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2017 Mini Cooper JCW - Engine Misfire and Rough Idle, CEL Flashing

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Mike T. · rep 0 · May 25, 4:56 AM · 1 replies · solved · Question

Vehicle: 2017 Mini Cooper John Cooper Works (F56)

Hi Mini community,

I'm having a serious problem with my 2017 Mini Cooper JCW. The engine has developed a really rough idle, and it feels like it's misfiring, especially when I'm stopped at a light. The Check Engine Light started flashing, which I know means a severe misfire. It's also lost some power and feels sluggish under acceleration.

I've checked the oil, and it seems fine. I'm worried about driving it like this. What could be causing a flashing CEL and misfires on a JCW? It has about 55,000 miles on it. Any advice on what to look for or what might be the common culprits?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:56 AM

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ClearTheCode admin answer:

A flashing Check Engine Light (CEL) indicates a severe misfire that could potentially damage your catalytic converter due to unburnt fuel entering the exhaust system. It's crucial to address this immediately.

Common Causes for Misfires in Mini JCW (B48/B58 Engines):

  • Ignition System Failure:
    • Spark Plugs: Worn, fouled, or incorrectly gapped spark plugs are a very common cause of misfires.
    • Ignition Coils: A failing ignition coil pack on one or more cylinders can prevent proper spark.
  • Fuel System Issues:
    • Fuel Injectors: Clogged or failing fuel injectors can deliver too little or too much fuel, leading to misfires.
    • High-Pressure Fuel Pump (HPFP): A failing HPFP can cause insufficient fuel pressure, leading to lean misfires.
    • Low-Pressure Fuel Pump (LPFP): Issues with the in-tank fuel pump can also affect fuel delivery.
  • Engine Mechanical Issues: (Less common but serious)
    • Low Compression: Worn piston rings, valves, or a blown head gasket can cause a loss of compression in a cylinder.
    • Valve Train Problems: Issues with variable valve timing (VANOS) or valve lift (Valvetronic) components.
  • Sensor Malfunctions: Faulty oxygen sensors, mass airflow sensor, or crankshaft/camshaft position sensors can send incorrect data, leading to misfires.

What You Can Do (Initial Checks):

  1. Stop Driving Immediately: If the CEL is flashing, minimize driving to prevent catalytic converter damage. If you must drive, do so gently and for the shortest distance possible.
  2. Retrieve OBD-II Codes: The most important first step. Use an OBD-II scanner to read the diagnostic trouble codes (DTCs). You'll likely see codes like P0301, P0302, P0303, P0304 (Misfire Detected in Cylinder 1, 2, 3, or 4 respectively) or P0300 (Random/Multiple Cylinder Misfire Detected). These codes will point you to the specific cylinder(s) affected.

When to See a Shop:

  • Urgent Care: Due to the flashing CEL, you should get your Mini to a qualified technician as soon as possible. Driving with a severe misfire can lead to very expensive repairs.
  • Professional Diagnosis: A Mini or BMW specialist will have advanced diagnostic tools to pinpoint the exact cause of the misfire. They can perform cylinder contribution tests, fuel pressure tests, compression tests, and oscilloscope tests on ignition components to accurately diagnose the problem.
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