Engine not running smoothly / (hesistant)

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

‹ Prev Gear flashing on the display Next › Engine not running smoothly / (losing power)

Fault diagnosisEngine not running smoothly / (hesistant)

ENGINE NOT RUNNING SMOOTHLY / (HESISTANT)

3.2 V6

There is a (prolonged) fall in performance (flat spots) during acceleration

1.8 T.SPARK

There is a (prolonged) fall in performance (flat spots) during acceleration

3.2 V6

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Results of the tests
	Conduct a preliminary check on the condition of the air intake circuit	Move on to Step 1 1	Air intake circuit faulty	Restore the correct operation of the intake circuit
1	CHECK USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Connect the diagnostic test equipment (Examiner or other instruments) to the tester input. Check: that there are no faults in the engine management control unit; parameter plausibility	Move on to Step 2 1	"Fuel system" error detected	Proceed as instructed in the See table See table Z50 MIXTURE STRENGTH ERROR
			Another error detected in the control unit	Continue following the instructions for the diagnostic equipment
			Parameter not consistent	Continue following the instructions for the diagnostic equipment
2	ROAD TEST USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Carry out a road test reproducing the conditions in which the fault occurs, keeping the diagnostic equipment connected. Check: that there are no faults in the engine management control unit; parameter plausibility	Move on to Step 3 1	The sudden onset of an error in the control unit is detected	Continue following the instructions for the diagnostic equipment
		Move on to Step 3 1	Parameter not consistent	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE CHECK	All OK	Problems encountered	Operation
	Carry out a road test, reproducing the conditions in which the problem occurs. Check the fuel supply pressure Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE	Move on to Step 4 1	Pressure not correct: obstructions in the fuel supply pipe	Remove the obstructions in the fuel pipe, replace it if necessary
			Pressure not correct: tank not sufficiently ventilated	Restore the tank ventilation
			Pressure not correct: petrol pump damaged	Replace the petrol pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	CHECK ON CORRECT OPERATION	All OK	Problems encountered	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit defective	Replace the engine management control unit Op. 1056B82

2.0 JTS

There is a (prolonged) fall in performance (flat spots) during acceleration

1.8 T.SPARK

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Results of the tests
	First, check: status of spark plugs and leads; the condition of the air intake circuit	Move on to Step	Spark plugs dirty or damaged	Replace the spark plugs Op. Op. 5510D10 SPARK PLUGS - R+R
			Spark plug leads damaged	Replace spark plug leads
			Air intake circuit faulty	Eliminate the fault
1	CHECK USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Connect the diagnostic test equipment (Examiner or other instruments) to the tester input. Check: that there are no faults in the engine management control unit; parameter plausibility	Move on to Step 2	"Fuel system" error detected	Proceed as instructed in the TABLE See table Z50 MIXTURE STRENGTH ERROR
			Another error detected in the control unit	Continue following the instructions for the diagnostic equipment
			Parameter not consistent	Continue following the instructions for the diagnostic equipment
2	ROAD TEST USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Carry out a road test reproducing the conditions in which the fault occurs, keeping the diagnostic equipment connected. Check: that there are no faults in the engine management control unit; parameter plausibility	Move on to Step 3	The sudden onset of an error in the control unit is detected	Continue following the instructions for the diagnostic equipment
		Move on to Step 3	Parameter not consistent	Continue following the instructions for the diagnostic equipment
3	CHECK USING THE EXAMINER	All OK	Problems encountered	Operation
	Carry out active diagnosis of the variable valve timing and check that it is working properly	Move on to Step 4	Variable valve timing interrupted	Replace variable valve timing
4	VARIABLE VALVE TIMING OPERATING CHECK	All OK	Problems encountered	Operation
	Carry out a road test to ensure the vvt operates as required Check the operation of the vvt (hydraulic actuator) by carrying out Test 1056OA See Test 1056 PETROL INJECTION SYSTEM	Move on to Step 5	Variable valve timing defective	Replace the variable valve timing
			Variable valve timing wiring interrupted	Restore wiring
			Variable valve timing (hydraulic actuator) defective	Restore to operation
5	FUEL PRESSURE CHECK	All OK	Problems encountered	Operation
	Carry out a road test, reproducing the conditions in which the fault occurs. Check fuel supply pressure by carrying out Test 1056BY See Test 1056 PETROL INJECTION SYSTEM	Move on to Step 6	Pressure not correct: obstructions in the fuel supply pipe	Remove the obstructions in the fuel pipe, replace it if necessary Op. 1040B30 TUBAZIONE DI MANDATA COMBUSTIBILE (UNICA) - S.R.
			Pressure not correct: tank not sufficiently ventilated	Restore the tank ventilation
			Pressure not correct: fuel pump electric circuit interrupted	Restore fuel pump electric circuit See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
			Pressure not correct: petrol pump damaged	Replace the petrol pump assembly Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
6	CHECK ON CORRECT OPERATION	All OK	Problems encountered	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit defective	Replace the control unit Op. 1056B82 CENTRALINA (UNICA) DELL''IMPIANTO INIEZIONE/ACCENSIONE - S.R.

