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: the condition of air filter the condition of the air intake circuit no obstructions in the exhaust pipe	Continue to Step 1	Air intake circuit fault	Eliminate the problem, if necessary replacing the filter element Op. 1048A14
		Continue to Step 1	Pipe obstructed	Restore the operation of the exhaust 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	'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Inconsistent parameter	Continue following the instructions for the diagnostic equipment
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; plausibility of all the parameters	Continue to Step 3	'Supply system' error detected	See table Z50 MIXTURE STRENGTH ERROR
			Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
			Parameters inconsistent	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems met	Operation
	Road test the vehicle and check the fuel supply pressure in the conditions that lead to the anomaly Op. 0510C10	Continue to Step 4	Insufficient fuel pressure: pipes obstructed	Remove restrictions
		Continue to Step 4	Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
4	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 5	Timing not correct	Restore the correct timing
5	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 7	Cylinder compression insufficient	Continue to Step 6
6	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 7	Insufficient valve seal	Overhaul the cylinder head
		Continue to Step 7	Cylinders/piston rings worn	Repair the leak
7	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