Engine not running smoothly / (irregular operation)

Make: Alfa Romeo
Model: GT Factory Service Manual
Year: 2003–2010
Section: Engine › Engine not running smoothly / (irregular operation)

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Fault diagnosisEngine not running smoothly / (irregular operation)

ENGINE NOT RUNNING SMOOTHLY / (IRREGULAR OPERATION)

1.8 T.SPARK, 2.0 JTS, 3.2 V6

During driving, the engine misses and loses performance

1.8 T.SPARK

During driving, the engine misses and loses performance

1.8 T.SPARK, 2.0 JTS, 3.2 V6

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: The condition of the air intake circuit; That there are no faults in the air filter The seal of the diesel pipes That there is no water, petrol, paraffin or dirt in the fuel tank and filter That the battery earth is correctly fixed That there no obstructions in the exhaust system	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
			Air filter blocked	Replace the filter element Op. Op. 1048A14 AIR CLEANER FILTERING ELEMENT - REPLACE.
			Leak from diesel pipes	Eliminate the leaks
			Presence of water, petrol, parffin or dirt detected.	Clean the tank and pipes and replace the filter element Op. Op. 1044B20 FUEL FILTER FILTERING ELEMENT - REPLACE
			Loose battery earth terminal	Restore the correct fixing of the earth cable
			Obstruction in the exhaust system	Replace the damaged system component
1	CHECK 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; The plausibiilty of 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, reproducting the conditions in which the fault arises, keeping the diagnostic socket connected Check: For errors in the control unit; The plausibiilty of the parameters	Continue to Step 3	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 the engine management control unit and the diagnostic connector.
3	Continue as instructed by the tester	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. Op. 1060G80 DS ELECTRIC INJECTION CONTROL UNIT - R R

2.0 JTS

During driving, the engine misses and loses performance

1.8 T.SPARK

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the condition of the air filter the state of the spark plugs and leads; battery earth correctly fixed See See E1010 SUPPLY	Continue to Step 1	Filter element dirty, damaged or incorrectly fitted	Replace or refit filter element correctly Op. Op. 1048A14 AIR CLEANER FILTERING ELEMENT - REPLACE.
			Spark plugs dirty or damaged	Replace the spark plugs Op. Op. 5510D10 SPARK PLUGS - R+R
			Spark plug leads damaged	Replace the spark plug leads
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 See table Z50 MIXTURE STRENGTH ERROR
			''Misfire'' error detected	See table See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL 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 See table Z50 MIXTURE STRENGTH ERROR
			''Misfire'' error detected	See table See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL 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	CHECK ON FUEL PRESSURE	All OK	Problems met	Operation
	Check, if necessary on the road (to reproduce the conditions in which the fault arises), the fuel supply pressure Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE	Continue to Step 4	Pressure not correct: obstructions in fuel delivery pipe	Remove the obstructions in the fuel pipe, and if necessary replace it Op. Op. 1040A30 OIL SEAL COVER, FLY WHEEL SIDE - R + R AND REPLACE SEALS
			Pressure not correct: tank insufficiently ventilated	Restsore the tank ventilation
			Pressure not correct: fuel pump electrical circuit broken	Repair fuel pump electrical circuit See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
			Pressure incorrect: fuel pump damaged	Replace fuel pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	CHECK AIR CONDITIONING SYSTEM	All OK	Problems met	Operation
	Road test the vehicle and check whether the fault is affected by whether or not the air conditioner is switched on	Continue to Step 5	Fault present only with the air conditioner on	See table See table L10 CLIMATE CONTROL NOT COOLING
5	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''

