22 · Diagnostics

Engine idle irregular

Make: Fiat
Model: Doblò Factory Service Manual
Year: 2000–2010
Section: Engine › Engine idle irregular

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Fault diagnosisEngine idle irregular

ENGINE IDLE IRREGULAR

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.).

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the state of the spark plugs and leads; the condition of the air filter the condition of the air intake circuit	Continue to Step 1	Spark plugs dirty or defective	Replace the spark plugs Op. 5510D10
			Leads defective	Replace the spark plug leads Op. 5510D14
			Air filter blocked	Replace the filter element Op. 1048A14
			Fault in air intake circuit	Restore the correct operation of the intake circuit
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	IDLE ACTUATOR CHECK	All OK	Problems met	Operation
	Carry out active diagnosis of idle actuator	Continue to Step 4	Actuator not working	Continue to Step 3
3	IDLE ACTUATOR ELECTRICAL CIRCUIT CHECK	All OK	Problems met	Operation
	Check the supply and earth of the idle actuator See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 4	Actuator faulty	Replace the idle actuator
		Continue to Step 4	Connections not correct	Restore the connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
4	PETROL VAPOUR RECOVERY SYSTEM CHECK	All OK	Problems met	Operation
	Check the condition and seal of the petrol vapour recovery pipes	Continue to Step 5	Air seepage	Restore the correct seal
		Continue to Step 5	Pipe from canister to solenoid broken	Replace the pipe Op. 1080A62
5	PETROL VAPOUR RECOVERY SOLENOID VALVE CHECK	All OK	Problems met	Operation
	Carry out active diagnosis of solenoid	Continue to Step 7	Solenoid not working	Continue to Step 6
6	SOLENOID VALVE ELECTRICAL CIRCUIT CHECK	All OK	Problems met	Operation
	Check supply and earth of petrol vapour recovery solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 7	Solenoid valve faulty	Replace the solenoid valve Op. 1080E28
		Continue to Step 7	Connections not correct	Restore the connections See E3040 CENTRAL LOCKING
7	BRAKE SERVO AND PIPE CHECK	All OK	Problems met	Operation
	Check condition of: brake servo vacuum pipes; brake servo (see Test 3330DA)	Continue to Step 8	Brake servo pipe defective	Replace the pipe Op. 3330D24
		Continue to Step 8	Brake servo defective	Replace the brake servo/pump assembly Op. 3330D24
8	CHECK ON FUEL PRESSURE	All OK	Problems met	Operation
	Check the fuel supply pressure Op. 0510C10	Continue to Step 9	Insufficient fuel pressure: pipe obstructed	Eliminate the blockage; if necessary replace the pipe Op. 1040B34
			Low fuel pressure: clogged filter	Replace the pump assembly Op. 1040A70
			Insufficient fuel pressure: regulator out of calibration	Replace the pump assembly Op. 1040A70
			Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
9	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct Op. 0510C10	Continue to Step 10	Timing not correct	Restore the correct timing Op. 1032B10
1.2 8v Climatizzatore	Check that the timing is correct Op. 0510A20	Continue to Step 10	Timing not correct	Restore the correct timing Op. 1032B14
10	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 is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.).

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the condition of the air filter the condition of the air intake circuit	Continue to Step 1	Air filter blocked	Replace the filter element Op. 1048A14
		Continue to Step 1	Fault in air intake circuit	Restore the correct operation of the intake circuit
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	Continue according to the instructions for the 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	PETROL VAPOUR RECOVERY SYSTEM CHECK	All OK	Problems met	Operation
	Check the condition and the seal of the pipe between the canister solenoid valve and the intake manifold	Continue to Step 3	Air seepage	Restore the correct seal
		Continue to Step 3	Pipe between solenoid valve and manifold damaged	Replace the pipe
3	PETROL VAPOUR RECOVERY SOLENOID VALVE CHECK	All OK	Problems met	Operation
	Carry out active diagnosis of solenoid	Continue to Step 5	Solenoid not working	Continue to Step 4
4	SOLENOID VALVE ELECTRICAL CIRCUIT CHECK	All OK	Problems met	Operation
	Check supply and earth of petrol vapour recovery solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 5	Solenoid valve faulty	Replace the solenoid valve Op. 1080E28
		Continue to Step 5	Connections not correct	Restore the connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
5	BRAKE SERVO AND PIPE CHECK	All OK	Problems met	Operation
	Check the condition of the brake servo vacuum pipes; Check the operation of the single-active valve and the brake servo	Continue to Step 6	Brake servo pipe defective	Replace the pipe
		Continue to Step 6	Brake servo defective	Replace the brake servo/pump assembly
6	CHECK ON FUEL PRESSURE	All OK	Problems met	Operation
	Check the fuel supply pressure Op. 0510C10	Continue to Step 10	Insufficient fuel pressure: pipe obstructed	Eliminate the blockage; if necessary replace the pipe
	Check the fuel supply pressure Op. 0510C10	Continue to Step 10	Low fuel pressure: defective pump	Replace the pump assembly Op. 1040A70
7	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 11	Timing not correct	Restore the correct timing
8	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 is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.).

