Engine not running smoothly / (losing power)

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2004
Section: Engine › Engine not running smoothly / (losing power)

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Fault diagnosisEngine not running smoothly / (losing power)

ENGINE NOT RUNNING SMOOTHLY / (LOSING POWER)

1.6 TS, 2.0 TS

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the state of the spark plugs and leads; the condition of air filter the condition of the air intake circuit absence of obstructions in the catalytic converter	Continue to Step 1	Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10
			Spark plug leads damaged	Replace the spark plug leads Op. 5510D14
			Air intake circuit fault	Eliminate the problem
			Catalyzer obstructed	Replace the exhaust manifold Op. 1072C12
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; plausibility of all the parameters	Continue to Step 2	'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR
			'Misfire' error detected	See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Inconsistent parameter	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions in which the fault arises, keeping the diagnostic equipment connected. Check: that there are no faults in the engine management control unit; plausibility of all the parameters	Continue to Step 3	'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR
			'Misfire' error detected	See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Inconsistent parameter	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems met	Operation
	Road test the vehicle and check the fuel supply pressure Op. 0510C10in the conditions that lead to the anomaly	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove restrictions
			Insufficient fuel pressure: valve obstructed	Replace the tank cap Op. 1040A40
			Insufficient fuel pressure: regulator out of calibration	Replace the pump assembly Op. 1040A70
			Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
			Low fuel pressure: clogged filter	Replace the pump assembly Op. 1040A70
4	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists: control unit defective	Replace control unit Op. 1056B82 Search for the fault starting from another symptom'

1.9 JTD 8V

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: that there are no leaks from the fuel system the condition of the air intake circuit that there are no obstructions in the catalyzer that there is no water in the diesel filter	Continue to Step 1	Fuel leaks	Eliminate the water from the diesel
			Fault in air intake circuit	Repair the air intake circuit
			Obstruction in the catalyzer	Replace the catalyzer
			Water in diesel filter	Clean the tank and replace the filter
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; plausibility of all the parameters	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Unreliable parameters	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle keeping the diagnostic instrument connected. Make sure that the conditions in which the problem occurs are reproduced check for errors in the control unit plausibility of all the parameters	Continue to Step 3	Errors suddenly occur in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Parameters off scale	Continue following the instructions for the diagnostic equipment
3	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the pedal switch is working properly See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 4	Brake pedal does not return	Eliminate the cause of the sticking
			Switch faulty	Replace the switch
			Wiring short-circuit (intermittent)	Restore connection See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
4	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists: control unit defective	Search for the fault starting from another symptom'

1.9 JTD 16V

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: that there are no leaks from the fuel system the condition of the air intake circuit the correct operation of the exhaust system; that there is no water in the diesel filter	Continue to Step 1	Fuel leaks	Restore the correct seal for the pipes, if necessary, replace them
			Fault in air intake circuit	Repair the air intake circuit
			Obstruction in the exhaust system	Replace the damaged system component
			Water in diesel filter	Clean the tank and replace the filter
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check: for errors in the control unit plausibility of all the parameters	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	unreliable parameters	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle keeping the diagnostic instrument connected. Make sure that the conditions in which the problem occurs are reproduced check for errors in the control unit plausibility of all the parameters	Continue to Step 3	Errors suddenly occur in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Parameters off scale	Continue following the instructions for the diagnostic equipment
3	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the pedal switch is working properly See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT	Continue to Step 4	Brake pedal does not return	Eliminate the cause of the sticking
			Switch faulty	Replace the switch
			Wiring short-circuit (intermittent)	Restore connection See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
4	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	The fault persists	Search for the fault starting from another symptom

All versions

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: if there is service information on the subject the condition of the air intake circuit the condition of the spark plugs check engine wiring earths	Continue to Step 1	Air intake circuit fault	Restore the correct operation of the intake circuit
			Spark plugs not the type recommended by the manufacturer	Replace the spark plugs
			Earths faulty	Renew the wiring See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
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; plausibility of all the parameters	Continue to Step 2	Error in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Inconsistent parameter	Analyze the causes that have led to this inconsistency
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions in which the fault arises, keeping the diagnostic equipment connected. check that there are no faults in the engine management control unit; the plausibility of the parameters, in particular: rail pressure - rail pressure setting, air mass, injection times, upstream Lambda voltage	Continue to Step 3	Inconsistent parameter	Analyze the causes that have led to this inconsistency
3	LOW FUEL PRESSURE CIRCUIT ROAD TEST	All OK	Problems met	Operation
	Road test the vehicle and check the fuel supply pressure in the conditions that lead to the anomaly	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove the blockages and replace the pipes if necessary
		Continue to Step 4	Low fuel pressure: defective pump	Replace the fuel pump assembly Op. 1040A70
4	RAIL PRESSURE SENSOR CHECK	All OK	Problems met	Operation
	Check the operation of the rail sensor	Continue to Step 5	Pressure sensor faulty	Replace sensor
5	PRESSURE REGULATOR CHECK	All OK	Problems met	Operation
	Check that the voltage regulator is working	Continue to Step 6	Pressure regulator faulty	Replace the pressure regulator
6	HIGH PRESSURE PUMP CHECK	All OK	Problems met	Operation
	Check the operation of the high pressure pump	Continue to Step 7	High pressure pump faulty	Replace high pressure pump
7	IGNITION OPERATION CHECK	All OK	Problems met	Operation
	Check the continuity/insulation of the supply circuit and the coil operation; in particular, make sure that the coil operating signal is present See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 8	No supply/earth	Renew the wiring See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 8	No operating signal	Check the wiring between the coils and the ECU and, if necessary, replace the control unit See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
8	MODULAR MANIFOLD CHECK IN ACTIVE DIAGNOSIS	All OK	Problems met	Operation
	Check the operation of the modular manifold in active diagnosis	Continue to Step 9	Not working	Using a voltmeter (graphic is best) check the modular manifold operating signal and, if necessary, replace the modular manifold solenoid valve
9	PHASE TRANSFORMER CHECK IN ACTIVE DIAGNOSIS	All OK	Problems met	Operation
	Check the operation of the phase transformer in active diagnosis	Continue to Step 10	Not working	Using a voltmeter (graphic is best) check the transformer operating signal and, if necessary, replace the transformer
10	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. 1056B82

3.2 V6

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the condition of air filter the condition of the air intake circuit	Continue to Step 1	Filter blocked	Replace the filter element Op. 1048A14
		Continue to Step 1	Air intake circuit fault	Eliminate the problem
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; plausibility of all the parameters	Continue to Step 2	'Supply system' error detected	Continue according to the instructions in See table Z50 MIXTURE STRENGTH ERROR
			'Misfire' error detected	Continue according to the instructions in See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Inconsistent parameter	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions in which the fault arises, keeping the diagnostic equipment connected. Check: that there are no faults in the engine management control unit; plausibility of all the parameters	Continue to Step 3	'Supply system' error detected	Continue as instructed in the Table See table Z50 MIXTURE STRENGTH ERROR
			'Misfire' error detected	Continue as instructed in the Table See table Z53 MISFIRE ERROR
			Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
			Parameters inconsistent	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems met	Operation
	Road test the vehicle and check the fuel supply pressure Op. 0510C10in the conditions that lead to the anomaly	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove the blockages and replace the pipes if necessary
		Continue to Step 4	Low fuel pressure: defective pump	Replace the fuel pump assembly Op. 1040A70
10	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 control unit Op. 1056B82

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