Introduction
The engine control system on the diavel uses a sensor that measures air temperature. This sensor has a resistance of ntc type (negative temperature coefficient), that reduces its own value when the temperature increases. The air temperature sensor allows the engine control unit to modify the fuel-air mixture and ignition advance in relation to the atmospheric air temperature.
Components assembling position
The air temperature sensor is mounted on the right hand air intake (the image also shows the location of the connection).
Wiring diagram
Ccm engine control connection, s air temperature sensor. 1 Green/blue - g/b, 2 black/purple - bk/v.
In the event of fault
In the event of an air temperature sensor fault, the engine control unit implements a recovery value of 25C.
Fault codes generated and possible correlated faults
Fault codes generated by the engine control unit and displayed by the dds (intake air temperature sensor diagnosis):
Note
Check integrity of electric circuit - short-circuit to vdc = with dashboard on, using a voltmeter, a voltage is measured between the wire tested and ground.
Check integrity of electric circuit - short-circuit to ground = with the battery cables disconnected, using an ohmmeter, continuity is detected between the wire tested and ground.
Check integrity of electric circuit - open circuit = with the battery cables disconnected, using an ohmmeter, no continuity is detected between the two ends of the wire tested.
The dashboard service display shows the error "air temperature" and the eobd warning light activates.
Possible correlated faults: inadequate engine power, irregular idle speed (target idle speed is 1350 rpm with engine stabilised at operating temperature), the engine does not start easily. Check: -sensor resistance, which must be approximately 2 kohm at 25 C.
The air temperature value may be checked using the dds. Check that the value given is plausible.
If none of the aforementioned tests identify the problem and the air temperature sensor is in proper working order, replace the engine control unit.
Component replacement methods
No special measures are necessary in order to replace the air temperature sensor.
Removal of the movable tensioner/timing belt
Loosen the nut (8) and remove the washer (7) and the tensioner pulley (9)
from the pin (12) on the cylinder head.
Remove the timing belt (14) from the horizontal cylinder assembly.
Important
If the belts are to be re-used, mark the direction of rotation with an
arrow and also mark the cylin ...
Refitting the external components
Fit the cap (39) on spring (38) until it engages.
Mount ball (40), spring (38) with cap (39), washer (37) and screw (36) on the
chain side half-casing by starting the
screw into hole (f).
Note
The spring (38), with cap (39), must be oriented as shown.
Tighten the screw fully home to a torqu ...
Refitting the timing belts
Rotate the pulleys on the timing belt driveshaft until the timing mark on the
outer roller is aligned with the mark on the
clutch-side crankcase cover.
In this condition, the horizontal cylinder piston will be at top dead centre.
Install in the alternator cover seat the tool code 88713.20 ...