Engine does not produce best performance

Make: Alfa Romeo
Model: GT Factory Service Manual
Year: 2003–2010
Section: Engine › Engine does not produce best performance

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Fault diagnosisEngine does not produce best performance

ENGINE DOES NOT PRODUCE BEST PERFORMANCE

1.8 T.SPARK

Engine judders when car is in motion and is not efficient.

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Results of the tests
	First, check: status of spark plugs and leads; complete accelerator pedal travel; condition of the air filter; the condition of the air intake circuit; no obstructions at the catalyzer	Move on to Step 1	Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10 SPARK PLUGS - R+R
			Leads damaged	Replace spark plug leads
			Accelerator pedal travel insufficient	Restore the pedal travel
			Air intake circuit faulty	Eliminate the fault
			Catalytic converter obstructed	Replace the exhaust manifold Op. 1072C12 EXHAUST MANIFOLD - 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	"Fuel system" error detected	Continue following the instructions 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	"Fuel system" error detected	Continue following the instructions in the Table Z50 ERRORE TITOLO MISCELA
			The sudden onset of another error is detected	Continue following the instructions for the diagnostic equipment
			Parameters not consistent	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems encountered	Operation
	Carry out a road test and check the fuel supply pressure in the conditions in which the problem occurs Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE	Move on to Step 4	Fuel pressure too low: pipes obstructed	Eliminate the constrictions
			Fuel pressure too low: valve obstructed	Replace the fuel cap Op. 1040A40 PLUG FOR FUEL FILLER PIPE - R + R
			Fuel pressure too low: regulator blocked	Replace the fuel pump assembly Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
			Fuel pressure too low: pump defective	Replace the fuel pump assembly Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
			Fuel pressure too low: filter blocked	Replace the fuel pump assembly Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	PHASE TRANSFORMER SOLENOID VALVE CHECK	All OK	Problems encountered	Operation
	Carry out active diagnosis of the variable valve timing solenoid valve	Move on to Step 6	Solenoid valve not working	Move on to Step 5
5	PHASE TRANSFORMER ELECTRICAL CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check the supply and earth for the variable valve timing solenoid valve See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Move on to Step 6	Phase transformer faulty	Replace the phase transformer Op. 1036C40 TIMING VARIATOR ON INLET CAMSHAFT IN CYLINDER HEAD R + R WITH SHAFT REMOVED
		Move on to Step 6	Connections not correct	Repair the connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
6	PHASE TRANSFORMER CHECK	All OK	Problems encountered	Operation
	Check the operation of the vvt (hydraulic actuator) by carrying out Test 1056OA See Test 1056 PETROL INJECTION SYSTEM	Move on to Step 7	There are no speed variations: phase transformer stuck	Replace the phase transformer Op. 1036C40 TIMING VARIATOR ON INLET CAMSHAFT IN CYLINDER HEAD R + R WITH SHAFT REMOVED
7	TIMING CHECK	All OK	Problems encountered	Operation
	Check that the valve gear timing is correct	Move on to Step 8	Valve gear timing not correct	Restore the correct valve gear timing Op. 1032B10 TOOTHED TIMING BELT - R + R FOR TIMING ADJUSTMENT OR REPLACEMENT
8	CYLINDER COMPRESSION CHECK	All OK	Problems encountered	Operation
	Carry out the cylinder compression check Op. 0510A10 CYLINDER COMPRESSION - CHECK FOR LOOSE SPARK PLUGS OR INJECTORS	Move on to Step 10	Cylinder compression insufficient	Move on to Step 9
9	VALVE SEAL CHECK	All OK	Problems encountered	Operation
	R/R head for valve leakage test Check condition of cylinders/piston rings	Move on to Step 10	Valve seal insufficient	Overhaul the head Op. 1016E10 SINGLE CYLINDER HEAD, REMOVED - OVERHAUL
		Move on to Step 10	Cylinders/piston rings worn	Restore the seal
10	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.

