Engine Runs, But Misses - Lincoln Continental 1964 Shop Manual

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DIAGNOSIS GUIDE (Continued)
ENGINE RUNS, BUT
MISSES
PART 8-1-GENERAL ENGINE SERVICE
8-3
Determine if the miss is steady or
erratic and at what speed the miss
occurs by operating the engine at
various speeds under load.
MISSES STEADILY AT
ALL SPEEDS
Isolate the miss by operating the
engine with one cylinder not firing.
This is done by operating the engine
with the ignition wire removed from
one spark plug at a time, until all cyl-
inders have been checked. Ground
the spark plug wire removed.
If the engine speed changes when
a particular cylinder is shorted out,
that cylinder was delivering power
before being shorted out. If no
change in the engine operation is
evide:nt, the miss was caused by that
cylinder not delivering power before
being shorted out. In this case, check
the:
IGNITION SYSTEM
If the miss is isolated in a par-
ticular cylinder, perform a spark test
on the ignition lead of that cylinder.
If a good spark does not occur,
the trouble is in the secondary cir-
cuit of the system. Check the spark
plug wire and the distributor cap.
If a good spark occurs, check the
spark plug. If the spark plug is not
at fault, a mechanical component
of the engine is probably at fault.
ENGINE
Perform a manifold vacuum test
or a compression test to determine
which mechanical component of the
engine is at fault.
MISSES ERRATICALLY
AT ALL SPEEDS
EXHAUST SYSTEM
Exhaust system restricted.
IGNITION SYSTEM
Breaker points not properly ad-
justed.
Defective breaker points, con-
denser, secondary wiring, coil, or
spark plugs.
High tension leakage across the
coil, rotor, or distributor cap.
FUEL SYSTEM
Float setting incorrect.
Fuel inlet system not operating
propt:rly.
Dirt or water in the fuel lines or
carburetor.
Restricted fuel filter.
COOLING SYSTEM
Check the cooling system for in-
ternal leakage and/ or for a condi-
tion that prevents the engine from
reaching normal operating tempera-
ture.
ENGINE
Perform a manifold vacuum test or
a compression test to determine
which mechanical component of the
engine is at fault.
MISSES AT IDLE ONLY
FUEL SYSTEM
Idle fuel mixture needles not prop-
erly adjusted.
IGNITION SYSTEM
Defective coil, condenser, breaker
points, rotor, ignition, wiring or
spark plugs.
Excessive play in the distributor
shaft.
Worn distributor cam.
ENGINE
Perform a manifold vacuum test or
a compression test to petermine
which mechanical component of the
engine is at fault.
MISSES AT HIGH SPEED ONLY
FUEL SYSTEM
Low or erratic fuel pump pressure.
Fuel inlet system not operating
properly.
Restricted fuel filter.
High-speed system restricted, clog-
ged, or damaged.
Positive crankcase ventilation sys-
tem restricted or valve not operating
properly.
Metering rod piston stuck in down
position.
COOLING SYSTEM
Engine overheating.
ENGINE
Perform a manifold vacuum test
or a compression test to determine
which mechanical component of the
engine is at fault.
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