Diagnosis; Possible Causes Of Emissions Test Failures - Suzuki Samurai 1986 Service Manual

5-2. DIAGNOSIS

POSSIBLE CAUSES OF EMISSIONS TEST FAILURES

Excessive Emission
Hydrocarbons (HC)
Carbon monoxide (CO)
Oxides of nitrogen (Nox)
Explanation
Excessive hydrocarbons are
caused by an air/fuel mixture
that is not burning completely.
Excessive carbon monoxide
emissions are due to a mixture
that is rich.
Excessive oxides of nitrogen
are generally due to high tem-
peratures in the combustion
chamber.
Possible Causes
Engine not at normal operating temperature
l
Disconnected, obstructed, leaking, or misrouted
l
vacuum hoses
Vacuum leaks
l
Maladjusted idle mixture
l
Improper adjusted/sticking choke
l
.
Maladjusted initial spark timing
l
Malfunctioning MCV
l
Lead contamination of catalytic converter
l
Malfunctioning feed back system
l
Engine not at normal operating temperature
l
Improperly adjusted/sticking choke
l
Lead contamination of catalytic converter
l
Leaking carburetor fuel passages or gaskets
l
Malfunctioning feed back system
l
Obstructed/Ieaking/misrouted vacuum lines
l
Plugged EGR passages
l
Inoperative BVSV or TWSV
l
Lead contamination of catalytic converter
l
Malfunctioning feed back system
l
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