Fiat Bravo Service Manual page 270

Engine Bravo-Brava © i ^
Fuel system
10.
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
CO2 (%)
> 12
> 13
Checking exhaust concentration of CO and HC
The concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) at the exhaust is mea­
sured by inserting a suitably calibrated sensor probe at least 30 cm into the end section of the exhaust
pipe.
1. Check that the idle CO and HC concentration values are as recommended (see table).
2. If the HC value is outside of the recommended limits, whilst that previously measured upstream of the
catalyzer was okay, then the engine parameters are taken to be correct and the cause of the problem
should be sought in the decreased efficiency of the catalyzer.
CHECKING ENGINE IDLE SPEED
If the engine idle speed is not correct as the system is the self-adjusting type it is not possible to carry out
any adjustment: therefore it is necessary to check that the accelerator linkage is correctly adjusted and
therefore the problem should be sought by means of a complete fault diagnosis using the F/L Tester.
CHECKING IGNITION ADVANCE
In order to check the ignition advance values at different speeds it is necessary to use the F/L Tester di­
agnostic equipment.
58 Print no. 506.670