Engine does not produce best performance

Make: Fiat
Model: Doblò Factory Service Manual
Year: 2000–2010
Section: Engine › Engine does not produce best performance

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Fault diagnosisEngine does not produce best performance

ENGINE DOES NOT PRODUCE BEST PERFORMANCE

The engine runs smoothly at medium-low speeds, but does not reach its 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 state of the spark plugs and leads; full accelerator pedal travel the condition of air filter the condition of the air intake circuit absence of obstructions in the catalytic converter	Continue to Step 1	Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10
			Cables damaged	Replace spark plug leads Op. 5510D14
			Insufficient accelerator pedal travel	Restore pedal travel
			Air intake circuit fault	Eliminate the problem
			Catalyzer 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. 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
	Road test the vehicle, reproducing the conditions in which the fault arises, 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
			Inconsistent 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 pressure: pipes obstructed	Remove restrictions
			Insufficient fuel pressure: valve obstructed	Replace the tank cap Op. 1040A40
			Insufficient fuel pressure: regulator out of calibration	Replace the pump assembly Op. 1040A70
			Low fuel pressure: defective pump	Replace fuel pump assembly Op. 1040A70
			Low fuel pressure: clogged filter	Replace fuel pump assembly Op. 1040A70
4	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct Op. 0510A20	Continue to Step 5	Timing not correct	Restore the correct timing Op. 1032B10
1.2 8v Climatizzatore	Check that the timing is correct Op. 0510A20	Continue to Step 5	Timing not correct	Restore the correct timing Op. 1032B14
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 Op. 1016C10to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 7	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
		Continue to Step 7	Cylinders/piston rings worn	Repair the leak
1.2 8v Climatizzatore	Carry out R/R on head Op. 1016C11to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 7	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
1.2 8v Climatizzatore		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

The engine runs smoothly at medium-low speeds, but does not reach its 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
			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
			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 Op. 0510C10in the conditions that lead to the anomaly	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 6	Cylinder compression insufficient	Continue to Step 12
6	CHECK ON CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R/R on head to check the valve seal Check 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

The engine runs smoothly at medium-low speeds, but does not reach its 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 the air intake circuit no faults in the air filter; seal of the diesel pipes; accelerator pedal travel; that there are no obstructions in the catalyzer that there is diesel in the tank, and its quality	Continue to Step 1	Air intake circuit fault	Renew the air intake circuit
			Air filter blocked	Replace the filter element Op. 1048A14
			Leak from diesel pipes	stop the leak
			Accelerator pedal travel incomplete	Eliminate the cause of the problem
			Catalyzer obstructed	Replace the catalyzer Op. 1080B62
			Diesel of poor quality	Clean the tank Op. 1040A10and fill with diesel of superior quality
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	Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Inconsistent 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. check that there are no faults in the engine management control unit; plausibility of all the parameters	Continue to Step 3	Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
		Continue to Step 3	Inconsistent parameter	Continue following the instructions for the diagnostic equipment
3	CHECK ON INLET MANIFOLD BUTTERFLY 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	Butterfly 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 pipe
4	DIESEL FILTER CHECK	All OK	Problems met	Operation
	Check that the diesel filter is not blocked	Continue to Step 5	Diesel filter blocked	Replace the filter Op. 1044B10
5	CHECK ON FUEL INJECTION PUMP TIMING	All OK	Problems met	Operation
	Check the timing of the fuel injection pump Op. 1060A20	Continue to Step 6	Fuel injection pump timing set incorrectly	Restore the correct timing Op. 1060A20
6	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 7	Brake pedal does not return	Eliminate the cause of the sticking
			Switch stuck in closed position	Replace the switch Op. 5550D10
			Wiring short circuited	Eliminate the cause of the problem See E2021 BRAKE LIGHTS
1.9 DIESEL Climatizzatore	Carry out R/R on head Op. 1016C11to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 7	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
1.9 DIESEL Climatizzatore		Continue to Step 7	Cylinders/piston rings worn	Repair the leak
7	CHECK EGR VALVE	All OK	Problems met	Operation
	Visually check the operation of the EGR valve, after dismantling it Op. 1080C10	Continue to Step 8	EGR valve stuck in open position	Replace the EGR valve Op. 1080C10
8	CHECK ON INJECTORS	All OK	Problems met	Operation
	Check the injectors for leaks and that they are correctly calibrated Op. 1060B10	Continue to Step 9	Incorrect injector calibration	Restore the correct calibration Op. 1060B10
		Continue to Step 9	Faulty injectors	Replace the injectors Op. 1060B10
9	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct. Op. 1036H14	Continue to Step 10	Valve clearance not correct	Adjust the tappets Op. 1036H14
10	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 11	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 Op. 1016C10to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 12	Insufficient valve seal	Overhaul the cylinder head Op. 1016C10
12	CHECK ON FUEL INJECTION PUMP	All OK	Problems met	Operation
	Check that the fuel injection pump is working correctly	Continue to Step 13	Pump faulty	Replace the pump Op. 1060A10
13	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. 1080D80

