23 · Diagnostics

Engine knock

Make: Alfa Romeo
Model: Brera and Spider Factory Service Manual
Year: 2005–2010
Section: Noise / vibrations › Engine knock

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Fault diagnosisEngine knock

ENGINE KNOCK

2.2 JTS

There is slight knocking that usually gets worse during acceleration. The engine produces a dry noise typical of metallic knocking which changes when the throttle opens.

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Test results
	Check that the MIL warning light is on before starting and goes out once the engine has been started up. Also check that no accessories have been fitted in the after-market.	Move on to Step 1	The MIL warning light does not come on when the key is inserted	Continue as instructed in the See table K100 MIL WARNING LIGHT NOT WORKING (REMAINS OFF BEFORE STARTING)
			The MIL warning remains on with the engine started	Continue as instructed in the See table K101 MIL WARNING LIGHT STAYS ON (ENGINE STARTS)
			There are accessories present that have been fitted in the after-market	Check that these accessories have been fitted correctly
1	CONTROL UNIT ELECTRICAL CONNECTIONS CHECK	All OK	Problems encountered	Operation
	Check that the engine management control unit electrical connections are correct See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT In particular, check that: - the earth is connected correctly - the resistance between the control unit See M010 ENGINE MANAGEMENT ECU and the battery negative See A001 BATTERY is less than 0.5 Ohm	Move on to Step 2	Connections to earth incorrect	Restore the correct connections
		Move on to Step 2	Resistance to battery negative more than 0.5 Ohm	Restore the correct connections
2	CONTROL UNIT FASTENING CHECK	All OK	Problems encountered	Operation
	Check that the control unit is correctly fastened in its housing Op. 1056F82 CONTROL UNIT SINGLE OF INJECTION IGNITION SYSTEM R R	Move on to Step 3	Control unit fastening incorrect	Renew the correct fastening of the control unit Op. 1056F82 CONTROL UNIT SINGLE OF INJECTION IGNITION SYSTEM R R
3	ERRORS IN CONTROL UNIT CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that there are no errors present in the control unit	Move on to Step 4	There are errors present in the control unit	Continue as described by the diagnostic equipment
4	FUEL FEED CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check there are no faults in the fuel supply circuit by performing the See Test 1040OA FUEL SUPPLY CIRCUIT CHECK	Move on to Step 5	There are faults present	The operation to solve the problem is described in the actual test
5	CHECK FOR THE PRESENCE OF IMPURITIES IN THE FUEL	All OK	Problems encountered	Operation
	Check that there is no water, alcohol or particles in suspension in the fuel by carrying out the See T FUEL QUALITY CHECK	Move on to Step 6	There are faults present	The operation to solve the problem is described in the actual test
6	INJECTOR CHECK	All OK	Problems encountered	Operation
	Check that the injectors are not stuck shut or not perfectly closed by carrying out the See Test 1056BA INJECTOR OPERATION CHECK	Move on to Step 7	There are faults present	The operation to solve the problem is described in the actual test
7	DETONATION SENSOR ERRORS CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that none of the following errors is present: P0325, P0330	Move on to Step 8	One or more of the errors indicated is present	Continue as described by the diagnostic equipment
8	IGNITION COIL CHECK	All OK	Problems encountered	Operation
	Check that the ignition coils are correctly fitted in their seats. Also check that they do not show signs of corrosion or dampness. Lastly, check that the ignition coils are working properly, by carrying out the test See Test 5510CC IGNITION COIL CHECK	Move on to Step 9	One of the coils is not correctly fitted	Refit the coil correctly Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils shows signs of corrosion/dampness	Replace the coil Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils is not working properly	The operation to solve the problem is described in the actual test
9	OVERHEATING CHECK	All OK	Problems encountered	Operation
	Check the following, in order: - that there are no obvious signs of engine overheating. - that there is sufficient engine coolant of the correct type. - that there are no coolant leaks - that the radiator is correctly fitted and there are no obstructions preventing the flow of air through the structure	Move on to Step 10	There are signs of engine overheating	Continue as instructed in the See table K026 ENGINE COOLANT OVERHEATING WARNING LIGHT NOT WORKING
			Coolant fluid level insufficient	Top up the engine coolant Op. 0010T21 ENGINE COOLANT - CHECK DENSITY AND CHANGE, IF NECESSARY
			Incorrect type of coolant	Change the coolant Op. 0010T20 ENGINE COOLANT - CHANGE
			Coolant leaks	Continue as instructed in the See table X10 ENGINE COOLANT LEAKS
			Radiator fitted incorrectly or with obvious signs of the air flow obstructed	Restore the correct fitting of the components. Replace the faulty components, if necessary
10	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 12	Cylinder compression insufficient	Move on to Step 11
11	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems encountered	Operation
	R/R head for valve leakage test Op. 1016C10 SINGLE CYLINDER HEAD - R.R. AND REPLACE GASKET Check condition of cylinders/piston rings	Move on to Step 12	Valve seal insufficient	Overhaul the head Op. 1016E10 SINGLE CYLINDER HEAD, REMOVED - OVERHAUL
			Cylinders/piston rings worn	Restore the seal
			Cylinder head/cylinder block-crankcase matching faulty	Restore correct matching
12	TIMING CHECK	All OK	Problems encountered	Operation
	Check that the valve gear timing is correct Op. 0510A20 TIMING GEAR WITH BELT DRIVE - CHECK - CARRY OUT OPERATION WITH CAM COVER(S) REMOVED AND TAPPETS ADJUSTED AND CRANKSHAFT PULLEY DETACHED (IF NECESSARY)	Move on to Step 13	Valve gear timing not correct	Restore the correct valve gear timing
13	CHECK ON CORRECT OPERATION	All OK	Problems encountered	Operation
	Check the fault has disappeared	End of diagnosis	The fault persists	Contact the Technical Expert for further information on the problem

