18 · Diagnostics

D10 Irregular idle speed

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2002
Section: Engine › D10 Irregular idle speed

‹ Prev D03 Engine working irregularly (sawing)Next › D21 Engine stops on the move

Fault diagnosisD10 Irregular idle speed

D10 Irregular idle speed

Step	Test procedure	Result	Action
0	PRELIMINARY CHECKS First check: the state of the spark plugs and leads; the condition of the air filter the condition of the air intake circuit	OK	Move onto step 1
		Plugs dirty or faulty	Replace the spark plugs Op. 5510D10 End of diagnosis
		Leads faulty	Replace spark plug leads End of diagnosis
		Air filter clogged	Replace the filter element Op. 1048A14 End of diagnosis
		Faulty in the air intake circuit	Restore correct operation of the intake circuit End of diagnosis
1	CHECK WITH DIAGNOSTIC EQUIPMENT Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	OK	Move onto step 2
		'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR End of diagnosis
		Another error detected in the control unit	Continue following the instructions for the diagnostic equipment End of diagnosis
		Incoherent parameter	Continue following the instructions for the diagnostic equipment End of diagnosis
2	CHECK ON IDLE ACTUATOR Check that the system carries out the correct idle learning procedure	OK	Move onto step 3
2		Irregular idle	Carry out the correct idle learning End of diagnosis
3	CHECK ON PETROL VAPOUR RECOVERY SYSTEM Check the condition and seal of the petrol vapour recovery pipes	OK	Move onto step 4
		Air leaks	Renew the correct seal End of diagnosis
		Pipe between filter and intermediate coupling broken	Replace the pipe Op. 1080E61 End of diagnosis
		Pipe between intermediate coupling and solenoid valve 1 Renew the correct seal	Replace the pipe Op. 1080E63 End of diagnosis
4	CHECK ON PETROL VAPOUR RECOVERY SOLENOID Carry out active diagnosis of solenoid	OK	Move onto step 6
4		Faulty solenoid	Move onto step 5
5	CHECK ON SOLENOID ELECTRICAL CIRCUIT Check supply and earth of petrol vapour recovery solenoid Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL	OK	Move onto step 6
		Solenoid valve faulty	Replace the solenoid valve Op. 1080E28 End of diagnosis
		Connections not correct	Restore connections Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL End of diagnosis
6	CHECK ON BRAKE SERVO AND PIPE Check condition of: brake servo vacuum pipes brake servo	OK	Move onto step 7
		Brake servo pipe faulty	Replace the pipe Op. 3330D24 End of diagnosis
		Brake servo faulty	Replace the brake servo/pump assembly Op. 3330D02 End of diagnosis
7	CHECK FUEL PRESSURE Check the fuel supply pressure Op. 0510C10	OK	Move onto step 8
		Insufficient fuel pressure: pipe blocked	Eliminate the blockage; if necessary replace the pipe Op. 1040B30 End of diagnosis
		Fuel pressure insufficient: filter blocked	Replace the pump assembly Op. 1040A70 End of diagnosis
		Insufficient fuel supply pressure: regulator stuck	Replace the pump assembly Op. 1040A70 End of diagnosis
		Insufficient fuel pump: pump faulty	Replace the pump assembly Op. 1040A70 End of diagnosis
8	Check variable valve timing system manifold Carry out active diagnosis of variable valve timing	OK	Move onto step 10
8		Faulty solenoid	Move onto step 9
8	Check variable valve timing system manifold Carry out active diagnosis of variable valve timing	OK	Move onto step 10
8		Faulty solenoid	Move onto step 9
9	CHECK ON TIMING VARIATOR ELECTRICAL CIRCUIT Check power and earth of variable valve timing system solenoid Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL	OK	Move onto step 10
		Timing variator faulty	Replace the phase transformer Op. 1036C40 End of diagnosis
		Connections not correct	Restore connections Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL End of diagnosis
9	CHECK ON TIMING VARIATOR ELECTRICAL CIRCUIT Check power and earth of variable valve timing system solenoid Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL	OK	Move onto step 10
		Timing variator faulty	Replace the phase transformer Op. 1036C40 End of diagnosis
		Connections not correct	Restore connections Wiring diagram E5030 PETROL ENGINES ELECTRONIC CONTROL End of diagnosis
10	CHECKING VARIABLE VALVE TIMING Check the operation of the variable valve timing system by powering the solenoid of the variator directly. There must be a significant change in engine speed (surging or very irregular idle)	OK	Move onto step 11
10		There are no changes in engine speed: timing variator stuck	Replace the phase transformer Op. 1036C40 End of diagnosis
10	CHECKING VARIABLE VALVE TIMING Check the operation of the variable valve timing system by powering the solenoid of the variator directly. There must be a significant change in engine speed (surging or very irregular idle)	OK	Move onto step 11
10		There are no changes in engine speed: timing variator stuck	Replace the phase transformer Op. 1036C40 End of diagnosis
11	TIMING CHECK Check that the timing is correct	OK	Move onto step 12
11	TIMING CHECK Check that the timing is correct	Timing incorrect	Restore the correct timing Op. 1032B10 End of diagnosis
12	CORRECT OPERATION CHECK Check that the fault is no longer present	OK	Incorrect selection of diagnostic procedure
12		The fault persists: control unit defective	Replace control unit Op. 1056B82 Incorrect selection of diagnostic procedure

‹ Prev D03 Engine working irregularly (sawing)Next › D21 Engine stops on the move

Parts & tools for this job For 2000 Alfa Romeo 147

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