D05 ENGINE DOES NOT PRODUCE BEST PERFORMANCE - Alfa - 166 - eLearn

3308606 - D05 ENGINE DOES NOT PRODUCE BEST PERFORMANCE

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

1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
		Results of the tests
	Connect diagnostic equipment (Examiner or other instruments) to the diagnostic socket. Verify: that there are no faults in the engine management control unit plausibility of all the parameters (in particular check that the accelerator pedal signal reaches 100%)	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
			Lack of dialogue with the control unit	Restore the connection between the engine management control unit and the diagnostic connector ( See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT )
			The accelerator pedal signal does not reach 100%	Adjust the accelerator pedal travel. After adjustment, if the signal does not reach 100%, replace the potentiometer. Op. 1060G34
2	FUEL FILTER CHECK	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 tank and pipes and replace filter element Op. 1044B20
3	CHECKING AIR CIRCUIT	All OK	Problems met	Operation
	Check, in order: the condition of the air filter the condition and seal of the air supply circuit	Continue to Step 4	Filter dirty or partially blocked	Replace air filter Op. 1048A14
		Continue to Step 4	Circuit component damaged	Replace the component (see Assembly PROCEDURES. 1048A)
4	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the brake pedal switch is working properly (for example, check that the stop lights are working properly)	Continue to Step 5	Brake pedal switch connection faulty	Restore the connections ( See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT )
		Continue to Step 5	Brake pedal switch faulty	Replace the brake pedal switch Op. 5550D10
5	CHECK ON TURBOCHARGER	All OK	Problems met	Operation
	Check the operation of the turbocharger (check condition of impeller, shaft endfloat), carry out turbocharging pressure test: See Test 1064AA Check turbo presure	Continue to Step 6	Turbocharger faulty	Replace turbocharger Op. 1064A10
6	CHECK RETURN LOW PRESSURE	All OK	Problems met	Operation
	Check the pressure between the twin manifold and the return pipe to the tank: See Test 1060A Check low pressure fuel circuit	Continue to Step 7	Pressure over 1 bar: the return circuit to the tank is clogged	Remove any blockages in the return pipe or the cage for the low pressure pump immersed in the tank
7	CHECK ON DELIVERY LOW PRESSURE	All OK	Problems met	Operation
	Check filter between diesel filter and 'radialjet' high pressure pump See Test 1060B Check low pressure fuel circuit	Continue to Step 8	Leaks in circuit	Eliminate fuel leaks from pipes/low pressure circuit connections
			Pressure under 1.8 bar or difference in pressure between Test B and Test A less than 1 bar	Replace valve on diesel filter mounting Op. 1044B16 Replace the fuel pump Op. 1040A70
			Pressure over 3.5 bar	Replace valve on diesel filter mounting Op. 1044B16
8	INJECTOR LEAK TEST	All OK	Problems met	Operation
	Check whether diesel is leaking from the injectors: See Test 1060C Check high pressure fuel circuit	Continue to Step 9	One or more injectors leaking	Replace injector(s) Op. 1060F10
9	HIGH PRESSURE CHECK	All OK	Problems met	Operation
	Check diesel pressure parameter measured with diagnostic instrument: See Test 1060D Check high pressure fuel circuit	Continue to Step 10	Pressure reading below 150 bar	Replace high pressure pump Op. 1060E10
		Continue to Step 10	Leaks in circuit	Eliminate fuel leaks from high pressure circuit pipes/connectors
10	CHECK EXHAUST PIPE	All OK	Problems met	Operation
	Check for blockages in the exhaust pipe	Continue to Step 11	Exhaust pipe blocked	Replace the component involved
11	CHECKING VALVE CLEARANCES	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct. Op. 1036H14	Continue to Step 12	Clearance not correct	Restore the correct valve clearance. Op. 1036H18
12	CHECKING TIMING	All OK	Problems met	Operation
	Check that the engine timing is correct Op. 0510A20	Continue to Step 13	Timing not correct	Restore the correct engine timing Op. 1032B14
13	CHECKING CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 14	Compression values not correct	Restore the correct cylinder compression, for example checking the seal of the cylinders (see OVERHAULING ENGINE, Subassembly 1004)
14	HECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists	Search for the fault starting from another symptom'