2021 Jeep Cherokee 2.4L Spark Plug Replacement — Tigershark MultiAir, NGK ILKR8H8, Step-by-Step DIY Guide

I've replaced spark plugs on the 2021 Jeep Cherokee 2.4L more than a few times, and it's one of those jobs that looks harder than it is. The Tigershark MultiAir engine has individual coil-on-plug ignition with four plugs — all accessible from the top of the engine once you remove the engine cover. No need to go underneath, no need to remove the intake manifold. Plan for 45–60 minutes. Dealers quote $180–$260 for this service. Your parts cost: $35–$45.

The 2.4L Tigershark uses a unique MultiAir hydraulic valve actuation system that's sensitive to fuel wash-down — a condition that can occur when spark plugs are worn and misfires develop. Staying on top of the spark plug interval protects the MultiAir system.

Engine and Spark Plug Specs

Item	Spec
Engine	2.4L ED6 Tigershark MultiAir II inline-4
OEM spark plug	NGK ILKR8H8 (iridium)
Mopar equivalent	68190678AA
Gap	Pre-gapped at 0.028" — do not adjust
Plug torque	13 lb-ft (18 Nm)
COP coil bolt	8mm hex; 7.4 lb-ft (10 Nm)
Replacement interval	100,000 miles (OEM iridium spec)

The NGK ILKR8H8 is an iridium plug — it's pre-gapped at the factory. Don't adjust the gap. The iridium center electrode is fragile and any contact with a gap tool can crack it.

Tools and Parts List

• 4x NGK ILKR8H8 spark plugs (or Mopar 68190678AA)
• 5/8" spark plug socket (rubber insert to hold plug)
• 3/8" ratchet + 6" extension
• 8mm socket (coil hold-down bolts)
• Torque wrench (5–20 lb-ft range)
• Dielectric grease
• Compressed air or rag (for cleaning plug wells)
• Penetrating oil (just in case)

Cost Comparison

Item	DIY Cost	Shop Cost
4x NGK ILKR8H8 plugs	$28–$36	—
Dielectric grease	$3	—
Total parts	~$31–$39	—
Labor	$0	$150–$220
Total	~$31–$39	$180–$260

You save $140–$220 on this one job. With a 100,000-mile replacement interval, you'll only do this a few times in the vehicle's life — but each time, you're saving over $150.

Step-by-Step Spark Plug Replacement

1. Let the Engine Cool Completely

This job must be done on a cold engine. Aluminum spark plug threads seize when hot, and the Tigershark MultiAir head is particularly sensitive to this. Do this job first thing in the morning, or wait 3+ hours after the last drive.

2. Remove the Engine Cover

The 2021 Jeep Cherokee 2.4L has a plastic engine cover that snaps off. Grip it firmly from the sides and pull up — it clips onto four or six rubber mounts. Set it aside.

3. Clean the Plug Wells

Use compressed air to blow out any dirt, leaves, or debris that's accumulated around the coil packs. The Cherokee's engine bay can collect debris around the firewall-side coils. Blowing this out before you pull coils prevents contamination from entering the combustion chamber.

4. Remove the COP Coils (One at a Time)

Work one cylinder at a time — this prevents mixing up coil positions.

Each coil pack has:

• One electrical connector (press the tab, pull straight out)
• One 8mm hold-down bolt

Remove the 8mm bolt, then pull the coil pack straight up and out of the plug well. The coil boot will release from the spark plug below — pull with steady, straight upward force. If it feels stuck, twist slightly before pulling.

5. Remove the Spark Plug

With the plug socket and extension, break the plug loose counterclockwise. Spin it out by hand once loose. Inspect the old plug: a tan/gray electrode indicates normal combustion. Black sooty deposits indicate richness or oil burning. White/blistered ceramic indicates overheating.

6. Check the Plug Well

Before installing the new plug, look down the well with a flashlight. Any signs of coolant? Any oil accumulation? On the Tigershark, oil in the plug wells can indicate a leaking valve cover gasket — a separate repair but worth catching now.

7. Install the New Plug

Thread the new NGK ILKR8H8 in by hand until finger-tight. Don't cross-thread it. The plug threads are 14mm into an aluminum head — cross-threading requires a helicoil repair. Take your time getting it started.

Once hand-tight, torque to 13 lb-ft (18 Nm).

8. Apply Dielectric Grease and Reinstall the Coil

Apply a small amount of dielectric grease to the inside of the coil boot — this prevents the boot from sticking to the plug next time and improves the electrical connection. Don't apply it to the plug's terminal itself.

Reinstall the coil pack, press it down until you feel it seat on the plug, then reinstall the 8mm hold-down bolt. Torque to 7.4 lb-ft (10 Nm). Reconnect the electrical connector until it clicks.

9. Repeat for All Four Cylinders

Complete cylinders 2, 3, and 4 the same way. The 2.4L Tigershark layout is a straight-4 — all four plugs are in a row, all equally accessible from the top.

10. Reinstall the Engine Cover and Start the Engine

Snap the engine cover back onto its mounts. Start the Cherokee and let it idle. Listen for any misfires (rough idle, hesitation). If you have a code reader, check for any P030X codes — a misfire code after a plug swap usually means a coil boot that isn't fully seated.

MultiAir System Note

The Tigershark MultiAir system uses oil pressure to actuate intake valves. Misfires cause raw fuel wash-down that can contaminate the MultiAir oil control valves. If your Cherokee has been misfiring before this job, monitor for any MultiAir-related codes after the plug replacement. The OwnerDrop diagnostics guide has a walkthrough for reading and clearing OBDII codes on the Cherokee.

Also check the OwnerDrop maintenance schedules guide for the full Cherokee 2.4L service interval chart — the spark plugs at 100k are just one of several items due in that range.

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