Engine not running smoothly / (losing power)

Make: Fiat
Model: Doblò Factory Service Manual
Year: 2000–2010
Section: Engine › Engine not running smoothly / (losing power)

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Fault diagnosisEngine not running smoothly / (losing power)

ENGINE NOT RUNNING SMOOTHLY / (LOSING POWER)

Under conditions of constant load and speed, there are intermittent decreases in performance, even prolonged

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	First check: the state of the spark plugs and leads; the condition of the air filter; the condition of the air intake circuit for any obstructions of the catalyzer;	Continue to Step 1	Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10
			Spark plug leads damaged	Replace spark plug leads Op. 5510D14
			Air intake circuit check	Eliminate the problem
			Catalytic converter obstructed	Replace the exhaust manifold Op. 1072C16
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	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	Continue to Step 2	'Fuel system' error appears	See table Z50 MIXTURE STRENGTH ERROR
			'Misfiring' error appears	See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Incoherent parameter	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions under which the fault arises, keeping the diagnostic equipment connected Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	Continue to Step 3	'Fuel system' error appears	See table Z50 MIXTURE STRENGTH ERROR
			'Misfiring' error appears	See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Incoherent parameter	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 Op. 0510C10in the conditions that lead to the anomaly	Continue to Step 4	Insufficient fuel presure: pipes obstructed	Eliminate the obstructions
			Insufficient fuel supply pressure: valve obstructed	Replace the tank cap Op. 1040A40
			Insufficient fuel supply pressure: regulator stuck	Replace pump assembly Op. 1040A70
			Insufficient fuel pump: pump faulty	Replace pump assembly Op. 1040A70
			Fuel pressure insufficient: filter blocked	Replace pump assembly Op. 1040A70
4	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit defective	Replace control unit Op. 1056B82

Under conditions of constant load and speed, there are intermittent decreases in performance, even prolonged

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	First check: the condition of the air filter; the condition of the air intake circuit	Continue to Step 1	Blocked filter	Replace the filter element Op. 1048A14
		Continue to Step 1	Air intake circuit check	Eliminate the problem
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	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	Continue to Step 2	'Fuel system' error appears	Continue according to the instructions for the See table Z50 MIXTURE STRENGTH ERROR
			'Misfiring' error appears	Continue according to the instructions for the See table Z53 MISFIRE ERROR
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Incoherent parameter	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle, reproducing the conditions in which the fault arises, keeping the diagnostic equipment connected. Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	Continue to Step 3	'Fuel system' error appears	Continue according to the instructions for the See table Z50 MIXTURE STRENGTH ERROR
			'Misfiring' error appears	Continue according to the instructions for the See table Z53 MISFIRE ERROR
			Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
			Parameters inconstent. Proceed as	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 [PR.0510C10] in the conditions that lead to the anomaly	Continue to Step 4	Insufficient fuel presure: pipes obstructed	Remove the blockages and replace the pipes if necessary
		Continue to Step 4	Insufficient fuel pump: pump faulty	Replace the fuel pump assembly Op. 1040A70
4	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit defective	Replace control unit Op. 1056A82

Under conditions of constant load and speed, there are intermittent decreases in performance, even prolonged

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	First check: the condition of the air intake circuit for any obstructions in the catalyzer that there is no water in the diesel that there is diesel in the tank, and its quality	Continue to Step 1	Faulty in the air intake circuit	Restore the air intake circuit
			Catalyzer obstructed	Replace the catalyzer Op. 1080B62
			Presence of water or other impurities in the diesel	Eliminate the impurity from the diesel and clean the tank Op. 1040A10
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	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	Continue to Step 2	Error detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Implausible parameters	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle keeping the diagnostic instrument connected Make sure that the conditions in which the problem occurs are reproduced Verify: that there are no faults in the engine management control unit the plausibiilty of the parameters	Continue to Step 3	Error suddenly occurs in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Parameters off the scale	Continue following the instructions for the diagnostic equipment
3	CHECK ON INLET MANIFOLD THROTTLE VALVE	All OK	Problems met	Operation
	Manually check that the throttle valve in the inlet manifold and the pneumatic actuator are working properly	Continue to Step 4	Throttle valve stuck in closed position	Eliminate the cause of the sticking, if necessary replace the valve
			Actuator damaged	Replace the pneumatic actuator
			Pipes blocked	Eliminate the blockage; if necessary replace the pipes
4	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the brake pedal switch is working properly See E2021 BRAKE LIGHTS	Continue to Step 5	Brake pedal does not return	Eliminate the cause of the sticking
			Switch stuck closed	Replace the switch Op. 5550D10
			Wiring short circuited	Eliminate the cause of the problem See E2021 BRAKE LIGHTS
5	CHECK ON EGR VALVE	All OK	Problems met	Operation
	Visually check the operation of the EGR valve, after dismantling it Op. 1080C10	Continue to Step 6	EGR valve jammed open	Replace the EGR valve Op. 1080C10
6	CHECK ON FUEL INJECTORS	All OK	Problems met	Operation
	Check the injectors for leaks and that they are correctly calibrated Op. 1060B10	Continue to Step 7	Incorrect injector calibration	Restore the correct calibration Op. 1060B10
		Continue to Step 7	Faulty injectors	Replace the injectors Op. 1060B10
7	CHECK ON FUEL INJECTION PUMP	All OK	Problems met	Operation
	Check that the fuel injection pump is working correctly	Continue to Step 8	Pump faulty	Replace the pump Op. 1060A10
8	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists: control unit defective	Replace control unit Op. 1060D80

Under conditions of constant load and speed, there are intermittent decreases in performance, even prolonged

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check, in order: that there are no leaks from the fuel system the condition of the air intake circuit for any obstructions in the catalyzer that there is no water in the diesel filter	Continue to Step 1	Fuel leaks	Eliminate the water from the diesel
			Faulty in the air intake circuit	Restore the air intake circuit
			Catalyzer obstructed	Replace the catalyzer
			Water in diesel filter	Clean the tank and replace the filter
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket. Verify: that there are no errors in the control unit the plausibiilty of the parameters	Continue to Step 2	Error detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Implausible parameters	Continue following the instructions for the diagnostic equipment
2	ROAD TEST WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Road test the vehicle keeping the diagnostic instrument connected Make sure that the conditions in which the problem occurs are reproduced Verify: that there are no errors in the control unit the plausibiilty of the parameters	Continue to Step 3	Error suddenly occurs in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Parameters off the scale	Continue following the instructions for the diagnostic equipment
3	CHECK ON BRAKE PEDAL SWITCH	All OK	Problems met	Operation
	Check that the brake pedal switch is working properly See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT	Continue to Step 4	Brake pedal does not return	Eliminate the cause of the sticking
			Switch faulty	Replace the switch
			Wiring short circuited (intermittently)	Eliminate the cause of the problem See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
4	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

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Parts & tools for this job For 2000 Fiat Doblò

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