2.0 JTS

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: That the battery is properly connected to earth See See E1010 SUPPLY Condition of air intake circuit The condition of the spark plugs Quality of the fuel Check engine wiring earths	Continue to Step 1	Earth fastening not correct	Restore correct fixing
			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 Op. Op. 5510D10 SPARK PLUGS - R+R
			Impurities in the fuel	Clean the fuel tank
			Earths faulty	Restore correct fixing
1	CHECK 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 plausibiilty of the parameters	Continue to Step 2	Error detected	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Inconsistent parameter	Anaylze the factors that have caused this inconsistency
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions under which the fault arises, keeping the diagnostic equipment connected Check: That there are no faults in the engine management control unit The plausibiilty of the parameters, in particular: Rail pressure - rail pressure setting Injection times Rpm (graphic acquisition of the signal is best) Engine temperature	Continue to Step 3	Error detected	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Inconsistent parameter	Anaylze the factors that have caused this inconsistency
3	LOW PRESSURE CIRCUIT CHECK	All OK	Problems met	Operation
		Continue to Step 4	Incorrect pressure: obstructions in the fuel delivery pipe	Remove the obstructions in the fuel pipe, and if necessary replace it
			Pressure not correct: tank insufficiently ventilated	Restsore the tank ventilation
			Pressure not correct: petrol pump damaged or not correctly supplied	Replace fuel pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
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 Op. 1056F54
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 Op. 1056F52
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 Op. 1056F72
7	CHECK ON INJECTORS	All OK	Problems met	Operation
	Check the continuity/insulation of the injector wiring; in particular, make sure that the injector operating signal is present See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 8	No signal, wiring broken	Renew the wiring See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 8	No signal, wiring not broken	Replace engine management control unit Op. 1056F82
8	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 See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 9	No supply/earth	Renew the wiring See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 9	No operating signal	Check the wiring between the coils and the ECU and, if necessary, replace the control unit Op. 1056F82
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 Op. Op. 1036C40 TIMING VARIATOR ON INLET CAMSHAFT IN CYLINDER HEAD R + R WITH SHAFT REMOVED
10	MODULAR MANIFOLD CHECK IN ACTIVE DIAGNOSIS	All OK	Problems met	Operation
	Check the operation of the modular manifold in active diagnosis	Continue to Step 11	Not working	Using a voltmeter (graphic is best) check the modular manifold operating signal and, if necessary, replace the modular manifold solenoid valve Op. 1072D44
11	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct Op. Op. 0510A20 TIMING GEAR WITH BELT DRIVE - CHECK - CARRY OUT OPERATION WITH CAM COVER(S) REMOVED AND TAPPETS ADJUSTED	Continue to Step 12	Timing not correct	Ensure that the timing is correct Op. Op. 1032B10 TOOTHED TIMING BELT - R + R FOR TIMING ADJUSTMENT OR REPLACEMENT
12	Continue as instructed by the tester	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

3.2 V6

During driving, the engine misses and loses performance

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: The condition of the air filter; That the battery is properly connected to earth See See E1010 SUPPLY	Continue to Step 1	Filter element dirty, damaged or incorrectly fitted	Replace or refit filter element correctly Op. Op. 1048A14 AIR CLEANER FILTERING ELEMENT - REPLACE.
		Continue to Step 1	Earth fastening not correct	Renew the wiring See See E1010 SUPPLY
1	CHECK 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 plausibiilty of the parameters	Continue to Step 2	Supply system error detected	Continue according to the instructions in See table See table Z50 MIXTURE STRENGTH ERROR
			Upstream Lambda sensor error detected	Continue according to the instructions in See table See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL 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 under which the fault arises, keeping the diagnostic equipment connected Check: That there are no faults in the engine management control unit The plausibiilty of the parameters	Continue to Step 3	Supply system error detected	Continue according to the instructions in See table See table Z50 MIXTURE STRENGTH ERROR
			Upstream Lambda sensor error detected	Continue according to the instructions in See table See table Z56 UPSTREAM LAMBDA SENSOR SIGNAL ERROR
			Sudden occurrence of another error in the control unit detected	Continue following the instructions for the diagnostic equipment
			Inconsistent parameter	Continue following the instructions for the diagnostic equipment
3	CHECK ON FUEL PRESSURE	All OK	Problems met	Operation
	Check fuel supply presure, on road if necessary (to reproduce the conditions under which the fault arises) Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE	Continue to Step 4	Pressure not correct: obstructions in fuel delivery pipe	Remove the obstructions in the fuel pipe, and if necessary replace it
		Continue to Step 4	Pressure incorrect: fuel pump damaged	Replace fuel pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	CHECK AIR CONDITIONING SYSTEM	All OK	Problems met	Operation
	Road-test the car and to see if the anomalous behaviour is affected by air conditioner activation	Continue to Step 5	Fault present only with the air conditioner on	Continue according to the instructions in See table See table L10 CLIMATE CONTROL NOT COOLING
5	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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