{"product_id":"ignition-coil-and-iridium-spark-plugs-for-gmc-envoy-xl-2002-2005-4-2l","title":"Ignition Coil and Iridium Spark Plugs for GMC Envoy XL (2002-2005) 4.2L","description":"\u003ch2\u003eDirect-Replacement Ignition Coil and Iridium Spark Plug Kit for 2002-2005 GMC Envoy XL\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhat it Does:\u003c\/strong\u003e The Ignition Coil and Iridium Spark Plug Kit restores factory secondary ignition voltage and combustion efficiency on the 2002-2005 GMC Envoy XL to eliminate engine misfires, rough idle, and unburned fuel dumping.\u003c\/p\u003e\n\n\u003ch3\u003eThe Stock GMC Envoy XL Secondary Ignition Breakdown\u003c\/h3\u003e\n\u003cp\u003eThe factory coil-on-plug assemblies on the \u003cstrong\u003eGMT368\u003c\/strong\u003e platform sit directly atop the cylinder head inside recessed plug wells, exposing them to continuous high-temperature thermal cycling. Over time, the OEM coil potting epoxy hardens and develops micro-fractures, causing internal dielectric breakdown and secondary winding arcing under load. Simultaneously, aged factory spark plugs suffer center electrode erosion, widening the spark gap past factory specifications. This enlarged gap elevates the kilovolt demand on the aging ignition coils, accelerating coil failure and throwing diagnostic trouble codes P0300 through P0306 across the \u003cstrong\u003eAtlas LL8\u003c\/strong\u003e inline-six engine.\u003c\/p\u003e\n\n\u003ch3\u003eThe Engineering Solution\u003c\/h3\u003e\n\u003cp\u003eThis direct-fit kit resolves ignition dropouts by pairing high-output pencil coils with precision-engineered iridium spark plugs matching interchange numbers \u003cstrong\u003eUF303\u003c\/strong\u003e and \u003cstrong\u003e68070492AB\u003c\/strong\u003e. The replacement coils feature impact-resistant, high-dielectric PBT housings, copper core windings, and high-temp silicone boots that isolate secondary voltage and block flashover. Paired with fine-wire iridium center electrodes, the spark plugs resist electrical erosion, lower required ignition voltage, and maintain a consistent flame kernel propagation under heavy throttle transitions and sustained highway loads.\u003c\/p\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable width=\"100%\" style=\"border-collapse: collapse; border: 1px solid #e0e0e0; font-size: 14px; margin-bottom: 20px;\"\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eFitment\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e2002-2005 GMC Envoy XL\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eEngine \/ Chassis\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e4.2L Vortec Inline-6 (LL8) \/ GMT368\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background-color: #f9f9f9;\"\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eStock Output\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e275 hp \/ 275 lb-ft\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth style=\"padding:10px; text-align: left; border: 1px solid #e0e0e0;\"\u003eReplaces OEM Part #\u003c\/th\u003e\n\u003ctd style=\"padding:10px; border: 1px solid #e0e0e0;\"\u003e68070492AB, UF303, KIN119942TOP\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eCompatibility\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e2002-2005 GMC Envoy XL SLE 4.2L L6\u003c\/li\u003e\n  \u003cli\u003e2002-2005 GMC Envoy XL SLT 4.2L L6\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this fit the GMT368 Envoy XL?\u003c\/strong\u003e\u003cbr\u003e Yes, this is a direct fit for the 2002-2005 GMC Envoy XL equipped with the \u003cstrong\u003eAtlas LL8\u003c\/strong\u003e 4.2L Vortec engine.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre these spark plugs pre-gapped?\u003c\/strong\u003e\u003cbr\u003e Yes, the iridium plugs are pre-set to factory specifications, though verifying proper gap with a feeler gauge prior to installation is recommended.\u003c\/p\u003e\n\n\u003ch3\u003eThe GMC Towing \u0026amp; Utility Standard\u003c\/h3\u003e\n\u003cp\u003eEngineered for full-size family hauling and sustained trailer pulling, the extended \u003cstrong\u003eGMT368\u003c\/strong\u003e chassis demands continuous, uninterrupted spark delivery to safeguard catalytic converter life and maintain stable air-fuel ratios under load.\u003c\/p\u003e","brand":"VelocityMax","offers":[{"title":"Default Title","offer_id":50594266382584,"sku":"DS-E3EOBCST5","price":99.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0800\/1290\/2648\/files\/ignition-coil-and-iridium-spark-plugs-for-gmc-envoy-xl-2002-2005-4-2l-1.jpg?v=1790058564","url":"https:\/\/performancechiptuning.com\/products\/ignition-coil-and-iridium-spark-plugs-for-gmc-envoy-xl-2002-2005-4-2l","provider":"Performance Chip Tuning","version":"1.0","type":"link"}