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Rough idle & P0301 code on 2016 MDX - Time for new spark plugs?

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Mike T. · rep 0 · May 25, 3:43 AM · 1 replies · solved · Question

Vehicle: 2016 Acura MDX SH-AWD

My 2016 Acura MDX SH-AWD, with just over 105,000 miles, has recently started acting up. I've noticed a rough idle, especially when I'm stopped at a light. The check engine light came on, and when I scanned it, I got a P0301 code, indicating a misfire in cylinder 1.

Given the mileage, I'm wondering if this is a classic sign that it's time for new spark plugs. I've never replaced them before. Is this a job I can realistically do myself in my garage, or is it better left to a professional? What kind of spark plugs should I be looking for, and are there any special tools or tricks for the MDX's engine?

Any guidance would be super helpful!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:43 AM

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ClearTheCode admin answer:

A P0301 code (Cylinder 1 Misfire Detected) combined with a rough idle at 105,000 miles on your 2016 Acura MDX strongly suggests that spark plugs are a very likely culprit. Acura recommends spark plug replacement around 105,000 miles for most of their V6 engines, so you're right on schedule.

Here's a breakdown:

  1. Likely Causes:

    • Worn Spark Plugs: Over time, the electrodes on iridium spark plugs (which your MDX uses) wear down, increasing the gap and requiring more voltage to fire. This can lead to misfires, especially under load or during idle.
    • Faulty Ignition Coil: While less common than plugs at this mileage, a failing ignition coil for cylinder 1 could also cause this. Often, if you replace the spark plug and the misfire persists, swapping the coil with an adjacent cylinder can help confirm if the coil is bad (if the misfire moves).
    • Fuel Injector: A clogged or failing fuel injector for cylinder 1 is another possibility, though less common than plugs/coils for a P030x code.

  2. DIY Spark Plug Replacement: This is a manageable DIY job for a mechanically inclined individual. Here's what you'll need and some tips:

    • Tools: Ratchet, various extensions, spark plug socket (typically 16mm or 5/8"), torque wrench, dielectric grease, anti-seize compound.
    • Spark Plugs: Always use OEM equivalent Iridium spark plugs, such as NGK Iridium IX or Denso Iridium Long Life, which are typically factory-installed. Do not use copper or platinum plugs.
    • Procedure: You'll need to remove the engine cover and potentially some intake components to access all six spark plugs. For the rear bank (cylinders 1, 2, 3), it might be a bit tighter. Label your coil packs and wiring to ensure correct reinstallation. Apply a small amount of anti-seize to the spark plug threads and dielectric grease inside the coil pack boots.
    • Torque: It's crucial to torque the new spark plugs to the manufacturer's specification (usually around 13 lb-ft or 18 Nm for these plugs) to prevent damage to the cylinder head or plugs.

When to See a Shop:

  • If the misfire persists after replacing the spark plugs and checking/swapping ignition coils.
  • If you're uncomfortable working in tight engine bay spaces or lack the necessary tools.
  • If the check engine light returns with different or multiple misfire codes, or other diagnostic trouble codes.
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