🔧 Grand Cherokee - Ignition Coil Replacement

Replacing the ignition coils on your Grand Cherokee is a straightforward repair that can fix misfires, rough idle, hesitation, and check-engine light codes related to ignition performance. The 5.7L V8 uses coil-on-plug ignition coils, meaning each coil sits directly on top of a spark plug and sends spark to that cylinder.

Difficulty Level: Beginner | Estimated Time: 1-2 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool completely before starting; the exhaust manifolds and cylinder heads can burn you.
• ⚠️ Disconnecting the negative battery cable is recommended to avoid accidental short circuits while unplugging ignition connectors.
• ⚠️ Work on one coil at a time if you are new to this, so connectors and parts do not get mixed up.
• ⚠️ Do not pull on wiring harnesses; pull on the connector body only.
• ⚠️ Ignition coils can create high voltage when operating. Never unplug coils with the engine running.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 8mm socket
• 3/8-inch drive ratchet
• 3/8-inch drive 6-inch extension
• Torque wrench inch-pound 20-200 in-lb
• Flat-blade screwdriver
• Plastic trim removal tool
• Needle-nose pliers
• Dielectric grease packet
• Safety glasses
• Nitrile gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Ignition coil - Qty: 1-8
• Ignition coil mounting bolt - Qty: As needed
• Electrical contact cleaner - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park your Grand Cherokee on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool until it is comfortable to touch.
• Use a 10mm socket to loosen the negative battery terminal, then move the cable aside so it cannot spring back onto the battery post.
• If replacing only one coil, identify the correct cylinder before removing parts. The 5.7L HEMI cylinder layout is: driver side front-to-back 1-3-5-7, passenger side front-to-back 2-4-6-8.
• A coil-on-plug coil is the black plastic ignition part bolted above the spark plug tube.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the Engine Cover

• Use both hands to lift the plastic engine cover straight upward from its rubber mounting grommets.
• If it feels stuck, use a plastic trim removal tool to gently lift near each mounting point.
• Set the cover aside where it will not be stepped on.
• Lift upward, not sideways.

Step 2: Locate the Ignition Coils

• Look along the top outer edges of both cylinder heads for the ignition coils.
• Each coil has an electrical connector and a small mounting bolt.
• If replacing all coils, plan to do one coil at a time so the job stays simple.

Step 3: Unplug the Ignition Coil Connector

• Put on safety glasses and nitrile gloves.
• Use a flat-blade screwdriver to gently lift the red connector lock tab if equipped.
• Press the connector release tab with your thumb or a flat-blade screwdriver.
• Pull the connector straight off the ignition coil by holding the connector body.
• If the connector is stubborn, use needle-nose pliers only on the connector body, not the wires.
• Never pull the wires.

Step 4: Remove the Ignition Coil Bolt

• Use an 8mm socket, 3/8-inch drive ratchet, and 6-inch extension to remove the ignition coil mounting bolt.
• Place the bolt in a small safe spot so it does not fall into the engine bay.
• If the bolt is damaged or rusty, replace it with a new ignition coil mounting bolt.

Step 5: Remove the Old Ignition Coil

• Grip the ignition coil firmly by the top body.
• Twist it gently left and right to loosen the rubber boot from the spark plug.
• Pull the ignition coil straight upward and out of the spark plug tube.
• If the boot sticks, keep twisting gently while pulling upward.
• Inspect the old coil boot for oil, cracks, white tracking marks, or tears.
• Tracking marks look like thin burned lines and can mean spark was leaking through the boot.

Step 6: Inspect the Spark Plug Tube Area

• Use a flashlight to look into the spark plug tube.
• If you see engine oil inside the tube, the coil may fail again because oil can damage the boot.
• If the electrical connector has dirt or corrosion, use electrical contact cleaner and let it dry fully.
• Do not spray cleaner into the open spark plug tube.

Step 7: Prepare the New Ignition Coil

• Apply a very small amount of dielectric grease inside the end of the new coil boot.
• Dielectric grease is a non-conductive silicone grease that helps seal moisture out of the boot.
• Do not pack the boot full of grease; a thin film is enough.
• A pea-size amount is plenty.

Step 8: Install the New Ignition Coil

• Push the new ignition coil straight down into the spark plug tube.
• Press firmly until you feel the boot seat onto the spark plug.
• Line up the coil mounting hole with the bolt hole in the valve cover area.
• Start the mounting bolt by hand first to avoid cross-threading.

Step 9: Tighten the Ignition Coil Bolt

• Use an 8mm socket, 3/8-inch drive extension, and torque wrench to tighten the ignition coil mounting bolt.
• Torque to 7 Nm (62 in-lbs)
• Do not overtighten; the mounting area can crack if forced.

Step 10: Reconnect the Electrical Connector

• Push the ignition coil connector straight onto the coil until it clicks.
• Push the red connector lock tab back into place if equipped.
• Gently tug the connector body to confirm it is locked.

Step 11: Repeat for Additional Coils

• If replacing more than one ignition coil, repeat Steps 3 through 10 for each coil.
• Use the same 8mm socket, ratchet, extension, and torque wrench for each coil bolt.
• Keep working one coil at a time to prevent confusion.

Step 12: Reinstall the Engine Cover

• Align the engine cover over its rubber mounting grommets.
• Press straight down with both hands until the cover seats securely.
• Make sure no wiring is trapped under the cover.

Step 13: Reconnect the Battery

• Place the negative battery cable back onto the battery post.
• Use a 10mm socket to tighten the terminal clamp snugly.
• Torque to 5 Nm (44 in-lbs)
• Do not overtighten the battery terminal clamp.

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✅ After Repair

• Start the engine and let it idle for 1-2 minutes.
• Listen for smooth idle and confirm there are no new ticking, arcing, or popping sounds.
• If a check-engine light was on for a misfire, it may turn off after several drive cycles, or it can be cleared with a scan tool.
• Take a short test drive and check for hesitation, shaking, or flashing check-engine light.
• If the check-engine light flashes during the test drive, stop driving and recheck the coil connector and installation.
• Some idle relearn behavior may occur after battery disconnect; let the engine idle with accessories off for a few minutes.

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💰 DIY vs Shop Cost

Shop Cost: $180-$750 depending on how many coils are replaced

DIY Cost: $35-$400 depending on coil quantity and brand

You Save: $145-$350 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 0.5-1.5 hours.

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