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2018 Dodge Charger R/T - P0301 Misfire on Cylinder 1, Rough Idle

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Mike T. · rep 0 · May 22, 5:39 AM · 1 replies · solved · Question

Vehicle: 2018 Dodge Charger R/T

Hey everyone,

I'm having an issue with my 2018 Dodge Charger R/T, 5.7L HEMI. The check engine light came on yesterday, and the car started running a bit rough, especially at idle. It feels like there's a slight shake, and acceleration isn't as smooth as it used to be.

I hooked up my OBD-II scanner, and it pulled a P0301 code, indicating a misfire on Cylinder 1. I haven't done any major work on it recently, just routine oil changes. The car has about 75,000 miles on it.

Has anyone experienced this specific issue with their Charger? What are the common culprits for a P0301 code on these HEMIs? I'm hoping it's something I can tackle myself before taking it to a shop. Any advice on where to start troubleshooting would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:39 AM

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ClearTheCode admin answer:

The P0301 code indicates a misfire detected in Cylinder 1. This means the engine's computer (PCM) has detected that Cylinder 1 is not contributing power as expected. Here's a breakdown of common causes and diagnostic steps:

Common Causes for P0301:

  1. Ignition System:
    • Failing spark plug (worn, fouled, or cracked insulator).
    • Faulty ignition coil pack for Cylinder 1.
    • Damaged spark plug wire (less common on modern engines with coil-on-plug).
  2. Fuel System:
    • Clogged or faulty fuel injector for Cylinder 1.
    • Low fuel pressure (less likely to be cylinder-specific, but possible).
  3. Engine Mechanical:
    • Low compression in Cylinder 1 (e.g., worn piston rings, bent valve, faulty lifter, damaged valve seat).
    • Vacuum leak near Cylinder 1 (less common for single-cylinder misfire).

Diagnostic Steps:

  1. Inspect Spark Plug: Remove the spark plug from Cylinder 1. Look for signs of wear, fouling (oil, carbon, fuel), or damage. If it looks bad, replace it. Consider replacing all plugs if they are due for maintenance.
  2. Swap Ignition Coil: To determine if the coil pack is faulty, swap the ignition coil from Cylinder 1 with a coil from a different cylinder (e.g., Cylinder 3). Clear the code and drive the vehicle. If the misfire moves to Cylinder 3 (P0303), then the coil pack is the issue.
  3. Swap Fuel Injector: If the coil swap doesn't identify the problem, you can try swapping the fuel injector from Cylinder 1 with one from another cylinder. Again, clear the code and drive. If the misfire moves, the injector is faulty.
  4. Check for Vacuum Leaks: While less likely for a single cylinder, visually inspect vacuum lines and intake manifold gaskets around Cylinder 1 for cracks or disconnections.
  5. Compression Test: If the above steps don't resolve the issue, perform a compression test on Cylinder 1 and compare it to other cylinders. Significantly lower compression indicates an internal engine mechanical problem.

When to See a Shop:

  • If you've performed the basic diagnostic swaps (coil, injector) and the misfire persists on Cylinder 1, or if you're uncomfortable performing these steps yourself.
  • If a compression test reveals low compression in Cylinder 1, as this indicates a more serious internal engine issue requiring professional repair.
  • If the check engine light is flashing, which indicates a severe misfire that can damage the catalytic converter, you should stop driving immediately and have it towed to a shop.
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