Engine does not produce best performance

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2004
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

1.9 JTD 8V

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: the condition of the air intake circuit no faults in the air filter; seal of the diesel pipes; accelerator pedal travel; absence of obstructions in the catalytic converter	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
			Air filter blocked	Replace the filter element Op. 1048A14
			Leaks from the diesel pipes	Eliminate the leaks
			Accelerator pedal travel incomplete	Eliminate the cause of the problem
			Catalyzer obstructed	Replace the catalyzer
			Operation incorrect	Carry out the actuator leak test See Test 1064BC Variable geometry turbocharger actuator leakage test
1	CHECK TURBOCHARGER ADJUSTMENT	All OK	Problems met	Operation
	With the diagnostic equipment, carry out active diagnosis on the turbocharger regulating solenoid Check the operation of the variable geometry control actuator See Test 1064BC Variable geometry turbocharger actuator leakage test	Continue to Step 2	Solenoid not working	Check the continuity of the wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENTand if necessary replace the solenoid
		Continue to Step 2	Actuator does not work correctly	Check the condition of the vacuum circuit and, if necessary, replace the damaged components
2	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 parameters; carry out active diagnosis of E.G.R. solenoid	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
			E.G.R. solenoid not working	Check wiring continuity See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			E.G.R. solenoid not working	Replace the solenoid valve Op. 1080C74
3	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 4	Errors suddenly occur in the control unit	Continue following the instructions for the diagnostic equipment
			Parameters off scale	Continue following the instructions for the diagnostic equipment
			Lack of dialogue with the control unit	Restore the connection between engine management control unit and diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
4	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the brake pedal switch is working properly	Continue to Step 5	Brake pedal does not return	Eliminate the cause of the sticking
			Switch stuck in closed position	Replace the switch Op. 1060G38
			Wiring short circuited	Restore the correct connection
5	CHECK ON TURBOCHARGER	All OK	Problems met	Operation
	Check the operation of the turbocharger See Test 1064BA Check the supercharging pressure	Continue to Step 6	Turbocharger faulty	Replace the turbocharger
6	HIGH PRESSURE CHECK	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check as described in test 1060D that the diesel pressure parameter is correct	Continue to Step 14	Pressure not correct	Continue to Step 7
7	CHECK ON RETURN LOW PRESSURE	All OK	Problems met	Operation
	Check that the pressure in the fuel return pipe to the tank is less than 1 bar See Test 1060A Low return fuel pressure circuit check	Continue to Step 8	Pressure above maximum limit: return pipe to tank blocked	Repair the pipe, if necessary, replace it.
8	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Check that the diesel pressure between filter and pressure pump is between 2 and 3 bar See Test 1060B Low fuel pressure supply circuit check	Continue to Step 14	Pressure below minimum limit or above maximum value	Continue to Step 9
9	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Choke the return pipe and, with the pipe choked, check that the filter outlet pressure remains below 2 bar See Test 1060B Low fuel pressure supply circuit check	Continue to Step 10	Pressure rises to 5 bar: blocked pressure regulation valve on filter support	Replace the valve Op. 1044B16
10	CHECK DELIVERY LOW PRESSURE	All OK	Problems met	Operation
	Check that the difference in pressure upstream and downstream of the filter is less than 1 bar	Continue to Step 11	Difference in pressure greater than 1 bar	Replace the fuel filter cartridge Op. 1044B20
11	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Check that the pressure downstream of the supply pump is over 2.2 bar	Continue to Step 14	Pressure below 2 bar	Continue to Step 12
12	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Measure the difference in pressure between the electric pump outlet and filter inlet, checking that it is less than 0.3 bar	Continue to Step 13	Difference in pressure greater than 0.3 bar	Replace the pipe
13	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Check that the pump supply voltage is 12 V and that the absorbed current is between 2 and 10 amp. See Test 1040AA Check supply voltage and absorption current	Continue to Step 14	Voltage < 12 V	Check electric wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Current > 10 Amp: pump defective	Replace the fuel pump assembly Op. 1040A70
			Current < 2 Amp.: pump blocked	Replace the fuel pump assembly Op. 1040A70and clean the fuel tank
14	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Replace the DRV pressure regulating valve and check that the fault is no longer present		Fault persists	Continue to Step 15
15	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Replace the pressure pump and check that the fault is no longer present		Fault persists	Continue to Step 16
16	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 17	Timing not correct	Restore the correct timing Op. 1032B14
17	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct.	Continue to Step 18	Valve clearance not correct	Adjust the tappets Op. 1036H10
18	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 20	Cylinder compression insufficient	Continue to Step 19
19	CHECKING CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R.R. on head to check the valve seal and check the condition of the cylinders/piston rings	Continue to Step 20	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
20	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists: control unit faulty	Replace control unit Op. 1060G80 Search for the fault starting from another symptom'

