Fiat 1996 Brava Service Manual page 293

Engine Bravo-Brava @» i
6v
Fuel system 98 range
10.
P4A42JJ01
Table summarizing pollutant emission tolerance values
Upstream of the catalyzer
Downstream of the catalyzer
CO (%)
0 , 4 - 1
< 0,35
HC (p.p.m.)
^ 500
< 90
C02 (%)
> 12
^ 13
Checking concentration of CO and HC at the exhaust
The exhaust concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) is measured by
inserting a suitably calibrated tester sensor at least 30 cm into the end of the exhaust pipe.
1. Check that the idle CO and HC concentrations correspond to the recommended figures (see table).
2. If the HC value is outside of 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.
CHECKING ENGINE IDLE SPEED
If the engine idle speed does not correspond with the one recommended, as the system is the self-ad­
justing type no adjustments can be carried out. It is therefore necessary to check that the accelerator
linkage is correctly adjusted and the cause of the problem should be sought by carrying out a complete
fault diagnosis using the diagnostic equipment.
IGNITION ADVANCE CHECK
The diagnostic equipment must be used to check the ignition advance angles at the different speed.
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