Ignition Coil + Spark Plugs for Subaru Forester (1998) 2.5L

Direct-Replacement Ignition Coil and Spark Plug Kit for Subaru Forester (SF)

What it Does: The Ignition Coil and Spark Plug Kit restores factory secondary ignition voltage and combustion efficiency on the 1998 Subaru Forester to eliminate misfires and rough idling under load.

The Stock Subaru Forester Thermal Breakdown and Misfires

The first-generation SF Forester positions its single coil pack centrally atop the horizontally opposed boxer engine. Over decades of service, intense under-hood heat soak degrades the factory epoxy potting and internal windings of the coil. Micro-fractures develop along the housing, inducing high-voltage arcing to the engine block under heavy acceleration. Concurrently, factory spark plugs suffer electrode erosion and widening gaps, forcing the compromised coil pack to generate higher strike voltages than designed. This cascading failure causes hesitation, cylinder misfires (P0300–P0304 DTCs), unburned fuel washdown into the catalytic converter, and noticeable fuel economy drops.

The Engineering Solution

This refresh package replaces aged secondary ignition components with an OE-matched ignition coil pack and four precision-gapped spark plugs. The coil housing utilizes high-dielectric epoxy resin to resist internal insulation breakdown and eliminate high-voltage tracking under thermal cycles. Matched copper-core spark plugs provide consistent flame-front kernel propagation within the pent-roof combustion chamber of the naturally aspirated EJ25D, preventing spark blow-out while matching factory heat ranges. Installing refreshed coils and plugs simultaneously equalizes cylinder impedance and restores nominal primary and secondary coil resistance.

Technical Specifications

Compatibility

• 1998 Subaru Forester Base 2.5L H4 Gas (EJ25D)
• 1998 Subaru Forester L 2.5L H4 Gas (EJ25D)
• 1998 Subaru Forester S 2.5L H4 Gas (EJ25D)

Frequently Asked Questions

Does this fit the SF Chassis Forester?

Yes, this is a direct fit for the 1998 Subaru Forester equipped with the EJ25D DOHC naturally aspirated engine.

Are new spark plug high-tension leads included in this package?

No, this service kit includes the central coil pack and four spark plugs; reuse or inspect your existing plug wires for dielectric breakdown.

The Subaru Boxer Standard

Maintain proper flame propagation and boxer-four throttle response across all weather conditions with components engineered to resist the severe vibration and heat cycles unique to horizontal engine configurations.