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Panoz Esperante GTS
Panoz Esperante GTS
Panoz Esperante GTS
RVP – Reliability / Value / Performance
Spark Plug Analysis
(Reference plug image chart on page 29)
1-2: Normal
This is a normal looking spark plug. The insulator tip is
greyish white, but could also be greyish yellow to brown.
This indicates that the engine is in good operating condi-
tion and that the heat range of the plug is correct.
3-4: Carbon Deposit
The velvet-like, dull black carbon deposits on the insulator,
electrodes and shell can be caused by any of the following:
incorrect mixture, dirty air filter, faulty automatic choke,
too cold of a spark plug or extreme stop-and-go driving
conditions. To remedy this situation, make appropriate
mixture adjustments, replace the air filter or use a hotter
spark plug in the case of extreme stop-and-go driving
conditions.
5-6: Oil Fouled
The wet, shiny deposits are oil. This excessive quantity
of oil can result from worn cylinders, piston rings or
valves. In a two-stroke engine, it indicates an oil mixture
that is too rich. To correct this problem, repair and/or
replace the worn parts. In either case, new spark plugs
should be installed.
7-8: Lead Deposit
The yellow insulator deposits are from fuel additives con-
taining lead. With higher loads the deposit will become
conductive and can cause misfiring. New plugs should
be installed, because cleaning is ineffective.
9-10: Severe Lead Deposit
The brownish tint in the yellow glazed deposit is a combi-
nation of carbon and lead from fuel and oil additives. They
accumulate on the insulator nose during slow driving
conditions and then melt when the vehicle begins hard
acceleration. As the plug cools, the deposits solidify.
Once again, cleaning and sandblasting are useless;
install new plugs.
11-12: Ash Deposits
The brownish, cinder-like deposits on the electrodes and
insulator are ash residues from oil and gas additives.
The alloying additives leave an unburnable ash in the
combustion chamber and on the spark plug. In serious
cases, it may be necessary to decarbonize the combustion
chamber before installing new spark plugs.
13: Partially Melted Center Electrode
A melted electrode, with a white and/or blistered insu-
lator tip indicates incorrect heat range or insufficient
installation torque. Note: If the insulator has separated
from the shell and the shell is discolored, insufficient
installation torque is the cause. If the shell is not dis-
colored over torquing is the cause. Spark plug misfir-
ing will occur and engine damage can result. A thor-
ough tune-up should be performed, and the appropri-
ate plug application heat range should be verified
before installing any new spark plugs.
14: Melted Center Electrodes
The melting of the center electrode is the result of
abnormal combustion; for example, knocking or over-
advance ignition timing. Misfiring will occur. Power loss
and possibile engine damage can result. A thorough
tune-up with new plugs is necessary.
15: Partially Melted Electrodes
A melted ground electrode can be caused by pre-ignition
Pre-ignition can result from hot spots in the combustion
chamber, over-advanced ignition timing, lean air/fuel
mixtures, defective distributor advance mechanisms,
deposits in the combustion chamber, defective cylinder
head or manifold gaskets. To avoid pre-ignition, a
thorough tune-up is required before installing new
spark plugs.
16: Center Electrode Erosion
This erosion is caused by not observing replacement
intervals. Misfiring and poor starting behavior will result.
Install new spark plugs.
17: Ground Electrode Erosion
This electrode erosion was the result of aggressive
fuel and oil additives. It was further aggravated by
unfavorable gas turbulence in the combustion chamber
caused by heavy deposits. This is not a heat range
problem. Effects include hard starting and hesitation
on acceleration. Install new spark plugs.
18: Insulator Nose Breakage
This damage is from impact, drop or pressure on the
center electrode. If the plug has been used for too
long, the insulator nose can be cracked by deposits
between the center electrode and the insulator and
from corrosion of the center electrode. New spark
plugs should be installed.
