2239 - 2003 Website Pages - Autolite

1 May 2003 Autolite Autolite Technical InformationTechnical Information1. NORMAL3. FUEL FOULED5. WORN OUT6. GLAZING2. NORMAL WITH RED COATING7. CARBON FOULED4. DETONATION8. SUSTAINED PREIGNITION9. ASH DEPOSITS10. OIL FOULED11. MECHANICAL DAMAGE12. LEAD FOULEDPLUG TIPS TELL THE at spark plug firing tips can tell you if yourengine has a problem that needs correcting. Theyreflect the performance of a well-tuned engine or apoorly maintained though spark plugs are easily replaced, inexpen-sive and immediately improve engine performance,they are often ignored until they cause serious per-formance problems. Bad plugs can cause overheating,rough running, power loss and even engine your spark plugs regularly, and use this chart asa guide to spot performance NORMALR ecommendation: Correct heat range of spark plug is beingused. Replace with the equivalent Autolite spark plug at theproper NORMAL WITH RED COATINGR ecommendation: Normal - coloration is from the use of addi-tives in unleaded FUEL FOULEDR ecommendation: Indicates the cylinder from which the sparkplug came is not using all the fuel supplied to it.

2 Check forfaulty or sticking choke, overly rich fuel mixture, ignition prob-lems, leaking fuel injectors, or spark plug heat range is DETONATIONR ecommendation: Caused by low octane fuel or over advancedtiming. Can be noticed as engine knock. Check for faulty EGRsystem, detonation sensor, and correct spark plug heat WORN OUTR ecommendation: Spark plug used beyond its intended with a new set of Autolite spark GLAZINGR ecommendation: Spark plug is operating too hot at highspeeds. Replace with a colder heat range of Autolite CARBON FOULEDR ecommendation: Spark plug heat range is too cold and/orcaused by extensive low-speed, short distance with the correct heat range of Autolite spark caused by weak ignition system and/or rich fuel injection engines would produce carbon fouling from clogged fuel injectors, vacuum leaks, and/or problem with carbon canister/purge valve operation. Carburetor equippedengines cause carbon fouling from improperly adjusted or malfunctioning SUSTAINED PREIGNITIONR ecommendation: Check for correct application of spark plug(heat range too hot, wrong spark plug for engine), cross firingof ignition cables, over advanced timing, lean fuel mixture,defective EGR valve, accumulation of combustion chamberdeposits, hot spots in the combustion chamber due to poorheat dissipation, improper installation torque applied to sparkplug, and/or head gasket protrusion into the combustion ASH DEPOSITSR ecommendation: Caused by the use of leaded fuel, fuel additives, and/or oil additives.

3 Check for worn piston ringsand/or valve guides. Misfiring may occur due to the depositson the OIL FOULEDR ecommendation: Caused by presence of oil in the combus-tion chamber. Check for worn rings, worn valve guides, and/orworn valve MECHANICAL DAMAGE (New Catalog Addition)Recommendation: Locate and remove foreign object frominside of catalog for proper spark plug application. Improper spark plug thread reach can protrudeinto cylinder and sustain LEAD FOULEDR ecommendation: Occurrence is from use of leaded fuel orfuel additives containing lead which become conductive overthe firing tip. Install new spark : Grayish-tan to white : Pinkish-red color on the ceramic insulator tip,the center electrode, and the ground : Firing tip is damp with gasoline, usually theodor of fuel is present on the spark plug. The insulator is oftentinted the color of : Insulator is usually cracked, chipped, or bro-ken. Ground electrode can also exhibit : Center and ground electrodes are eroded, haverounded edges, and are excessively worn away.

4 Difficultystarting engine and misfiring during acceleration may :Ceramic insulator tip appears to have a melted, glazed : Black, sooty coating on firing : Melted center and ground electrodes and dam-aged ceramic insulator tip. Initial and sustained preignition aretwo extremes of the same engine : Center electrode, ground electrode, and/orceramic insulator tip are coated with tan colored : Center electrode, ground electrode, and/orceramic insulator tip are coated with a black, oily : Center electrode and ground electrode arebent out of position, down or to one side of the spark tip is broken and missing from the firing :Ceramic insulator tip is coated with a brownish-yellow glazed coating.