D10 ENGINE IDLE IRREGULAR - Alfa - 156 - eLearn

3233019 - D10 ENGINE IDLE IRREGULAR

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.)

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 the condition of the spark plugs	Continue to Step 1	Fault in air intake circuit	Restore the correct operation of the intake circuit
		Continue to Step 1	Spark plugs worn, fouled or not the type recommended by the manufacturer	Replace the spark plugs
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 the plausibiilty of the parameters, in particular: accelerator pedal position throttle self-learning target and actual idle speeds rail pressure - rail pressure setting	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Inconsistent parameter	Anaylze the factors that have caused this inconsistency
2	PETROL VAPOUR RECOVERY SYSTEM CHECK	All OK	Problems met	Operation
	Check the condition and the seal of the pipe between the canister solenoid valve and the intake manifold	Continue to Step 3	Air seepage	Restore the correct seal
		Continue to Step 3	Pipe between solenoid valve and manifold damaged	Replace the pipe
3	PETROL VAPOUR RECOVERY SOLENOID VALVE CHECK	All OK	Problems met	Operation
	Carry out active diagnosis of solenoid; check that the air port opens and closes mechanically.	Continue to Step 4	Solenoid not working	Check supply and earth of petrol vapour recovery solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 4	Mechanical failure: solenoid valve remains open	Replace the solenoid valve
4	BRAKE SERVO AND PIPE CHECK	All OK	Problems met	Operation
	Check the condition of the brake servo vacuum pipes; Check the operation of the single-active valve and the brake servo See Test 3330DA Check operation of brake servo vacuum circuit and vacuum unit	Continue to Step 5	Brake servo pipe defective	Replace the pipe
		Continue to Step 5	Brake servo defective	Replace the brake servo/pump assembly
5	CHECK THE VARIABLE VALVE TIMING SOLENOID	All OK	Problems met	Operation
	Carry out active diagnosis of variable valve timing	Continue to Step 8	Solenoid not working	Continue to Step 6
6	CHECK VARIABLE VALVE TIMING ELECTRICAL CIRCUIT	All OK	Problems met	Operation
	Check power and earth of variable valve timing system solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 7	Connections not correct	Restore the connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
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 must be a significant variation in engine speed (surging or very irregular idling)	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 sealCheck 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. 1082B80