3.2 V6

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Results of the tests
	First, check: If relevant service information is available Condition of air intake circuit/lack of obstructions to the air passage; That there are no obstructions in the exhaust pipe	Move on to Step 1 1	Air intake circuit faulty	Restore intake circuit
		Move on to Step 1 1	Pipe partly obstructed (catalytic converter)	Repair/replace piping
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	Error detected	Continue as instructed by the diagnostic equipment
		Move on to Step 2 1	Parameter not consistent	Analyse the factors that give rise to this inconsistency
2	ROAD TEST USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Carry out a road test keeping the diagnostic equipment connected. Check: That there are no faults in the engine management control unit; Parameter plausibility, particularly: Rail Pressure and rail pressure setting Injection times Air mass Advances/possible advance reduction for knock	Move on to Step 3 1	Presence of errors	Continue as instructed by the diagnostic equipment
		Move on to Step 3 1	Parameter not consistent	Analyse the factors that give rise to this inconsistency
3	FUEL LOW PRESSURE CIRCUIT TEST	All OK	Problems encountered	Operation
	Check the fuel supply pressure Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE under the conditions in which the fault occurs	Move on to Step 4 1	Fuel pressure too low: pipes obstructed	Eliminate the constrictions
			Fuel pressure too low: pump defective	Replace the pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
			Pump supply discontinuous	Restore pump supply circuit
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	CHECK PRESSURE REGULATOR	All OK	Problems encountered	Operation
	Check the operation of the pressure regulator	Move on to Step 6 1	Pressure regulator fault	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	PHASE TRANSFORMER SOLENOID VALVE CHECK	All OK	Problems encountered	Operation
	Carry out the active diagnosis of the phase transformer solenoid valve Check the operation of the phase transformer supplying the phase transformer solenoid avlve directly whilst idling The engine speed should vary considerably (very irregular idling)	Move on to Step 9 1	Solenoid valve not working	Check: actuator resistance, wiring condition, control signal from control unit, actuator mechanical lock
9	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 10 1	Valve gear timing not correct	Restore the correct valve gear timing Op. Op. 1032B10 TOOTHED TIMING BELT - R + R FOR TIMING ADJUSTMENT OR REPLACEMENT
10	CYLINDER COMPRESSION CHECK	All OK	Problems encountered	Operation
	Carry out the cylinder compression check Op. Op. 0510A10 CYLINDER COMPRESSION - CHECK FOR LOOSE SPARK PLUGS OR INJECTORS	Move on to Step 12 1	Cylinder compression insufficient	Move on to Step 11 1
11	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems encountered	Operation
	- Carry out R/R head [PR_1016C10] to test valve leakage Check condition of cylinders/piston rings	Move on to Step 12 1	Valve seal insufficient	Overhaul the cylinder head Op. Op. 1016E10 SINGLE CYLINDER HEAD, REMOVED - OVERHAUL
		Move on to Step 12 1	Cylinders/piston rings worn	Restore the seal
12	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. 1056F82
		Results of the tests
0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
	First, check: Condition of the air filter; Condition of the air intake circuit; That there are no obstructions in the exhaust pipe	Move on to Step 1 1	Air intake circuit faulty	Eliminate the problem, if necessary, replace the filter element Op. Op. 1048A14 AIR CLEANER FILTERING ELEMENT - REPLACE.
		Move on to Step 1 1	Pipe obstructed	Restore the operation of the exhaust pipes
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 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	"Fuel system" error detected	Proceed as instructed in the See table See table Z50 MIXTURE STRENGTH ERROR
			The sudden onset of another error is detected	Continue following the instructions for the diagnostic equipment
			Parameters not consistent	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems encountered	Operation
	Carry out a road test and check the fuel supply pressure Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE under the conditions in which the fault occurs	Move on to Step 4 1	Fuel pressure too low: pipes obstructed	Eliminate the constrictions
		Move on to Step 4 1	Fuel pressure too low: pump defective	Replace the pump assembly Op. Op. 1040A70 SUBMERGED PUMP ASSEMBLY COMPLETE WITH LEVEL GUAGE CONTROL - R + R
4	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 5 1	Valve gear timing not correct	Restore the correct valve gear timing Op. Op. 1032B10 TOOTHED TIMING BELT - R + R FOR TIMING ADJUSTMENT OR REPLACEMENT
5	CYLINDER COMPRESSION CHECK	All OK	Problems encountered	Operation
	Carry out the cylinder compression check Op. Op. 0510A10 CYLINDER COMPRESSION - CHECK FOR LOOSE SPARK PLUGS OR INJECTORS	Move on to Step 7 1	Cylinder compression insufficient	Move on to Step 6 1
6	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems encountered	Operation
	- Carry out R/R head [PR_1016C10] to test valve leakage Check condition of cylinders/piston rings	Move on to Step 7 1	Valve seal insufficient	Overhaul the cylinder head Op. Op. 1016E10 SINGLE CYLINDER HEAD, REMOVED - OVERHAUL
		Move on to Step 7 1	Cylinders/piston rings worn	Restore the seal
7	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

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