1.9 JTD 16V

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: the condition of the air intake circuit no faults in the air filter; seal of the diesel pipes; accelerator pedal travel; absence of obstructions in the catalytic converter	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
			Air filter blocked	Replace the filter element Op. 1048A14
			Leaks from the diesel pipes	Eliminate the leaks
			Accelerator pedal travel incomplete	Eliminate the cause of the problem
			Exhaust system obstructed	Replace the defective system component
1	CHECK TURBOCHARGER ADJUSTMENT	All OK	Problems met	Operation
	With the diagnostic equipment, carry out active diagnosis on the turbocharger regulating solenoid Check the operation of the variable geometry control actuator See Test 1064BC Variable geometry turbocharger actuator leakage test Check the operation of the turbocharger as described in the Test See Test 1064BA Check the supercharging pressure	Continue to Step 2	Solenoid not working	Check the continuity of the wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENTand if necessary replace the solenoid valve (see in Op. 1064A28
			Actuator does not work correctly	Check the condition of the vacuum circuit and, if necessary, replace the damaged components
			Turbocharger faulty	Replace the turbocharger
2	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 parameters; carry out active diagnosis of E.G.R. solenoid	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
			E.G.R. solenoid not working	Check wiring continuity See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			E.G.R. solenoid not working	Replace the solenoid valve Op. 1080C74
3	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 4	Errors suddenly occur in the control unit	Continue following the instructions for the diagnostic equipment
			Parameters off scale	Continue following the instructions for the diagnostic equipment
			Lack of dialogue with the control unit	Restore the connection between engine management control unit and diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
4	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the brake pedal switch is working properly	Continue to Step 5	Brake pedal does not return	Eliminate the cause of the sticking
			Switch stuck in closed position	Replace the switch Op. 1060G38
			Wiring short circuited	Restore the correct connection
5	HIGH PRESSURE CHECK	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check as described in test 1060D that the diesel pressure parameter is correct	Continue to Step 13	Pressure not correct	Continue to Step 6
6	CHECK ON RETURN LOW PRESSURE	All OK	Problems met	Operation
	Check as described in the test 1060A that the pressure in the return pipe to the tank is under 1 bar	Continue to Step 7	Pressure above maximum limit: return pipe to tank blocked	Repair the pipe, if necessary, replace it.
7	CHECK ON RETURN LOW PRESSURE	All OK	Problems met	Operation
	LOW SUPPLY PRESSURE CHECK See Test 1060B Low fuel pressure supply circuit check	Continue to Step 13	Pressure below minimum limit or above maximum value	Continue to Step 8
8	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Choke the return pipe and repeat test 1060B with the pipe choked, checking that the pressure at the filter outlet remains below 2 bar See Test 1060B Low fuel pressure supply circuit check	Continue to Step 9	Pressure rises to 5 bar: blocked pressure regulation valve on filter support	Replace the valve Op. 1044B16
9	CHECK DELIVERY LOW PRESSURE	All OK	Problems met	Operation
	Check that the difference in pressure upstream and downstream of the filter is less than 1 bar	Continue to Step 10	Difference in pressure greater than 1 bar	Replace the fuel filter cartridge Op. 1044B20
10	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Check that the pressure downstream of the supply pump is over 2.2 bar	Continue to Step 13	Pressure below 2 bar	Continue to Step 11
11	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Measure the difference in pressure between the electric pump outlet and filter inlet, checking that it is less than 0.3 bar	Continue to Step 12	Difference in pressure greater than 0.3 bar	Replace the pipe
12	LOW SUPPLY PRESSURE CHECK	All OK	Problems met	Operation
	Check that the pump supply voltage is 12 V and that the absorbed current is between 2 and 10 amp. See Test 1040AA Check supply voltage and absorption current	Continue to Step 13	Voltage < 12 V	Check electric wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Current > 10 Amp: pump defective	Replace the fuel pump assembly Op. 1040A70
			Current < 2 Amp.: pump blocked	Replace the fuel pump assembly Op. 1040A70and clean the fuel tank
13	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Replace the DRV pressure regulating valve and check that the fault is no longer present		Fault persists	Continue to Step 14
14	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Replace the pressure pump and check that the fault is no longer present		Fault persists	Continue to Step 15
15	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 16	Timing not correct	Restore the correct timing Op. 1032B14
16	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct.	Continue to Step 17	Valve clearance not correct	Adjust the tappets Op. 1036H10
17	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 19	Cylinder compression insufficient	Continue to Step 18
19	CHECKING CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R.R. on head to check the valve seal and check the condition of the cylinders/piston rings	Continue to Step 20	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
19	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists

