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Rough Idle and Occasional Stall on 2023 718 Cayman S

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Mike T. · rep 0 · May 25, 4:49 AM · 1 replies · solved · Question

Vehicle: 2023 Porsche 718 Cayman S

Hi everyone,

I'm having a concerning issue with my 2023 Porsche 718 Cayman S, which only has about 12,000 miles on it. For the past week or so, I've noticed a rough idle, especially when the engine is warm. It feels like the car is vibrating more than usual when stopped at a light or in traffic.

Even more concerning, the engine has occasionally stalled completely when coming to a stop or just after starting. It's not happening every time, but it's happened twice now, and it's quite unnerving for such a new car. There's no Check Engine Light on, which is puzzling.

Has anyone with a 718 Cayman S experienced a rough idle or stalling issues, especially without a CEL? I'm debating whether to take it to the dealer immediately. Any thoughts on what might be going on?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 4:49 AM

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ClearTheCode admin answer:

Experiencing a rough idle and occasional stalling on a relatively new 2023 Porsche 718 Cayman S with no Check Engine Light (CEL) is definitely concerning and warrants prompt attention. While the lack of a CEL can be puzzling, it doesn't mean there aren't underlying issues.

  1. Common Causes & Diagnostics:

    • Fuel System Issues:
      • Contaminated Fuel: Bad or contaminated fuel can cause rough running and stalling. Ensure you're using premium fuel from a reputable station.
      • Clogged Fuel Injectors: Even on a new car, a partially clogged injector can lead to an uneven air-fuel mixture in one or more cylinders, causing a rough idle. It might not be severe enough to trigger a misfire code (P030x) if it's intermittent.
      • Fuel Pump/Pressure: Issues with fuel pressure, either from the low-pressure or high-pressure fuel pump, can cause the engine to starve for fuel, leading to rough idle and stalling.
    • Ignition System: While less common on a new car, a faulty spark plug or ignition coil could cause intermittent misfires that are felt as a rough idle or even stalling, but not yet severe enough to trigger a CEL.
    • Vacuum Leaks: A small vacuum leak in the intake system can introduce unmetered air, disrupting the air-fuel mixture and causing a rough idle. These can be tricky to find.
    • Mass Airflow Sensor (MAF) or Oxygen Sensors: A slightly faulty MAF or O2 sensor could be sending inaccurate readings to the Engine Control Unit (ECU), leading to an incorrect air-fuel mixture, but not yet outside the parameters that would trigger a CEL.
    • Idle Air Control Valve (if applicable): While many modern cars use throttle body control for idle, if an IACV is present and sticking, it can cause idle issues.
    • Software Glitch/Adaptation: Sometimes, a software anomaly or an issue with the engine's adaptive learning can cause these symptoms.

  2. When to See a Shop:

    • Immediately: Given the car is stalling, this is a safety concern, especially in traffic. You should have it inspected by a Porsche dealership or a qualified Porsche specialist as soon as possible. Do not delay.
    • Professional Diagnosis: Even without a CEL, a professional scan tool can often reveal pending codes, freeze-frame data, or live data parameters that are out of specification, which can help diagnose the issue. The dealership will have the specific diagnostic software and tools to thoroughly test the fuel system, ignition, sensors, and check for any software updates or adaptations that might resolve the problem. They can also perform a smoke test for vacuum leaks.
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