23 · Diagnostics

Engine idle irregular

Make: Alfa Romeo
Model: 159 Factory Service Manual
Year: 2005–2011
Section: Engine › Engine idle irregular

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Fault diagnosisEngine idle irregular

ENGINE IDLE IRREGULAR

1.9 JTD 8V, 1.9 JTD 16V, 2.4 JTD 20V

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check: the condition of the air intake circuit condition and correct operation of the air filter	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
		Continue to Step 1	Air filter blocked	Replace the filter element Op. 1048A14
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 errors in the control unit plausibility of all the parameters carry out active diagnosis of E.G.R. solenoid	Continue to Step 2	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 engine management control unit and diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Solenoid not working	Check the continuity of the wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT and if necessary replace the solenoid Op. 1080C74
2	CHECK ON FUEL FILTER	All OK	Problems met	Operation
	Check the operation of the fuel filter	Continue to Step 3	Presence of water, petrol, paraffin or dirt detected	Clean the tank and pipes and replace the diesel filter cartridge Op. 1044B20
3	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 5	Cylinder compression insufficient	Continue to Step 4
4	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 5	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
7	TIMING VARIATOR CHECK	All OK	Problems met	Operation
	Check the operation of the variable valve timing system by powering the solenoid of the variator directly. There should be a considerable variation in the engine speed (very irregular idling or surging).	Continue to Step 8	No speed changes: variable valve timing stuck	Replace the phase transformer Op. 1036C40
8	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 9	Timing not correct	Restore the correct timing
9	CHECK ON INJECTORS	All OK	Problems met	Operation
	Check the condition of the injectors, in particular make sure that there is no reduced fluxing	Continue to Step 10	Injector faulty	Replace injector
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

1.9 JTS, 2.2 JTS, 3.2 JTS

The engine does not run smoothly whilst idling. If this condition is serious, the engine or the vehicle may shudder. The engine idle speed may vary. Any condition may be serious enough to cause the engine to cut out.

0	PRELIMINARY CHECKS	All OK	Problems encountered	Operation
	Check that the MIL warning light is on before starting and that it goes out once the engine has been started. Also check that no accessories have been fitted in the after-market	Move on to Step 1	The MIL warning lights 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 light remains on with the engine started	Continue as instructed in the See table K101 MIL WARNING LIGHT STAYS ON (ENGINE STARTS)
			There are accessories 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 electrical connections for the engine management control unit are correct See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT In particular, check that: - the earth is correctly connected - 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	Connection 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	AIR INTAKE CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check there are no faults in the air intake circuit. In particular, check: - that the air filter is not blocked or fitted incorrectly - that the air intake circuit does not have any irregular constrictions, leaks or is fitted incorrectly	Move on to Step 4	Air filter blocked	Replace the filter element Op. 1048A14 AIR CLEANER FILTER ELEMENT - REPLACE.
			Irregular component	Replace the faulty component Op. 1048 ENGINE AIR SUPPLY CIRCUIT
			Component incorrectly positioned	Refit the component correctly Op. 1048 ENGINE AIR SUPPLY CIRCUIT
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	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 are no impurities such as water, alcohol or particles in suspension in the fuel by carrying out the test See T FUEL QUALITY CHECK	Move on to Step 6	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	Faults present	The operation to solve the problem is described in the actual test
7	THROTTLE CASING ERRORS CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that error P0505 is not present	Move on to Step 8	Error P0505 is present	Continue as described by the diagnostic equipment
8	DETNATION 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 9	One or more of the errors indicated is present	Continue as described by the diagnostic equipment
9	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 any 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 10	One of the coils is not fitted correctly	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
10	SPARK PLUGS CHECK	All OK	Problems encountered	Operation
	Remove the spark plugs Op. 5510D10 SPARK PLUGS - R+R and check that they are no signs of faults, following the instructions in the test See T SPARK PLUG STATE CHECK	Move on to Step 11	Faults present	The operation to solve the problem is described in the actual test
11	RPM SENSOR CHECK	All OK	Problems encountered	Operation
	Check that the resistance value of the rpm sensor in all temperature ranges is between 700 and 1200 Ohm	Move on to Step 12	Resistance values outside of the range	Change the rpm sensor Op. 5510C26 ENGINE RPM SENSOR - R+R
12	PHASE TRANSFORMER ERRORS CHECK	All OK	Problems encountered	Operation
	Connect the diagnostic equipment and check that none of the following errors is present: P0011, P0014, P0021, P0024	Move on to Step 13	One or more of the errors indicated is present	Continue as described by the diagnostic equipment
13	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 15	Cylinder compression insufficient	Move on to Step 14
14	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 15	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
15	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 16	Valve gear timing not correct	Restore the correct valve gear timing
16	EXHAUST SYSTEM CHECK	All OK	Problems encountered	Operation
	Check that the exhaust circuit is not leaking, there are no loose connections, constrictions, deformations or damage	Move on to Step 17	Faults present	Restore the correct fastening of the problem components. Replace them if necessary
17	ENGINE FASTENINGS CHECK	All OK	Problems encountered	Operation
	Check that the engine fastenings are not faulty and are tightened to the recommended torque	Move on to Step 18	There are faults in the fastenings at the supports, mountings or reaction rods	Restore the correct fastening of the problem components. Replace them if necessary
18	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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