<h2>Direct-Replacement Ignition Coil and Iridium Spark Plug Service Kit for 2015-2018 BMW X4</h2> <p><strong>What it Does:</strong> Replaces degraded factory ignition coils and worn plugs to eliminate high-boost misfires, stabilize idle fluctuations, and restore precise secondary ignition voltage across all six cylinders.</p> <h3>The Stock X4 Ignition System Fatigue</h3> <p>The turbocharged inline-six in the F26 platform generates intense thermal loads and elevated cylinder pressures. Over time, OEM coil housings suffer dielectric breakdown and thermal fatigue, causing micro-arcing and internal winding resistance shifts. Simultaneously, standard plug electrodes erode under boost, widening the gap and forcing the secondary ignition circuit to demand higher breakdown voltage. This manifests as cold-start stuttering, hesitation under load, and DME misfire trouble codes.</p> <h3>The Engineering Solution</h3> <p>This comprehensive service pack pairs six high-dielectric coil assemblies with matched fine-wire iridium spark plugs. The coils feature reinforced internal copper windings, heat-resistant silicone boots, and factory-matched blade terminals that resist thermal saturation. The iridium plugs utilize a laser-welded fine-wire center electrode and nickel-alloy ground design to reduce voltage requirements, lower quench effects, and ensure stable flame-front propagation under peak boost.</p> <h3>Technical Specifications</h3> <table width="100%" style="border-collapse: collapse; border: 1px solid #e0e0e0; font-size: 14px;"> <tr style="background-color: #f9f9f9;"> <td style="padding:8px;"><strong>Fitment</strong></td> <td style="padding:8px;">2015-2018 BMW X4 (3.0L L6)</td> </tr> <tr> <td style="padding:8px;"><strong>Engine / Chassis</strong></td> <td style="padding:8px;">N55 Turbocharged I6 / F26</td> </tr> <tr style="background-color: #f9f9f9;"> <td style="padding:8px;"><strong>Stock Output</strong></td> <td style="padding:8px;">300–355 hp / 300–343 lb-ft (Approx)</td> </tr> <tr> <td style="padding:8px;"><strong>Part Number</strong></td> <td style="padding:8px;">UF515, UF-515, UF522, UF-522</td> </tr> </table> <h3>Compatibility</h3> <ul> <li>2015-2018 BMW X4 xDrive35i (3.0L Turbo Inline-6 N55)</li> <li>2016-2018 BMW X4 M40i (3.0L Turbo Inline-6 N55)</li> </ul> <h3>The BMW Precision Standard</h3> <p>Engineered to meet stringent European onboard diagnostic tolerances, this matched ignition kit ensures factory dwell compatibility, smooth idle, and error-free operation without triggering DME shadow codes or check engine lights.</p>