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2016 Lancer Misfire and Rough Idle - P0301 Code

0

Mike T. · rep 0 · May 25, 4:06 AM · 1 replies · solved · Question

Vehicle: 2016 Mitsubishi Lancer ES

Hey guys,

My 2016 Mitsubishi Lancer ES (2.0L engine) with about 90,000 miles on it has developed a really rough idle, and I'm pretty sure it's misfiring. The check engine light came on, and when I scanned it, I got a P0301 code, which points to a misfire on cylinder 1. The car feels sluggish, especially when accelerating, and sometimes it even shakes a bit at stoplights.

I've already checked the spark plug on cylinder 1, and it looked okay, but I haven't replaced it yet. What's the usual culprit for a P0301 code on these Lancers? Could it be a bad coil pack, or something more serious like an injector?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:06 AM

0

ClearTheCode admin answer:

The P0301 diagnostic trouble code (DTC) indicates a misfire detected in cylinder #1 of your 2016 Mitsubishi Lancer. This is a common issue with several potential causes, and it's good you've already identified the specific cylinder.

Potential Causes for P0301:

  1. Ignition System:
    • Faulty Spark Plug: Even if it 'looks' okay, a worn or fouled spark plug can cause misfires. Given your mileage, it's a prime suspect if they haven't been replaced recently.
    • Bad Ignition Coil: The ignition coil for cylinder #1 could be failing, providing insufficient spark. This is a very common cause of single-cylinder misfires.
    • Worn Spark Plug Wire (if applicable): While many modern engines use coil-on-plug, if your Lancer has wires, a damaged one could be the culprit.
  2. Fuel System:
    • Clogged or Faulty Fuel Injector: An injector that is not delivering enough fuel, or spraying incorrectly, to cylinder #1 can cause a misfire.
    • Low Fuel Pressure: Less likely for a single cylinder, but overall low fuel pressure can affect all cylinders unevenly.
  3. Engine Mechanical:
    • Low Compression: Issues like a burnt valve, worn piston rings, or a head gasket leak on cylinder #1 can lead to low compression and misfires. This is typically a more serious issue.
    • Vacuum Leak: A vacuum leak near cylinder #1 could lean out the air-fuel mixture, causing a misfire.

Troubleshooting Steps:

  1. Swap Components: The easiest diagnostic step is to swap the ignition coil from cylinder #1 with one from a different cylinder (e.g., cylinder #2). Clear the code and drive the car. If the misfire moves to cylinder #2 (P0302), then the coil is bad. If it stays at P0301, the coil is likely fine.
  2. Replace Spark Plugs: If the coils check out, consider replacing all spark plugs, especially if they are due for maintenance. If the issue persists, focus back on cylinder #1.
  3. Inspect Fuel Injector: If the misfire remains on cylinder #1 after swapping coils and checking plugs, the next step is to test or swap the fuel injector for cylinder #1. A mechanic can test its spray pattern and resistance.
  4. Compression Test: If all else fails, a compression test on cylinder #1 is necessary to rule out internal engine mechanical problems.

When to See a Shop:

If swapping coils and replacing spark plugs doesn't resolve the P0301 code, or if you're uncomfortable performing these steps, it's best to take your Lancer to a qualified mechanic. They have specialized tools to test fuel injectors and perform compression tests accurately. Driving with a persistent misfire can damage your catalytic converter over time.

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