3.2 JTS

There is slight knocking that usually gets worse during acceleration. The engine produces a dry noise typical of metallic knocking which changes when the throttle opens.

Make sure that the knocking is not noticeable when the road surface changes. The latter can cause a change in the engine torque transmitted to the rear wheels which could also lead to engine detonation.

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
		Test results
	Check that the MIL warning light is on before starting and that once the engine is started up it goes out. Also check that no accessories have been fitted in the after-market	Move on to Step 1	The MIL warning light does not come on when the key is inserted	Continue as instructed in the See table K100 MIL WARNING LIGHT NOT WORKING (REMAINS OFF BEFORE STARTING)
			The MIL warning remains on with the engine started	Continue as instructed in the See table K101 MIL WARNING LIGHT STAYS ON (ENGINE STARTS)
			There are accessories present that have been fitted in the after-market	Check that these accessories have been fitted correctly
1	CONTROL UNIT ELECTRICAL CONNECTIONS CHECK	All OK	Problems encountered	Operation
	Check that the engine management control unit electrical connections are correct See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT In particular, check that: - the earth is connected correctly - the resistance between the control unit See M010 ENGINE MANAGEMENT ECU and the battery negative See A001 BATTERY is less than 0.5 Ohm	Move on to Step 2	Connections to earth incorrect	Restore the correct connections
		Move on to Step 2	Resistance to battery negative more than 0.5 Ohm	Restore the correct connections
2	CONTROL UNIT FASTENING CHECK	All OK	Problems encountered	Operation
	Check that the control unit is correctly fastened in its housing Op. 1056F82 CONTROL UNIT SINGLE OF INJECTION IGNITION SYSTEM R R	Move on to Step 3	Control unit fastening incorrect	Renew the correct fastening of the control unit Op. 1056F82 CONTROL UNIT SINGLE OF INJECTION IGNITION SYSTEM R R
3	ERRORS IN CONTROL UNIT CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that there are no errors present in the control unit	Move on to Step 4	There are errors present in the control unit	Continue as described by the diagnostic equipment
4	FUEL FEED CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check there are no faults in the fuel supply circuit by performing the See Test 1040OA FUEL SUPPLY CIRCUIT CHECK	Move on to Step 5	There are faults present	The operation to solve the problem is described in the actual test
5	CHECK FOR THE PRESENCE OF IMPURITIES IN THE FUEL	All OK	Problems encountered	Operation
	Check that there is no water, alcohol or particles in suspension in the fuel by carrying out the See T FUEL QUALITY CHECK	Move on to Step 6	There are faults present	The operation to solve the problem is described in the actual test
6	INJECTOR CHECK	All OK	Problems encountered	Operation
	Check that the injectors are not stuck shut or not perfectly closed by carrying out the See Test 1056BA INJECTOR OPERATION CHECK	Move on to Step 7	There are faults present	The operation to solve the problem is described in the actual test