2.0 JTS

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: Whether there is service information on the subject The condition of the air intake circuit Spark plugs	Continue to Step 1	Air intake circuit fault	Restore the correct operation of the intake circuit
		Continue to Step 1	Spark plugs not the type recommended by the manufacturer	Replace the spark plugs Op. Op. 5510D10 SPARK PLUGS - R+R
1	CHECK USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Connect the diagnostic test equipment (Examiner or other instruments) to the tester input. Check: That there are no faults in the engine management control unit; Parameter plausibility	Move on to Step 2 1	Presence of errors	Continue following the instructions for the diagnostic equipment
		Move on to Step 2 1	Parameter not consistent	Continue as instructed by the Tester and analyse the facors that could give to the inconsistencies.
2	ROAD TEST USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Carry out a road test reproducing the conditions in which the fault occurs, keeping the diagnostic equipment connected. Check: that there are no faults in the control unit; Parameter plausibility, particularly: Rail pressure setting Air mass Engine temperature. Upstream lambda sensor voltage	Move on to Step 3 1	The sudden onset of an error in the control unit is detected	Continue following the instructions for the diagnostic equipment
		Move on to Step 3 1	Parameter not consistent	Continue as instructed by the Tester and analyse the facors that could give to the inconsistencies.
3	LOW PRESSURE CIRCUIT CHECK	All OK	Problems encountered	Operation
		Move on to Step 4 1	Pressure not correct: obstructions in the fuel supply pipe	Remove the obstructions in the fuel pipe, replace it if necessary
			Pressure not correct: tank not sufficiently ventilated	Restore the tank ventilation
			Pressure not correct: petrol pump damaged or not correctly supplied	Replace the petrol pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	RAIL PRESSURE SENSOR CHECK	All OK	Problems encountered	Operation
	Check the operation of the pressure sensor on the rail	Move on to Step 5 1	Pressure sensor fault	Replace the 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 encountered	Operation
	Check high pressure pump operation	Move on to Step 7 1	High pressure pump fault	Replace high pressure pump Op. 1056F72
7	INJECTOR CHECK	All OK	Problems encountered	Operation
	Check continuity/insulation of injector wiring. In particular, check injector pilot signal is present. See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Move on to Step 8 1	Signal not present, wiring broken	Restore wiring See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Move on to Step 8 1	Signal not present, wiring not broken	Replace the engine management control unit Op. 1056F82
8	CHECK VARIABLE VALVE TIMING IN ACTIVE DIAGNOSTIC MODE	All OK	Problems encountered	Operation
	Check variable valve timing operation when in active diagnostic mode	Move on to Step 9 1	Not operational	Use a voltmeter (preferably graphic) to check the vvt control signal. If necessary, replace the vvt Op. Op. 1036C40 TIMING VARIATOR ON INLET CAMSHAFT IN CYLINDER HEAD R + R WITH SHAFT REMOVED
9	CHECK MODULAR MANIFOLD IN ACTIVE DIAGNOSIS MODE	All OK	Problems encountered	Operation
	Check the operation of the modular manifold in active diagnosis mode	Move on to Step 10 1	Not operational	Use a voltmeter (preferably graphic) to check the modular manifold control signal. Replace the modular manifold solenoid if necessary Op. 1072D44
10	CHECK IGNITION OPERATION	All OK	Problems encountered	Operation
	Check continuity/insulation of coil supply and control circuit. In particular, check coil pilot signal is present. See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Move on to Step 11 1	Supply/earth not present	Restore wiring See See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Move on to Step 11 1	Control signal missing	Check wiring from coil to ECU. If necessary, replace control unit Op 1056F82
11	TIMING CHECK	All OK	Problems encountered	Operation
	Check that the valve gear timing is correctly adjusted Op. Op. 0510A20 TIMING GEAR WITH BELT DRIVE - CHECK - CARRY OUT OPERATION WITH CAM COVER(S) REMOVED AND TAPPETS ADJUSTED	Move on to Step 12 1	Timing not correct	Adjust valve gear timing Op. Op. 1032B10 TOOTHED TIMING BELT - R + R FOR TIMING ADJUSTMENT OR REPLACEMENT
12	CHECK ON CORRECT OPERATION	All OK	Problems encountered	Operation
	Check that the fault is no longer present	End of diagnosis

‹ Prev Gear flashing on the display Next › Engine not running smoothly / (losing power)

Parts & tools for this job For 2003 Alfa Romeo GT

Links open Amazon search results in a new tab. As an Amazon Associate I earn from qualifying purchases.