Engine does not produce best performance

Make: Fiat
Model: Stilo Factory Service Manual
Year: 2001–2007
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

1.2 16v, 1.6 16v, 1.8 16v, 2.4 20v

There are decreases in performance during acceleration

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 no obstructions in the exhaust pipe	Continue to Step 1	Air intake circuit check	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. 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
			Another error dectected in the control unit	Continue following the instructions for the diagnostic equipment
			Another error dectected in the control unit	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 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
			Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
			Sudden occurrence of another error detected	Continue following the instructions for the diagnostic equipment
3	FUEL PRESSURE ROAD TEST	All OK	Problems met	Operation
1.8 16v 2.4 20v	Road test the vehicle and check the fuel supply pressure in the conditions that lead to the anomalyOp. 0510C10	Continue to Step 4	Insufficient fuel presure: pipes obstructed	Eliminate the obstructions
1.8 16v 2.4 20v		Continue to Step 4	Insufficient fuel pump: pump faulty	Replace pump assembly Op. 1040A70
1.2 16v 1.6 16v	Road test the vehicle and check the fuel supply pressure in the conditions that lead to the anomalyOp. 0510C10	Continue to Step 10	Insufficient fuel presure: pipes obstructed	Eliminate the obstructions
1.2 16v 1.6 16v		Continue to Step 10	Insufficient fuel pump: pump faulty	Replace pump assembly Op. 1040A70
4	MODULAR MANIFOLD SOLENOID CHECK	All OK	Problems met	Operation
1.8 16v 2.4 20v	Carry out active diagnosis of modular manifold solenoid	Continue to Step 6	Faulty solenoid	Continue to Step 5
5	MODULAR MANIFOLD SOLENOID CIRCUIT CHECK	All OK	Problems met	Operation
1.8 16v 2.4 20v	Check the supply and earth of the modular manifold solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 6	Solenoid valve faulty	Replace the solenoid valve
1.8 16v 2.4 20v		Continue to Step 6	Connections not correct	Restore connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
6	CHECK MODULAR MANIFOLD	All OK	Problems met	Operation
1.8 16v 2.4 20v	Check the modular manifold is working properly.	Continue to Step 7	Pneumatic actuator not working.	Restore the correct connection See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT If necessary, replace the actuator
1.8 16v 2.4 20v	Check the modular manifold is working properly.	Continue to Step 7	Faulty manifold	Replace the manifold
7	Check variable valve timing system manifold	All OK	Problems met	Operation
1.8 16v 2.4 20v	Carry out active diagnosis of variable valve timing	Continue to Step 9	Faulty solenoid	Continue to Step 8
8	CHECK ON TIMING VARIATOR ELECTRICAL CIRCUIT	All OK	Problems met	Operation
1.8 16v 2.4 20v	Check power and earth of variable valve timing system solenoid See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT	Continue to Step 9	Variable valve timing system faulty	Replace the phase transformer
1.8 16v 2.4 20v		Continue to Step 9	Connections not correct	Restore connections See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
9	CHECKING VARIABLE VALVE TIMING SYSTEM	All OK	Problems met	Operation
1.8 16v 2.4 20v	Check the operation of the variable valve timing system by powering the solenoid of the variator directly during idling. There must be a significant change in engine speed (surging or very irregular idle)	Continue to Step 10	There are no changes in engine speed: timing variator stuck	Replace the phase transformer
10	CHECKING TIMING	All OK	Problems met	Operation
	Check that the timing is correct	Continue to Step 11	Timing incorrect	Restore the correct timing
11	CHECKING CYLINDER COMPRESSION	All OK	Problems met	Operation
	Carry out the cylinder compression test Op. 0510A10	Continue to Step 13	Insufficient cylinder compression	Continue to Step 12
12	CHECKING 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 13	Insufficient valve seal	Overhaul the cylinder head
		Continue to Step 13	Cylinders/piston rings worn	Repair the leak
13	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists: control unit defective	Replace control unit Op. 1056B82 Search for the fault starting from another symptom'

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Parts & tools for this job For 2001 Fiat Stilo

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