Fiat 1998 Marea Weekend, Service Manual

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Marea- Marea Weekend
9
20v
99 range
Engine
Fuel system
10.
Checking exhaust concentration of CO and HC
The exhaust concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) is meaured by in-
serting a suitably calibrated CO tester probe at leat 30 cm into the end of the exhaust pipe as illustrated in
the diagram.
If the shape of the end section of the exhaust pipe does not allow the sensor to be fully inserted, a special
extension pipe which ensure the seal in the join area must be added.
1. Check that the idle CO and HC concentration figures correspond to those in the table.
2. If the HC value is different from the recommended limit, whilst that measured previously upstream of
the catalyzer was correct, the engine parameters are correct and therefore the cause of the problem
should be sought in the decreased efficiency of the catalyzer.
Table summarizing pollutant emission tolerance values
CO (%)
HC (p.p.m.)
C 0
2
(%)
Upstream of the catalyzer 0.4 - 1
600 12
Downstream of the catalyzer
«S
0,35
> 90 > 13
P 4 F 3 9 Q J 0 I
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