Removing-refitting engine control unit

Removing-refitting engine control unit

The control unit is located under the glove compartment.

Proceed with removing the control unit by carrying out the following operations:

• remove the glove compartment;
• undo the bolt fixing the mounting bracket and rest the control unit on the floor of the vehicle;
• undo the bolt fixing the earth cable to the bodyshell;
• disconnect the electrical connectors, one by one;
• remove the bracket from the control unit.

CHECKING EMISSION CONCENTRATION

This system manages the content of carbon monoxide (CO) and the idle air flow rate which cannot, however, be manually adjusted.

However, checking the content of the exhaust gases upstream and downstream of the catalyzer can provide a useful indication of the injection/ignition system operating conditions, the engine parameters and the catalyzer.

Checking idle concentration of CO and HC upstream of the catalytic silencer

In order to check the concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) upstream of the catalyzer, proceed as follows:

1. Undo the cap located in the exhaust pipe, upstream of the catalyzer, and tighten the tool in its place.
2. Connect a suitably calibrated CO-tester sensor to the tool.
3. Start up the engine and let it reach operating temperature.
4. Check that the speed is correct.
5. Check that the idle concentration of CO is within the recommended limits (see table); if this is not the case, it is necessary to check:
   • that the Lambda sensor is working properly, using the F/L Tester;
   • for the presence of air penetration in the area surrounding the Lambda sensor housing;
   • the injection and ignition systme (in particular the state of wear of the spark plugs).
6. In the same conditions, check that the concentration of HC is less than 500 p.p.m.
7. If these values are not found, proceed with checking the engine, paying particular attention to:
   • the timing;
   • the engine compression.

NOTE The engine is fitted with hydraulic tappets for the automatic recovery of the clearances.