D05 ENGINE DOES NOT PRODUCE BEST PERFORMANCE - Alfa - 156 - eLearn

3233018 - D05 ENGINE DOES NOT PRODUCE BEST PERFORMANCE

The engine runs smoothly at medium-low speeds, but does not reach iits usual maximum performance (both in terms of speed and acceleration)

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	There are errors	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 Op. 0510C10 ) in the conditions in which the fault occurs	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	Renew 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 engine management control unit
8	CHECK THE VARIABLE VALVE TIMING SOLENOID	All OK	Problems met	Operation
	Carry out active diagnosis of variable valve timingCheck 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 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