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2018 Escalade 6.2L Misfire - Time for new spark plugs and coils?

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Mike T. · rep 0 · May 25, 2:54 AM · 1 replies · solved · Question

Vehicle: 2018 Cadillac Escalade ESV 6.2L

Hey fellow Cadillac owners,

My 2018 Cadillac Escalade ESV with the 6.2L V8 just threw a check engine light, and I'm experiencing a noticeable rough idle and some hesitation under acceleration. The OBD-II scanner is showing P0304 (Cylinder 4 Misfire Detected) and P0300 (Random/Multiple Cylinder Misfire Detected).

The truck has about 85,000 miles on it, and I don't believe the spark plugs have ever been changed. Is it time for a full set of plugs and maybe even the ignition coils? I've heard these 6.2L engines can be particular.

Any tips on brand recommendations for plugs and coils, or if this is a relatively straightforward DIY job for someone with moderate mechanical skills? Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:54 AM

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ClearTheCode admin answer:

Experiencing misfires and a check engine light on your 2018 Cadillac Escalade ESV at 85,000 miles, especially with the 6.2L V8, strongly suggests it's time for spark plug and potentially ignition coil replacement. The P0304 code specifically points to Cylinder 4, while P0300 indicates a general misfire condition.

Causes of Misfires:

  • Worn Spark Plugs: Over time, the electrodes on spark plugs wear down, increasing the voltage required to fire and leading to inefficient combustion.
  • Failing Ignition Coils: Ignition coils provide the high voltage to the spark plugs. A failing coil (especially on Cylinder 4, given your P0304 code) can't deliver adequate spark.
  • Fuel Delivery Issues: Clogged fuel injectors or low fuel pressure can also cause misfires, though less common to be cylinder-specific without other codes.
  • Vacuum Leaks: Leaks in the intake manifold or vacuum lines can lead to lean conditions and misfires.

Recommended Action Steps:

  1. Diagnose Cylinder 4: Given the P0304 code, focus initial diagnosis on Cylinder 4. You can try swapping the ignition coil from Cylinder 4 to another cylinder (e.g., Cylinder 2). If the misfire code moves to Cylinder 2 (P0302), then the coil is faulty. If it stays on Cylinder 4, the plug or injector is more likely the culprit.
  2. Replace Spark Plugs: At 85,000 miles, it's definitely time for a full set of spark plugs. For the 6.2L V8, use OEM AC Delco Iridium plugs (part number 41-110 or equivalent). These are designed for long life and optimal performance.
  3. Consider Ignition Coils: If you confirm a faulty coil, replace it. Many owners opt to replace all coils if one fails around this mileage, as others may soon follow. Stick with OEM AC Delco or a reputable aftermarket brand like Delphi.
  4. Inspect Wires: While less common on modern coil-on-plug systems, inspect any wiring harnesses to the coils for damage.
  5. Clear Codes and Test Drive: After replacement, clear the diagnostic codes and take the Escalade for a test drive to ensure the issue is resolved and no new codes appear.

When to See a Shop:

  • Persistent Misfires: If replacing plugs and coils doesn't resolve the issue, or if the misfire moves to multiple cylinders without a clear cause.
  • Difficulty Accessing Plugs/Coils: While generally a DIY-friendly job, the 6.2L engine bay can be tight. If you're uncomfortable with the access or tools required.
  • Suspected Fuel System Issues: If diagnostics point to fuel injectors (e.g., P0204 for injector circuit malfunction) or fuel pressure problems, which require specialized tools and knowledge.
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