7	DETONATION SENSOR ERRORS CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that none of the following errors is present: P0325, P0330	Move on to Step 8	One or more of the errors indicated is present	Continue as described by the diagnostic equipment
8	IGNITION COIL CHECK	All OK	Problems encountered	Operation
	Check that the ignition coils are correctly fitted in their seats. Also check that they do not show signs of corrosion or dampness. Lastly, check that the ignition coils are working properly, by carrying out the See Test 5510CC IGNITION COIL CHECK	Move on to Step 9	One of the coils on the left cylinder head is not fitted correctly	Refit the coil correctly Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils on the right cylinder head is not fitted correctly	Refit the coil correctly Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils on the left cylinder head shows signs of corrosion/dampness	Replace the coil Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils on the right cylinder head shows signs of corrosion/dampness	Replace the coil Op. 5510C14 IGNITION COIL/S - R.R.
			One of the coils is not working properly	The operation to solve the problem is described in the actual test
9	OVERHEATING CHECK	All OK	Problems encountered	Operation
	Check the following, in order: - that there are no obvious signs of engine overheating. - that there is sufficient engine coolant of the correct type. - that there are no coolant leaks - that the radiator is correctly fitted and there are no obstructions preventing the flow of air through the structure	Move on to Step 10	There are signs of engine overheating	Continue as instructed in the See table K026 ENGINE COOLANT OVERHEATING WARNING LIGHT NOT WORKING
			Coolant fluid level insufficient	Top up the engine coolant Op. 0010T21 ENGINE COOLANT - CHECK DENSITY AND CHANGE, IF NECESSARY
			Incorrect type of coolant	Change the coolant Op. 0010T20 ENGINE COOLANT - CHANGE
			Coolant leaks	Continue as instructed in the See table X10 ENGINE COOLANT LEAKS
			Radiator fitted incorrectly or with obvious signs of the air flow obstructed	Restore the correct fitting of the components. Replace the faulty components, if necessary
10	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 12	Cylinder compression insufficient	Move on to Step 11
11	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems encountered	Operation
	R/R head for valve leakage test Op. 1016D10 CYLINDER HEAD – R.R. AND REPLACE GASKETS Check condition of cylinders/piston rings	Move on to Step 12	Valve seal insufficient	Overhaul the heads Op. 1016E20 CYLINDER HEAD (ONE), LEFT OR RIGHT, REMOVED - OVERHAUL
			Cylinders/piston rings worn	Restore the seal
			Cylinder head/cylinder block-crankcase matching faulty	Restore correct matching
12	TIMING CHECK	All OK	Problems encountered	Operation
	Check that the valve gear timing is correct Op. 0510A20 TIMING GEAR WITH BELT DRIVE - CHECK - CARRY OUT OPERATION WITH CAM COVER(S) REMOVED AND TAPPETS ADJUSTED AND CRANKSHAFT PULLEY DETACHED (IF NECESSARY)	Move on to Step 13	Valve gear timing not correct	Restore the correct valve gear timing
13	CHECK ON CORRECT OPERATION	All OK	Problems encountered	Operation
	Check the fault has disappeared	End of diagnosis	The fault persists	Contact the Technical Expert for further information on the problem

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