Table of Contents
Advertisement
EMISSION CONTROL & REGULATIONS 6 4
HYDROCARBONS
r
Hydrocarbons are unburnt gasoline vapors and can be measured E n two different ways. The
first
is t o
measure the weight of the pollu tans over
a
specific distance such as grams per mile or grams
per
kilometer.
The second method is t o measure
the
concentration of HC in the exhaust
gas in parts per million
(PPM).
The most common cause of high HC emissions
are ignition system
problems. If the ignition system fails to
r
ignite the fuel mixture properly, then raw gasoline vapors will pass through the engine into the exhaust
system. Listed are the most common ignition problems which occur and which can affect HC emission
output.
FGMlTlON SYSTEM MALFUNCTIONS
1. Spark Plugs
-
Fouled, dirty,
improper type
or improperly gapped.
2.
Ignition Timing
-
Advanced
or
Retarded.
3.
f iming Advance
- Too fast
or
too
slow
an advance
rate.
4, Battery
-
t o w charge or fau tty.
Carburetion can also lead to high HC emissions i f
the
mixture is
either
excessively
rich
or excessively lean.
MIXTURE-RELATED MALFUNCTIONS
1. Air
Cleaner
-
Dirty, over oiled
or
torn.
2. Jets
-
Clogged, restricted or incorrect
sire,
3.
Float
Level
-
Level too
low
(lean) or too
high (rich).
4. Choke -
Leaking choke plunger
or
sticking linkage.
5. Air Leaks
-
Intake manifolds, engine gaskets and other sealing surfaces.
6. Synchronization
-
Unbalanced on multi-cylinder machines.
7.
Exhaust
System
-
Restricted flow or improper exhaust system.
Engine wear or damage can also cause high HC emissions.
I
I
1. Rings
-
Low compression, leakage into crankcase.
2.
Valves
-
Improper
adjustment,
bent stem or burnt.
3.
Gaskets
-
t e a king,
loss
of compression.
4. Crank
Seals
-
Leaking.
5.
Oil Consumption
-
Worn valve guide,
worn rings,
clogged crankcase
breather.
6 . Oil
-
Improper engine oil.
7
Advertisement
Table of Contents
