2427479 - D10 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).
Results of the tests
0PRELIMINARY CHECKSAll OKProblems metOperation

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 1Spark plugs dirty or defectiveReplace the spark plugs Op.   5510D10 
Leads defectiveReplace the spark plug leads Op. 5510D14
Air filter blockedReplace the filter element
Fault in air intake circuitRestore the correct operation of the intake circuit
1CHECKING WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
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 detectedSee table   Z50 
Another error dectected in the control unitContinue following the instructions for the diagnostic equipment
Inconsistent parameterContinue following the instructions for the diagnostic equipment
2IDLE ACTUATOR CHECKAll OKProblems metOperation
Check that the system carries out the correct idle learning procedureContinue to Step 3Irregular idlingCarry out the idle learning procedure correctly
3PETROL VAPOUR RECOVERY SYSTEM CHECKAll OKProblems metOperation
Check the condition and seal of the petrol vapour recovery pipesContinue to Step 4Air seepageRestore the correct seal
Pipe from canister to solenoid brokenReplace the pipe
4PETROL VAPOUR RECOVERY SOLENOID VALVE CHECKAll OKProblems metOperation
Carry out active diagnosis of solenoid valve.Continue to Step 6Solenoid not workingContinue to Step 5
5SOLENOID VALVE ELECTRICAL CIRCUIT CHECKAll OKProblems metOperation
Check supply and earth of petrol vapour recovery solenoid See   E5030  PETROL ENGINE ELECTRONIC MANAGEMENT Continue to Step 6Solenoid valve faultyReplace the solenoid valve Op.   1080E28 
Connections not correctRestore the connections See   E5030  PETROL ENGINE ELECTRONIC MANAGEMENT
6BRAKE SERVO AND PIPE CHECKAll OKProblems metOperation

Check condition of:

  • brake servo vacuum pipes;
  • brake servo.
Continue to Step 7Brake servo pipe defectiveReplace the pipe
Brake servo defectiveReplace the brake servo/pump assembly
7CHECK ON FUEL PRESSUREAll OKProblems metOperation
Check the fuel supply pressure Op.   0510C10  Continue to Step 8Insufficient fuel pressure: pipe obstructedEliminate the blockage; if necessary replace the pipe
Low fuel pressure: clogged filterReplace the pump assembly
Insufficient fuel pressure: regulator out of calibrationReplace the pump assembly
Low fuel pressure: defective pumpReplace the pump assembly
8CHECK ON TIMINGAll OKProblems metOperation
Check that the timing is correctContinue to Step 9Timing not correctRestore the correct timing
9CHECK ON CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosisFault persists: control unit faultyReplace control unit ( Op.   1056B82