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2022 Corsair Misfire on Cylinder 3 - P0303 and Rough Idle

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

Vehicle: 2022 Lincoln Corsair AWD 2.0L EcoBoost

Hello everyone,

I'm experiencing a worrying issue with my 2022 Lincoln Corsair AWD, which has the 2.0L EcoBoost engine and just hit 35,000 miles. Yesterday, while driving, the Check Engine Light started flashing, and the engine developed a very noticeable rough idle and loss of power. It feels like the car is shaking.

I managed to get it home and scanned it with my OBD-II reader. It's showing a P0303 code, which indicates a misfire on Cylinder 3. I haven't done any recent maintenance besides routine oil changes. The car has always run smoothly until now.

Could this be a bad spark plug or ignition coil already at this mileage? Or something else I should look into? Any advice on troubleshooting would be great.

✓ Accepted solution

ClearTheCode Admin

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

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ClearTheCode admin answer:

A flashing Check Engine Light, rough idle, and a P0303 code on your 2022 Lincoln Corsair indicate an active and potentially damaging misfire on Cylinder 3. A flashing CEL means the misfire is severe enough to cause catalytic converter damage, so it's important to address this promptly.

Here's a breakdown of common causes and diagnostic steps:

  1. Understanding P0303:

    • Cause: P0303 specifically means the Powertrain Control Module (PCM) has detected a misfire (lack of combustion) in Cylinder 3. This can be due to a problem with spark, fuel, or compression.

  2. Common Causes for Misfire:

    • Ignition Coil (Most Common): A failing ignition coil is a very frequent cause of misfires, especially on a single cylinder. The coil provides the high voltage for the spark plug.
    • Spark Plug: While 35,000 miles is a bit early for a spark plug to completely fail, it's possible for one to be faulty or fouled, preventing proper ignition.
    • Fuel Injector: A clogged, dirty, or failing fuel injector on Cylinder 3 would prevent it from delivering the correct amount of fuel, leading to a lean misfire.
    • Compression Issue: Less common, but a problem like a leaky valve, worn piston rings, or a blown head gasket can cause low compression in a cylinder, preventing it from firing correctly.
    • Vacuum Leak: A vacuum leak near Cylinder 3 could cause a lean condition and misfire, though usually, this would affect multiple cylinders or trigger a P0171/P0174 code first.

  3. Troubleshooting Steps (DIY if comfortable, otherwise professional):

    • The 'Swap Test' (for Coil and Plug): This is the most common diagnostic for a single-cylinder misfire.
      1. Swap Ignition Coil: Move the ignition coil from Cylinder 3 to a different cylinder (e.g., Cylinder 1). Clear the code. Drive the car gently to see if the misfire moves to the new cylinder (e.g., P0301). If it does, the coil is bad.
      2. Swap Spark Plug: If the misfire doesn't move, next swap the spark plug from Cylinder 3 to another cylinder. Clear the code and test. If the misfire moves, the spark plug is bad.
    • Listen for Injector: Use a stethoscope or a long screwdriver to listen to the fuel injector on Cylinder 3. You should hear a distinct clicking sound. Compare it to other injectors.

When to See a Shop: If the swap test doesn't pinpoint the coil or plug, or if you're not comfortable performing these steps, it's best to take your Corsair to a Lincoln dealership or a trusted independent mechanic. They have advanced diagnostic equipment to:

  • Perform a fuel injector test.
  • Conduct a compression test on Cylinder 3.
  • Use a scope to check for other electrical issues.
  • Diagnose any potential PCM-related problems.

Driving with a flashing CEL and a severe misfire can lead to expensive catalytic converter damage, so prompt diagnosis and repair are crucial.

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