D10 ENGINE IDLE IRREGULAR - Alfa - 156 - eLearn

3233019 - D10 ENGINE IDLE IRREGULAR

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.)

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: condition of air filter the condition of the air intake circuit the condition of the fuel filter	Continue to Step 1	Filter element dirty or damaged	Replace the filter element Op. 5548A14
			Air intake circuit component damaged	Replace the component (see Assembly 1048A)
			Fuel filter dirty	Replace the filter element Op. 1044B20
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket check that there are no faults in the engine management control unit the plausibility of all the parameters.	Continue to Step 2	An error is detected in the control unit	Continue according to the instructions for the diagnostic equipment
		Continue to Step 2	Lack of dialogue with the control unit	Restore the connection between the engine management control unit and the diagnostic connector ( See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT )
2	LOW PRESSURE CHECK	All OK	Problems met	Operation
	Check the fuel supply circuit, low pressure side: if necessary, use the diagnostic equipment (Examiner) to measure the pressure values	Continue to Step 3	Pressure not correct: fuel filter faulty	Replace the fuel filter Op. 1044B10
			Pressure not correct: electric pump faulty	Replace the electric pump Op. 1040A70
			Pressure not correct: low pressure pipes faulty	Replace the low pressure pipes (see Assembly 1060F)
3	HIGH PRESSURE CHECK	All OK	Problems met	Operation
	Check the fuel supply circuit, high pressure side: for example, using the diagnostic equipment (Examiner) to measure the pressure values	Continue to Step 4	Pressure not correct: pressure pump faulty	Replace the pressure pump Op. 1060E10
			Pressure not correct: manifold faulty	Replace the manifold Op. 1060F30
			Pressure not correct: injectors faulty	Replace the injectors Op. 1060F10
4	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 5	Compression values not correct	Restore the correct cylinder compression, for example, checking the seal of the injectors Op. 1060F10 and the cylinders (see OVERHAULING ENGINE, Subassembly 1004)
5	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct. Op. 1036H14	Continue to Step 6	Clearance not correct	Restore the correct valve clearance. Op. 1036H18
6	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists	Search for the fault starting from another symptom'

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.)

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check: the condition of the air intake circuit condition and correct operation of the air filter	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
		Continue to Step 1	Air filter blocked	Replace the filter element Op. 1048A14
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check: that there are no errors in the control unit plausibility of all the parameters carry out active diagnosis of E.G.R. solenoid	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
			unreliable parameters	Continue following the instructions for the diagnostic equipment
			Lack of dialogue with the control unit	Restore the connection between engine management control unit and diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Solenoid not working	Check wiring continuity See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Solenoid not working	Replace the solenoid valve Op. 1080C74
2	CHECK ON FUEL FILTER	All OK	Problems met	Operation
	Check the operation of the fuel filter	Continue to Step 3	Presence of water, petrol, paraffin or dirt detected	Clean the tank and pipes and replace the diesel filter cartridge Op. 1044B20
3	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct.	Continue to Step 4	Valve clearance not correct	Adjust the tappets Op. 1036H10
4	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 6	Cylinder compression insufficient	Continue to Step 5
5	CHECKING CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R.R. on head to check the valve seal and check the condition of the cylinders/piston rings	Continue to Step 6	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
6	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit faulty	Replace engine management control unit Op. 1060G80 Search for the fault starting from another symptom'