BIPOWER

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

0	PRELIMINARY CHECKS:	All OK	Problems met	Operation
		Results of the tests
	The state of the spark plugs and leads The condition of the air intake circuit For a possible obstruction of the catalyzer and other exhaust pipes For any obstacles to the complete accelerator pedal travel	Continue to Step 1	Spark plugs worn	Replace the spark plugs
			Spark plug leads worn or damaged	Replace the spark plug leads
			Air intake circuit fault	Eliminate the problem, if necessary replacing the filter element
			Catalyzer/exhaust pipes obstructed	Restore the operation of the exhaust pipe
			Accelerator cable faulty	Restore the operation of the accelerator cable
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the Examiner diagnostic equipment to the diagnostic connector and check the following at the METHANE engine management control unit: in errors ambient: that there are no faults in the METHANE engine management control unit in parameters ambient: the plausibility of all the parameters.	Continue to Step 2	An error is detected in the control unit	Continue according to the instructions for the diagnostic equipment
2	ACCELERATOR CHECK	All OK	Problems met	Operation
	Check that the accelerator cable is working properly in particular, check: Condition of the cable Correct sliding of the cable in the sheath Correct fastening of the sheath	Continue to Step 3	Accelerator cable faulty	Renew the accelerator cable
3	METHANE PRESSURE CHECK	All OK	Problems met	Operation
	Using the Examiner diagnostic equipment connected to the diagnostic connector, check the following at the METHANE engine management control unit: in parameters ambient: the METHANE high pressure carrying out the test See Test 1058A Check on methane pressure in high pressure circuit Check the methane low pressure carrying out the test See Test 1044EB Check on methane low pressure circuit Check the pressure sensor carrying out the test See Test 1058AA Check on operation of Methane pressure sensor	Continue to Step 4	Methane injection quantity incorrect	Replace the methane injectors
			Pressure incorrect because methane pressure reduction unit is stuck	Replace the pressure reduction unit Op. 1044E10
			Pressure incorrect because methane pressure sensor is defective	Replace the pressure sensor Op. 1044E16
			Pressure incorrect due to methane leaks from the system	Eliminate the leaks
4	HIGH PRESSURE CIRCUIT LEAKAGE TEST	All OK	Problems met	Operation
	Check the high pressure circuit for leaks by carrying out the test See Test 1058C Methane high pressure circuit leakage test	Continue to Step 5	The system is not sealed	Renew the seal
5	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 6	Timing not correct	Restore the correct engine timing
6	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 7	Compression values not correct	Continue to Step 7
7	CHECK ON CAUSE OF INSUFFICIENT CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out R/R on head to check the valve seal Check the condition of the cylinders/piston rings	Continue to Step 8	Insufficient valve seal	Overhaul the cylinder head
		Continue to Step 8	Cylinders/piston rings worn	Repair the leak
8	CHECK ON 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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