Fiat 1996 Brava Service Manual page 345

Bravo ft 20v
98 range
Engine
Fuel system
10.
Checking exhaust concentration of CO and HC
The exhaust concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) is measured by
inserting a suitably calibrated CO tester probe at least 30 cm into the end of the exhaust pipe as shown in \
the diagram.
If the shape of the end of the exhaust pipe is such that the sensor cannot be fully introduced, a special ex­
tension pipe which guarantees the seal in the join area must be added.
1. Check that the idle CO and HC concentrations are the same as those in the table.
2. If the HC value differes from the recommended limit, whilst that measured previously upstream of the
catalyzer was correct, the engine parameters are correct and the cause of the problem should there­
fore be sought in the decreased efficiency of the catalyzer.
Table summarizing pollutant emission tolerance figures
Upstream of the catalyzer
Downstream of the catalyzer
CO (%)
0,4 - 1
^ 0,35
HC (p.p.m.)
600
^ 90
CO2 (%)
> 12
> 13
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