ENGINE MANAGEMENT SYSTEM
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DO: Spark plug wires(secondary leads) & primary
wiring:
- must not contact sharp surface
- must not be under tension between fixed points
- must be clear of moving parts (belts, fan, etc…)
- must be protected from or kept at least 125 mm
away from radiant heat source exceeding 400 F.
- must be protected from environmental damage
(dirt, splash, oils, fluids, etc….)
- must be retained, secured or insulated to
prevent pinching, mis-routing, rattles, and
squeaks
- Spark plug wires carry very high voltage
(30,000 volt). If the secondary lead loses its
dielectric characteristics thru being nicked, cut ,
chaffed, then an arc thru to a near by ground
could take place. This kind of condition could
lead to misfire, no start, or premature failure of
ignition system.
DO: Not all fasteners are designed for repeat use.
Beware of fastener specifications. All harnesses
should be supported within 6" of a mating
connection.
Adequate retention force might not be achieved
if the fastener is not designed to be reused.
Mating connections are not designed to support
the weight of the harness assembly.
DO: For removing spark plugs follow the following
steps:
1- Grasp the spark plug boot and gently
2- rotate 90°; and then pull the spark plug boot
and cable away from the spark plug
3- Before removing spark plug, brush or air blast
dirt away from the well areas
4- Use correct size deep socket wrench to
loosen each spark plug one or two turns
To remove spark plugs from Aluminum heads,
allow the engine to cool. The heat of the engine,
in combination with a spark plug that is still hot,
may cause the spark plug threads to strip the
cylinder head upon removal
Use goggles to protect eyes from dirt when
applying compressed air to spark plug wells
DO: Cleaning a spark plug could be done as
follow:
1- wipe all spark plug surfaces clean….remove
oil, water, dirt and moist residues.
2- If the firing end of spark plug has oily or wet
deposit, brush the spark plug in an approved,
non-flammable and non-toxic solvent. Then
dry the spark plug thoroughly with
compressed air
3- Use a propane torch to dry wet-fuel fouled
plugs. Allow the torch flame to enter up the
center electrode insulator. Allow plug to cool
down
4- If the spark plug threads have carbon & scale
deposits, clean with wire brush, taking care
not to injure the electrode or the
insulator tip
-Cleaning a spark plug will reduce the voltage
required for an electrical arc(spark) across the
electrodes
-Cleaning & re-gapping will not restore a used
spark plug to a new condition. It may be more
economical and efficient to replace used spark
plugs with new plugs instead of cleaning.
-Sooted plugs should be replaced
-Do not cool by using water or any liquid
-Clean threads permit easier installation and
proper seating which will maximize transfer heat
away from the plug
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