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2018 Charger R/T intermittent misfire and P030X codes

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Chris P. · rep 0 · May 24, 3:15 PM · 1 replies · solved · Question

Vehicle: 2018 Dodge Charger R/T

Hey everyone, I'm hoping someone can help me out with an issue I'm having with my 2018 Dodge Charger R/T. Lately, it's been running a bit rough, especially at idle, and I've noticed some hesitation when accelerating.

The check engine light came on, and when I scanned it, I got a few codes: P0301, P0303, and sometimes P0300. It seems to be primarily cylinders 1 and 3 that are misfiring, but the random misfire code (P0300) also pops up.

The problem is intermittent; some days it runs fine, and others it's really noticeable. I've heard about spark plug issues or coil packs being common on these Hemi engines. Any thoughts on what I should check first before taking it to a mechanic?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 3:15 PM

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ClearTheCode admin answer:

Intermittent misfires on your 2018 Dodge Charger R/T, especially with P0301, P0303, and P0300 codes, indicate a problem with the combustion process in specific cylinders and potentially across multiple cylinders. Here's a breakdown of common causes and diagnostic steps:

  1. Spark Plugs and Ignition Coils:

    • Cause: Worn spark plugs, fouled plugs, or failing ignition coils are very common culprits for misfires. A weak spark can lead to incomplete combustion.
    • Action: Given the specific cylinder codes (P0301, P0303), start by inspecting and potentially swapping the spark plugs and ignition coils for cylinders 1 and 3 with known good ones from other cylinders (e.g., 2 and 4). If the misfire code follows the coil or plug, you've found your issue.

  2. Fuel Delivery Issues:

    • Cause: Clogged fuel injectors for cylinders 1 and 3, low fuel pressure, or contaminated fuel can starve the cylinder of necessary fuel.
    • Action: Check fuel pressure with a gauge. Consider having the fuel injectors tested or cleaned. You can also try adding a high-quality fuel system cleaner to your tank.

  3. Vacuum Leaks:

    • Cause: Unmetered air entering the engine can lean out the air/fuel mixture, leading to misfires, especially at idle.
    • Action: Visually inspect all vacuum hoses and intake manifold gaskets for cracks or leaks. A smoke test can effectively pinpoint hard-to-find leaks.

  4. Engine Compression:

    • Cause: Low compression in a cylinder due to worn piston rings, burnt valves, or a blown head gasket will prevent proper combustion.
    • Action: A compression test is crucial if other diagnostics don't reveal the problem. This will tell you if the cylinder itself has an internal issue.

When to See a Shop: If you've checked the spark plugs, coils, and visually inspected for vacuum leaks without success, it's best to take your Charger to a qualified mechanic. Diagnosing fuel injector issues, performing compression tests, or smoke tests often requires specialized tools and expertise. Continuing to drive with a persistent misfire can lead to further damage, including catalytic converter failure.

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