Fiat Bravo Service Manual page 269

Bravo-Brava ©^v Engine
Fuel system
10.
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.
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 pro­
vide 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) up­
stream 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.
CHECKING EMISSION CONCENTRATION
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