Fiat 1998 Marea Weekend, Service Manual

Page: 316 / 846

Engine
Fuel system
Marea- Marea Weekend 9
99 update
10.
Table summarizing pollutant emission tolerance figures
CO (%) HC (p.p.m.)
C 0
2
(%)
Upstream of the catalyzer 04 - 1 < 500 > 12
Downstream of the catalyzer
<0.35 < 9 0 ' > 13
Checking exhaust concentration of CO and HC
The concentration of carbon monoxide (CO) and unburnt hydrocarbons (HC) at the exhaust 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, then the engine parameters are correct the cause of the problem should be sought
in the decreased efficiency of the catalyzer.
CHECKING ENGINE IDLE SPEED
If the engine idle speed does not correspond to the recommended figure and the system is the self-
regulating type, then no adjustment can be carried out: it is therefore necessary to check that the accel-
e r a t o r
linkage is correctly adjusted and the cause of the problem should be sought by carrying out a com-
p l e t e
fault diagnosis using the diagnostic equipment.
CHECKING IGNITION ADVANCE
The diagnostic equipment must be used to check the ignition advance angles at the different speeds.
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Print n° 506.763/15