2018 Challenger Scat Pack Misfire and Rough Idle - CEL On

ClearTheCode admin answer:

A P0301 code, indicating a misfire on cylinder 1, is a common issue that can have several root causes in your 2018 Dodge Challenger R/T Scat Pack's 6.4L Hemi engine. Addressing it promptly is important to prevent further damage, especially to the catalytic converter if the misfire is severe and persistent.

Here are the typical steps and potential causes to investigate:

1. Check Spark Plugs and Wires/Coils:

   • Cause: A worn, fouled, or incorrectly gapped spark plug in cylinder 1 is a primary suspect. Also, inspect the ignition coil pack for that cylinder for any cracks, corrosion, or signs of failure. If your vehicle uses spark plug wires, check those too, but modern Hemi engines typically use coil-on-plug.
   • Action: You can try swapping the coil pack from cylinder 1 to another cylinder (e.g., cylinder 3) and see if the misfire code follows the coil (e.g., changes to P0303). This helps isolate if the coil is the problem.

2. Inspect Fuel Injector:

   • Cause: A clogged, faulty, or failing fuel injector for cylinder 1 can prevent it from delivering the correct amount of fuel, leading to a misfire. Carbon buildup is a common culprit.
   • Action: Listen for the clicking sound of the injector with a mechanic's stethoscope or a long screwdriver. You can also have a shop perform a fuel injector balance test.

3. Look for Vacuum Leaks:

   • Cause: An unmetered air leak near cylinder 1's intake manifold or vacuum lines can lean out the air/fuel mixture, causing a misfire.
   • Action: Visually inspect all vacuum lines and intake manifold gaskets around cylinder 1 for cracks or disconnections. A smoke test can definitively identify leaks.

4. Check Engine Compression:

   • Cause: In more severe cases, low compression in cylinder 1 due to issues like a worn piston ring, bent valve, or blown head gasket can cause a misfire.
   • Action: This requires a compression test, which is best done by a professional.

When to See a Shop:

• If the check engine light is flashing, this indicates a severe misfire that could be actively damaging your catalytic converter. Drive as little as possible and get it to a shop immediately.
• If basic checks like swapping coils or inspecting plugs don't resolve the issue, or if you're uncomfortable performing these diagnostics yourself.
• If you suspect a fuel injector issue, vacuum leak that's hard to find, or a compression problem, professional diagnostic tools and expertise will be necessary.