Spark Plugs

HAVE YOU CHECKED YOURSPARK PLUGS?SPARK PLUGS CANTELL YOU A LOT ABOUTWHAT’S GOING ONINSIDE AN ENGINE. BYANALYZING THECOLOR, GAP ANDDEPOSITS FOUND ONNORMAL WORN OUT INSULATOR GLAZINGSYMPTOMS A grayish tan to white colorindicates the correct heat range spark plugis in use, the fuel and ignition systems arein good shape and overall engine mechanicalcondition is good.RECOMMENDATIONS Replace with spark plugsof the same heat range.SYMPTOMS Worn or rounded center and/orground electrodes indicate excessive wearand can cause hard starting, reduced fueleconomy and misfire during acceleration.This can also damage other secondaryignition components such as spark plugwires, coils and the distributor cap.RECOMMENDATIONS Replace with spark plugsof the same heat range and design.SYMPTOMS Shiny tan or yellow depositssuggest that temperatures have suddenlyincreased under severe loads. Excessive hightemperatures can result in the glazing of thespark plug insulator by allowing fuel andcombustion chamber deposits to melt ratherthan burn off in a normal manner.RECOMMENDATIONS Replace with spark plugsof the correct heat range.THE FIRING END OFTHE PLUG, YOU CANDETERMINE THEOVERALL “HEALTH”OIL FOULEDMECHANICAL DAMAGEOVERHEATEDOF AN ENGINE ANDDIAGNOSE ITSPROBLEMS. CHECKSPARK PLUGSSYMPTOMS Black oily coating can be causedby poor oil control. This usually representsadvanced engine wear and results in acomplete cylinder misfire condition.RECOMMENDATIONS Check for worn valveguides, valve stem seals and piston rings.In some engines, a defective PCV valve cancontribute to this condition.SYMPTOMS Bent and/or broken electrodes andcore nose indicate mechanical damage causedby a foreign object in the combustion chamberor improper reach spark plugs.RECOMMENDATIONS Remove the foreign objectfrom the engine. Check the Mopar Spark Plugscatalog for proper spark plug application andreplace as specified.SYMPTOMS Chalky white insulator with littleor no coloration and extensive electrode wearwhich is possibly blistered or pitted. The shellmay also be discolored from light grayto a dark blue, almost black.RECOMMENDATIONS Verify ignition timing andfuel systems are within specifications and thatcooling and emissions are working properly.Check for correct heat range spark plugs.REGULARLY ANDFOLLOW THEMILEAGE INTERVALSLISTED IN THEOWNER’S MANUAL.ASH DEPOSITSSYMPTOMS Light brown deposits encrustedon the ground and/or center electrodes. Thissituation is caused by oil and/or fuel additives.RECOMMENDATIONS When the deposits arefound on only one side of the spark plug corenose, check the cylinder head (valve stem sealsor valve guides). When they are found on bothsides of the spark plug, check the piston rings.The spark plug is the correct heat range andwas a victim of the engine’s condition, not thecause of it.PRE-IGNITIONSYMPTOMS Spark plug shows signs of beinghot or blistered, and/or has melted center andground electrodes.RECOMMENDATIONS Make sure coolingsystem, spark advance and fuel mixtures areto specifications. Special attention should begiven to the EGR and knock sensor systems.Mis-routing spark plug wires can also lead tocross induction and preignition. Identify causeof preignition and check engine mechanicalcondition before replacing plugs.CARBON FOULEDSYMPTOMS Soft, black, sooty, dry-lookingdeposits indicate a rich air fuel mixture, weakignition or wrong heat range spark plug (toocold). This will result in engine misfire.RECOMMENDATIONS Check for correct plug heatrange. On fuel injected engines, check forsticking injectors, malfunctioning cold startvalves and/or circuits, and for correct fuelpressure. On computer controlled vehicles, the“limp home” computer mode will always resultin a rich condition. It is imperative that youcheck the operation and condition of theon-board computer system. On carburetedvehicles, check choke and choke pulloff, highfloat level and needle and seat condition.Use only MoparSpark Plugs, theoriginal sparkplug used inChrysler, Dodgeand Jeep® vehicles.DETONATIONSYMPTOMS Small black or gray spots will benoticed on the core nose of the spark plug.In cases of severe detonation, insulators maybe cracked and/or chipped.RECOMMENDATIONS Make sure recommendedoctane fuel is being used. Assure properoperation of cooling, emission and computersystems with special attention to EGR and knocksensor systems. Identify cause of detonation andrepair check engine mechanical condition beforereplacing plugs.FUEL ADDITIVESSYMPTOMS Red to purple deposits on oneside of the core nose are an indication of afuel additive. While many of the deposits arenon-conductive and do not contribute to lackof performance, some fuel additives containoctane boosters that leave conductivedeposits on the core nose.RECOMMENDATIONS Care should be takento assure that any fuel additives used arecompatible with engine manufacturer’srecommendations.