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check the condition of the air intake circuit Check the condition of the air cleaner and make sure it is working properly Check that there is diesel in the tank and its quality is good	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
			Filter blocked	Replace the filter element Op. 1048A14
			Diesel of poor quality	Clean the tank Op. 1040A10and put diesel in it
1	CHECKING WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket check for errors in the control unit plausibility of all the parameters	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	unreliable parameters	Continue following the instructions for the diagnostic equipment
2	CHECK ON FUEL INJECTION PUMP TIMING	All OK	Problems met	Operation
	Check the timing of the fuel injection pump Op. 1060A20	Continue to Step 3	Fuel injection pump timing set incorrectly	Restore the correct timing Op. 1060A20
3	CHECK ON INJECTORS	All OK	Problems met	Operation
	Check the injectors for leaks and that they are correctly calibrated Op. 1060A20	Continue to Step 4	Incorrect injector calibration	Restore the correct calibration Op. 1060B10
		Continue to Step 4	Faulty injectors	Replace the injectors Op. 1060B10
4	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 5	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 obstructions; if necessary replace the pipes
5	CHECK 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 stuck in open position	Replace the EGR valve Op. 1080C10
6	CHECK AIR CONDITIONING SYSTEM	All OK	Problems met	Operation
1.9 DIESEL Climatizzatore	Road test the vehicle and check whether the fault is affected by whether or not the air conditioner is switched on	Continue to Step 7	Fault present only with the air conditioner on	See table L10 CLIMATE CONTROL NOT COOLING
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	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. 1060D80

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.).

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	check the condition of the air intake circuit condition and correct operation of the air filter	Continue to Step 1	Fault in air intake circuit	Repair the air intake circuit
		Continue to Step 1	Air filter blocked	Replace the filter element Op. 1048A14
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 errors in the control unit plausibility of all the parameters carry out active diagnosis of E.G.R. solenoid	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
			unreliable parameters	Continue following the instructions for the diagnostic equipment
			Lack of dialogue with the control unit	Restore the connection between engine management control unit and diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
			Solenoid not working	Check the continuity of the wiring See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT, if necessary, replae the solenoid valve
2	CHECK ON FUEL FILTER	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 the tank and pipes and replace the diesel filter cartridge Op. 1044B20
3	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct.	Continue to Step 4	Valve clearance not correct	Adjust the tappets Op. 1036H10
4	CHECK ON CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test	Continue to Step 6	Cylinder compression insufficient	Continue to Step 5
5	CHECKING CAUSE OF INSUFFICIENT COMPRESSION	All OK	Problems met	Operation
	Carry out R.R. on head to check the valve seal and check the condition of the cylinders/piston rings	Continue to Step 6	Insufficient valve seal	Overhaul the cylinder head Op. 1016E10
6	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 engine management control unit Op. 1060G80

BIPOWER

The engine is not running smoothly when idling; in particular, it does not maintain a constant, regular value as the load varies (e.g. when electrical devices are switched on, etc.).

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Preliminarily check: the condition of the air intake circuit condition of air filter the condition of the methane filter the state of the spark plugs and leads that the valve tappet clearance is correct	Continue to Step 1	Air intake circuit component damaged	Replace damaged component
			Filter element dirty or damaged	Replace the filter element
			Methane filter dirty or damaged	Replace the methane filter
			Spark plugs dirty or damaged	Clean or replace the spark plugs
			Spark plug leads damaged	Replace the spark plug leads
			Valve clearance not correct	Restore the correct valve clearance
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 engine management control units: in errors ambient: that there are no faults in the petrol engine management control unit that there are no faults in the mehtnane engine management control unit; in parameters ambient: the plausibility of all the parameters. methane injectors fault diagnosis after carrying out a servicing operation, check that the self-adjustment parameters are zeroed	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
			unreliable parameters	Continue following the instructions for the diagnostic equipment
			Injector defective	Replace the injector
			The self-adjustment parameters have not been reset	Use the Examiner to reset the self-adjustment parameters
2	METHANE PRESSURE CIRCUIT LEAKAGE TEST	All OK	Problems met	Operation
	Check the seal of the high and low pressure system by carrying out the test See Test 1058C Methane high pressure circuit leakage test	Continue to Step 3	System not sealed	Renew the seal
3	IDLE ACTUATOR CHECK USING DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Using the Examiner diagnostic equipment connected to the diagnostic connector, check the following at the petrol engine management control unit: In active diagnosis mode: that the idle actuator is working properly	Continue to Step 4	Idle actuator defective	Replace the idle actuator
			Idle actuator push rod seat dirty	Clean the idle actuator push rod seat
			Actuator connection not correct	Restore the correct connection between the idle actuator and the engine management control unit
4	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: that the pressure in the methane circuit is correct by carrying out the test See Test 1058A Check on methane pressure in high pressure circuit and Test See Test 1044EB Check on methane low pressure circuit	Continue to Step 5	Pressure not correct: methane pressure reduction unit defective	Replace the methane pressure reduction unit Op. 1044E10
			Pressure not correct: Methane pressure sensor stuck	Replace the methane pressure sensor Op. 1044E16
			Pressure not correct: Methane leaks from the system	Eliminate the leaks from the methane system
5	METHANE INJECTORS 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 active diagnosis mode: that the methane injectors are working properly Check that the injectors are not leaking by carrying out the test See Test 1058B Methane injector leakage test	Continue to Step 6	Methane injector defective	Replace the injector Op. 1058A70
		Continue to Step 6	Methane injectors always open	Replace the injectors
6	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 7	Timing not correct	Restore the correct timing
7	CHECK ON TIMING	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

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