Ignition Coil and Iridium Spark Plugs for Jeep Wrangler (2000-2006) 4.0L

Direct-Fit Ignition Coil Rail and Iridium Spark Plug Kit for 2000-2006 Jeep Wrangler

What it Does: Restores factory secondary ignition performance and eliminates cylinder misfires on the 4.0L inline-six by replacing the complete ignition cassette and worn spark plugs with heavy-duty components.

The Stock Wrangler Ignition Rail Thermal Breakdown

The factory distributorless ignition system on the 4.0L AMC inline-six utilizes a solid coil rail assembly mounted directly above the exhaust and intake manifolds. Constant thermal cycling and severe engine bay heat soak degrade the internal resin potting compound, leading to primary and secondary winding breakdown. Over time, brittle silicone plug boots and internal conductor fatigue cause high-voltage dielectric arcing, hesitation under load, rough idling, and persistent P0300–P0306 misfire trouble codes.

The Engineering Solution

This replacement kit features a reinforced one-piece coil rail housing three dual-output wasted-spark coil modules encapsulated in high-dielectric epoxy to resist thermal degradation and structural cracking. Upgraded silicone boots and corrosion-resistant stainless-steel contact springs prevent voltage leakage under high-load conditions. Paired with six fine-wire iridium spark plugs, the assembly reduces the secondary voltage required to bridge the gap, providing consistent flame kernel development, enhanced fouling resistance, and reliable combustion stability across all RPM ranges.

Technical Specifications

Compatibility

• 2000-2006 Jeep Wrangler TJ (4.0L Inline-6 AMC 242)
• 2004-2006 Jeep Wrangler LJ Unlimited (4.0L Inline-6 AMC 242)
• Direct interchange for OE numbers: UF296, UF-296, 56041476AA, 56041476AB, 5C1181, 5C1182, C1230, C1263, 56041019, IC399, E239

The Jeep Off-Road Durability Standard

Engineered to handle severe trail vibration, sustained low-RPM crawl loads, and high under-hood temperatures, this ignition kit delivers reliable firing performance and throttle response required for off-camber operation and heavy towing demands.