D02 Engine working irregularly (misfiring)

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2002
Section: Engine › D02 Engine working irregularly (misfiring)

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Fault diagnosisD02 Engine working irregularly (misfiring)

D02 Engine working irregularly (misfiring)

Under conditions of constant load and speed, there are intermittent decreases in performance, even prolonged

Step	Test procedure	Result	Action
0	PRELIMINARY CHECKS First check: the state of the spark plugs and leads; the condition of the air filter the condition of the air intake circuit for any obstructions of the catalyzer	OK	Move onto step 1
		Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10 End of diagnosis
		Spark plug leads damaged	Replace spark plug leads End of diagnosis
		Air intake circuit check	Eliminate the problem End of diagnosis
		Catalyzer obstructed	Replace the exhaust manifold Op. 1072C12 End of diagnosis
1	CHECK WITH DIAGNOSTIC EQUIPMENT Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	OK	Move onto step 2
		'Supply system ' error detected	See table Z50 MIXTURE STRENGTH ERROR End of diagnosis
		'Misfire' error detected	See table Z53 MISFIRE ERROR End of diagnosis
		Another error detected in the control unit	Continue following the instructions for the diagnostic equipment End of diagnosis
		Incoherent parameter	Continue following the instructions for the diagnostic equipment End of diagnosis
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT Road test the vehicle, reproducing the conditions in which the fault arises, keeping the diagnostic equipment connected Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	OK	Move onto step 3
		'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR End of diagnosis
		'Misfire' error detected	See table Z53 MISFIRE ERROR End of diagnosis
		Another error detected in the control unit	Continue following the instructions for the diagnostic equipment End of diagnosis
		Incoherent parameter	Continue following the instructions for the diagnostic equipment End of diagnosis
3	FUEL PRESSURE ROAD TEST Road test the vehicle and check the fuel supply pressure Op. 0510C10 in the conditions that lead to the anomaly	OK	Move onto step 4
		Insufficient fuel presure: pipes obstructed	Eliminate the obstructions End of diagnosis
		Insufficient fuel supply pressure: valve obstructed	Replace the tank cap Op. 1040A40 End of diagnosis
		Insufficient fuel supply pressure: regulator stuck	Replace the pump assembly Op. 1040A70 End of diagnosis
		Insufficient fuel pump: pump faulty	Replace the pump assembly Op. 1040A70 End of diagnosis
		Fuel pressure insufficient: filter blocked	Repplace the pump assembly Op. 1040A70 End of diagnosis
4	CORRECT OPERATION CHECK Check that the fault is no longer present	OK	Incorrect selection of diagnostic procedure
4		The fault persists: control unit defective	Replace control unit Op. 1056B82 Incorrect selection of diagnostic procedure

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Parts & tools for this job For 2000 Alfa Romeo 147

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