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2017 MKC 2.0L Misfire - Rough Idle and P0302 Code

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Mike T. · rep 0 · May 25, 4:27 AM · 1 replies · solved · Question

Vehicle: 2017 Lincoln MKC 2.0L AWD

Hey everyone,

My 2017 Lincoln MKC, 2.0L AWD, has been running really rough lately, especially at idle. It feels like it's shaking more than usual, and sometimes I notice a slight hesitation when accelerating from a stop.

The check engine light came on solid a couple of days ago. I used a basic OBD-II scanner that I have, and it pulled a P0302 code. This indicates a misfire on cylinder 2. I'm wondering if this is a common issue for these MKCs and what steps I should take before heading to a mechanic. Any advice would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:27 AM

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ClearTheCode admin answer:

A P0302 code indicates a misfire detected in cylinder 2. This is a common diagnostic issue, and several factors can cause it. Here's a breakdown of potential causes and steps you can take:

  1. Common Causes for P0302:

    • Spark Plug: A worn, fouled, or improperly gapped spark plug in cylinder 2.
    • Ignition Coil: A faulty ignition coil for cylinder 2. This is a very common culprit for specific cylinder misfires.
    • Fuel Injector: A clogged or malfunctioning fuel injector for cylinder 2, leading to insufficient fuel delivery.
    • Vacuum Leak: A vacuum leak near cylinder 2 or the intake manifold affecting that cylinder's air-fuel mixture.
    • Compression Issue: Less common, but a mechanical issue like a bad valve or piston ring causing low compression in cylinder 2.
    • Wiring: Damaged wiring to the spark plug, coil, or injector.

  2. Diagnostic Steps You Can Take:

    • Check Spark Plug & Coil: If you're comfortable, you can try swapping the ignition coil from cylinder 2 with an adjacent cylinder (e.g., cylinder 1 or 3). Clear the code and drive the vehicle. If the misfire code changes to the new cylinder (e.g., P0301 or P0303), you've likely identified a bad coil. If the code remains P0302, inspect the spark plug in cylinder 2.
    • Listen for Vacuum Leaks: With the engine running, listen for any hissing sounds around the intake manifold.
    • Fuel System Cleaner: A high-quality fuel system cleaner might help if the issue is a slightly clogged injector, but it's not a guaranteed fix.

  3. When to See a Shop:

    • If swapping coils or checking the spark plug doesn't resolve the issue, or if you're uncomfortable performing these steps, it's best to see a qualified mechanic.
    • A professional shop can perform a more thorough diagnosis, including:
      • Advanced scan tool diagnostics to check live data (fuel trims, O2 sensor readings).
      • Fuel pressure tests.
      • Compression tests.
      • Injector pulse tests.
      • Smoke test for vacuum leaks.

Ignoring a misfire can lead to further damage, such as catalytic converter failure, so addressing it promptly is important.

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