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1.2L REVOTRON ENGINE
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Inspection :
The condition of the spark plug provides a
good indication of the engine running
condition. Knowing what to look for can
provide insight to operating conditions and
help to pinpoint problems with operation.
"Read" the spark plug to determine engine
operating condition.
1. Normal -
The spark plug core will be
lightly coated with grey or brown deposits.
Heavy deposits indicate the use of fuel or oil
additives. The electrode will not be worn
excessively or nicked. The gap will only
increase 0.01 mm for every 2000 km of use
with the correct fuel. Clean and reuse if
replacement is not required.
2. Carbon Fouling -
Dark sooty deposits will
be present on the entire spark plug. This
may cause the electrode to short-circuit,
weakening or eliminating spark. Typically
caused by excess fuel from a leaking fuel
injector, sticking idle speed control valve, or a
clogged air filter. Replace the spark plugs if
carbon fouled.
3. Oil Fouling-
Heavy wet deposits indicate the
spark plug is oil fouled. Oil fouling occurs when
engine oil is entering the combustion chamber
from defective piston rings, valve guides or
seals, or a blown head gasket. May also occur
during run-in/break In on new or
overhauled engines. Replace the spark plugs
if oil fouled.
4. Overheating-
Overheating is typically
caused by the over-advancement of
ignition timing, a lean fuel mixture, incorrect
spark plug heat range, or incorrect fuel
octane rating. Electrodes and insulator will be
white and may show signs of wear. Replace
overheated spark plugs.
5. Detonation
- A detonation or pre-ignition
condition will look the similar to an
overheating condition, but wear and damage
will be much worse such as insulator
cracking or breaking. Typically caused by
the wrong grade of fuel, incorrect spark plug
heat range, or an extremely lean condition.
The problem must be identified and repaired
immediately otherwise severe engine
damage will occur. Do not reuse broken or
cracked spark plugs.