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2018 Challenger R/T Hemi Misfire and Rough Idle - Check Engine Light On

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Mark S. · rep 0 · May 22, 5:39 AM · 1 replies · solved · Question

Vehicle: 2018 Dodge Challenger R/T

Hey everyone, I'm having some trouble with my 2018 Dodge Challenger R/T, 5.7L Hemi. Lately, it's developed a really rough idle, especially when I first start it up in the morning. It feels like it's shaking more than usual, and the engine sounds a bit off.

The check engine light came on yesterday, and it's staying on. When I try to accelerate, it feels like there's a noticeable loss of power, and sometimes it even stutters a bit. It's not consistent, but it's definitely concerning.

I'm worried about driving it like this. Has anyone else experienced similar issues with their Hemi Challenger? Any ideas what might be causing this or what I should check first before taking it to a shop? Thanks for any help!

✓ Accepted solution

ClearTheCode Admin

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

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ClearTheCode admin answer:

It sounds like your 2018 Dodge Challenger R/T is experiencing a common issue related to engine misfires. The rough idle, loss of power, and check engine light are classic symptoms. Here's a breakdown of potential causes and steps:

Common Causes:

  1. Spark Plugs/Ignition Coils: Worn spark plugs or failing ignition coils are very common culprits for misfires. The Hemi engine can be particularly sensitive to these components.
  2. Fuel Injectors: A clogged or faulty fuel injector can cause a cylinder to run lean or rich, leading to misfires.
  3. PCV Valve: A stuck or clogged Positive Crankcase Ventilation (PCV) valve can affect engine vacuum and lead to rough idling.
  4. Oxygen Sensors: Faulty O2 sensors can send incorrect data to the engine control module (ECM), leading to improper fuel mixture and misfires.
  5. Valve Lifters (Hemi Tick): While often associated with a ticking noise, failing lifters can sometimes lead to misfires if they prevent proper valve operation. This is less common for just misfires but worth noting for Hemi engines.

Diagnostics & Next Steps:

  1. Retrieve OBD-II Codes: The first and most crucial step is to get the diagnostic trouble codes (DTCs) from your vehicle's OBD-II port. Common misfire codes include:
    • P0300: Random/Multiple Cylinder Misfire Detected
    • P0301 - P0308: Cylinder 1-8 Misfire Detected (e.g., P0302 indicates a misfire in cylinder 2)
  2. Inspect Spark Plugs and Coils: If a specific cylinder misfire code is present, inspect the spark plug and ignition coil for that cylinder. Look for signs of wear, oil fouling, or damage.
  3. Check Fuel System: Ensure adequate fuel pressure and consider testing fuel injectors if no ignition issues are found.
  4. Vacuum Leaks: Check for any visible vacuum leaks around the intake manifold or hoses.

When to See a Shop:

  • Immediately: If the check engine light is flashing, this indicates a severe misfire that could be damaging your catalytic converter. Drive as little as possible or have it towed.
  • Soon: If you've retrieved codes and performed basic visual checks but are unsure how to proceed, or if the problem persists after replacing simple components. A professional shop has specialized diagnostic tools to pinpoint the exact cause, especially for more complex issues like fuel system problems or internal engine components.
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