will be alerted to the condition by the "Check Engine" light. An electronic service tool can be used to read the numerical code of the faulty component or condition. Intermittent faults are also logged and stored in memory.
The engine ECM will automatically provide the correct amount of fuel to start the engine. Do not hold the throttle down while the engine is cranking. If the engine fails to start in 20 seconds, release the starting switch. Allow the starting motor to cool for 2 minutes before using the starting motor again.
Engine cold mode is used to control fuel injection timing when the engine is cold. Engine cold mode changes the fuel injection timing to prevent engine damage. Engine cold mode also reduces white smoke. Engine cold mode is activated when the engine coolant temperature is below operating temperature.
Engine Starting with Ether Starting Aid
When the starting motor is engaged, the engine ECM determines the need for ether to be automatically injected into the engine, based on the coolant temperature. The engine ECM also determines the amount of ether that is injected, and the duration of the injection. Cat® Electronic Technician (ET) can be used to turn off the automatic injections.
The ECM automatically injects ether into the air inlet manifold when the following conditions are met:
- The ether control parameter is programmed to ON.
- The engine rpm is between 75 and 750 rpm.
- The jacket water coolant temperature is below 30 °C (86 °F).
The duration of ether injection varies linearly with the jacket water coolant temperature. The duration of ether injection varies within the range governed by post ether duration map. The Post ether duration map is active when engine speed is equal to 100 RPM less than the programmed low idle speed. The duration of ether injection is governed by the post ether map.
| Coolant Temperature | Post Ether Duration |
| −40° C | 15 seconds |
| −18° C | 10 seconds |
| 0° C | 5 seconds |
The longest duration of ether injection is 130 seconds even if the jacket water coolant temperature is less than -40 °C (-40 °F).
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| Illustration 1 | g00769594 |
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Temperature of the jacket water and duration of ether injection (Y) Temperature in ° C (X) Time in seconds | |
For troubleshooting, an override is available for the technician to actuate the ether system. By using Cat (ET), ether injection can be started and stopped. The ether solenoid will remain energized until any of the following conditions occur:
- Engine speed appears.
- The override for the service tool is used to terminate injection.
- The technician exits the override feature of the service tool.
The engine uses a strategy for the cold cylinder cutout to reduce white exhaust smoke after start-up and during extended idling in cold weather.
During a cold start and/or extended periods at low idle, the engine's Electronic Control Module (ECM) turns off one unit injector at a time in order to determine if each cylinder is firing. If a cylinder is firing, the ECM turns on the injector. If a cylinder is not firing, the injector is turned off. This cold cylinder cutout provides the following benefits: reduction of white smoke, improved engine starting, reduction in the use of ether injection and reduction of warm-up time.
Note: During operation of the cold cylinder cutout, the engine may seem to misfire. This is normal. No corrective measures are necessary.
The cold cylinder cutout is activated after all of the following conditions are met:
- The parking brake is engaged.
- The transmission is in neutral.
- The ground speed of the machine is zero.
- The jacket water coolant temperature is below
63 °C (145 °F) or the aftercooler coolant temperature is below3 °C (37 °F) . - Ten seconds after starting or three seconds after ether injection is completed.
- Ten minutes after extended idling of the engine has occurred.
The cold cylinder cutout is deactivated if any of the following conditions are met:
- The parking brake is disengaged.
- The transmission is placed in gear.
- The temperature of the jacket water rises above
70 °C (158 °F) . - The temperature of the aftercooler coolant rises above
10 °C (50 °F) . - The engine speed drops 100 rpm below low idle.
- Manual ether injection is used.
- The cold cylinder cutout is disabled with the Caterpillar Electronic Technician (Cat ET).
If the transmission is returned to the neutral position and the parking brake is engaged, the cold cylinder cutout will activate again after ten minutes, provided that the other conditions are met.
The Engine Idle Shutdown function stops the engine automatically when the machine has been idle for longer than the set time. The parameter can be enabled or disabled. The parameter is programmable between 3 and 60 minutes.
Delayed Engine Shutdown (If Equipped)
The "Delayed Engine Shutdown" strategy allows the engine to run after the engine start switch key is turned to the OFF position to allow for additional idle time to cool the engine and system components. The engine start switch key may be removed. This is an optional feature that can be enabled or disabled. The amount of time the feature is active and configurable between 4 and 10 minutes.
Note: There may be regulations that define the requirements for the operator and/or support personnel to be present when the engine is running.
Note: To override delayed engine shutdown and stop the engine, turn the engine start switch key to the STOP position. A warning message and/or audible alarm will be initiated and a fault code will be logged for informational purposes when bypassing the engine shutdown if the feature is enabled.
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| Illustration 2 | g02362719 |
Note: At any time during a delayed engine shutdown, the engine start switch key may be turned to the ON position. The engine may be placed back into service.