All versions

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/that there is nothing blocking the air flow no obstructions in the exhaust pipe	Continue to Step 1	Air intake circuit fault	Renew the air intake circuit
		Continue to Step 1	Pipe partly obstructed (catalyzer)	Renew/replace pipe
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 detected	Continue according to the instructions for the diagnostic equipment
		Continue to Step 2	Inconsistent parameter	Analyse the factors that have caused this inconsistency
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Carry out a road test 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 and rail pressure setting * injection times * air mass value advances / possible advance reductions for detonation	Continue to Step 3	errors present	Continue according to the instructions for the diagnostic equipment
		Continue to Step 3	Inconsistent parameter	Analyse the factors that have caused this inconsistency
3	LOW FUEL PRESSURE CIRCUIT TEST	All OK	Problems met	Operation
	Check the fuel supply pressure (see [PR.0510C10]) in the conditions in which the fault occurs Op. 0510C10	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove restrictions
			Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
			inconsistent pump supply	Restore the 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
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	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 E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 8	No signal, wiring broken	renew the wiring See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 8	No signal, wiring not broken	replace the engine management control unit
8	CHECK THE VARIABLE VALVE TIMING SOLENOID	All OK	Problems met	Operation
	Carry out active diagnosis of variable valve timing Check the operation of the variable valve timing system by powering the solenoid of the variator directly during idling. There must be a significant variation in engine speed (surging or very irregular idling)	Continue to Step 9	Solenoid not working	Check: actuator resistance condition of wiring control signal from control unit possible actuator mechanical failure
9	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 10	Timing not correct	Restore the correct timing
10	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 12	Cylinder compression insufficient	Continue to Step 11
11	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R/R on head to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 12	Insufficient valve seal	Overhaul the cylinder head
		Continue to Step 12	Cylinders/piston rings worn	Repair the leak
12	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

3.2 V6

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: condition of air filter; the condition of the air intake circuit; no obstructions in the exhaust pipe	Continue to Step 1	Air intake circuit fault	Eliminate the problem, if necessary replacing the filter element Op. 1048A14
		Continue to Step 1	Pipe obstructed	Restore the operation of the exhaust pipe
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 as instructed in the Table See table Z50 MIXTURE STRENGTH 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
	Carry out a road test 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
			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 [PR. 0510C10] in the condition in which the problem occurs	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove restrictions
		Continue to Step 4	Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
4	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 5	Timing not correct	Restore the correct timing
5	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 7	Cylinder compression insufficient	Continue to Step 6
6	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R/R on head to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 7	Insufficient valve seal	Overhaul the cylinder head
		Continue to Step 7	Cylinders/piston rings worn	Repair the leak
7	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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