The 3126 Engine uses the hydraulic electronic unit injector (HEUI) for fuel injection. The HEUI eliminates many of the mechanical components that are used in a pump-and-line system. The HEUI provides increased control of the timing and increased control of the fuel air mixture. The timing advance is achieved by precise control of the unit injector timing. Engine rpm is controlled by adjusting the injection duration. A special pulse wheel provides information to the Engine Control Module (ECM) for detection of cylinder position and engine rpm.
The engine has built-in diagnostics in order to ensure that all of the components are operating properly. In the event of a system component failure, the operator will be alerted to the condition via the check engine light that is located on the dashboard. An electronic service tool can be used to read the numerical code of the faulty component or condition. Also, the cruise control switches can be used to flash the code on the check engine light. Intermittent faults are logged and stored in memory.
Starting The Engine
The engine's ECM will automatically provide the correct amount of fuel in order to start the engine. Do not hold the throttle down while the engine is cranking. If the engine fails to start in twenty seconds, release the starting switch. Allow the starting motor to cool for two minutes before using the starting motor again.
| NOTICE |
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Excessive ether (starting fluid) can cause piston and ring damage. Use ether for cold weather starting purposes only. |
Cold Mode Operation
The ECM will set the cold start strategy under the following conditions:
- the sum of the coolant temperature and the inlet air temperature is below 25 °C (109 °F).
Under these conditions, low idle rpm will be increased to 1000 rpm. The engine's power will also be limited.
Cold mode operation will be deactivated after any one of the following conditions:
- the sum of the coolant temperature and the inlet air temperature is above 35 °C (127 °F).
- thirteen minutes of running
- depressing the service brake
- depressing the throttle
- depressing the clutch
In automatic transmissions, the cold mode operation will be deactivated after any one of the following conditions:
- placing an automatic transmission in gear from the NEUTRAL position
- placing an automatic transmission in gear from the PARK position
After disabling, cold mode operation may ramp slowly back to 1000 rpm under any of the following conditions:
- the temperature conditions still exist.
- an automatic transmission is not in gear.
Cold mode operation varies the fuel injection amount for white smoke cleanup. Cold mode operation also varies the timing for white smoke cleanup. The engine operating temperature is usually reached before the walk-around inspection is completed. The engine will idle at the programmed low idle rpm in order to be put in gear.
After the cold mode is completed, the engine should be operated at low rpm 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.