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2018 Q50 3.0t Rough Idle & Misfire - Losing Power

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David L. · rep 0 · May 22, 5:04 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 3.0t Red Sport

Hey everyone,

I'm having some serious issues with my 2018 Infiniti Q50 3.0t Red Sport. Lately, it's been idling really rough, especially when I'm stopped at a light. It feels like the engine is shaking more than usual.

The biggest problem is the loss of power. When I try to accelerate, it feels sluggish and sometimes even stutters, like it's struggling to get going. The check engine light came on a few days ago, and I'm worried about what might be going on.

I haven't noticed any strange noises, but the exhaust does smell a bit off, almost like it's running rich. Has anyone else experienced this with their VR30 engine? Any ideas on what I should check first before taking it to the dealer? Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:04 AM

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ClearTheCode admin answer:

It sounds like your 2018 Infiniti Q50 3.0t Red Sport is experiencing classic symptoms of an engine misfire, which can lead to rough idling, reduced power, and an illuminated Check Engine Light (CEL). The 'off' exhaust smell could indicate unburnt fuel passing through the exhaust system due to incomplete combustion.

Common Causes & Diagnostics:

  1. Spark Plugs: Worn or fouled spark plugs are a very common cause of misfires. The VR30DDTT engine, especially in higher mileage or tuned applications, can be sensitive to spark plug condition.
  2. Ignition Coils: A failing ignition coil for one or more cylinders can prevent proper spark delivery, leading to a misfire.
  3. Fuel Injectors: Clogged or faulty fuel injectors can cause an improper fuel-air mixture, resulting in misfires.
  4. Vacuum Leaks: Leaks in the intake system can introduce unmetered air, disrupting the fuel-air ratio and causing rough running.
  5. Turbocharger Issues: While less common for just misfires, issues with the twin turbos (e.g., wastegate problems, boost leaks) can contribute to power loss and sometimes trigger misfire codes if the engine management system detects abnormal combustion.

Recommended Steps:

  1. Retrieve OBD-II Codes: The first and most crucial step is to get the diagnostic trouble codes (DTCs) read. A common code for misfires is P030x, where 'x' indicates the cylinder number (e.g., P0301 for cylinder 1, P0300 for random/multiple misfires). Other relevant codes might include P0171/P0174 (lean condition) or P0172/P0175 (rich condition).
  2. Inspect Spark Plugs & Coils: Once you have the misfire code, you can focus on the specific cylinder(s). Inspect the spark plug for wear, fouling, or damage. You can also swap the ignition coil from the misfiring cylinder to a known good one to see if the misfire follows the coil.
  3. Check for Vacuum Leaks: Visually inspect all vacuum lines and intake connections for cracks or disconnections.
  4. Fuel System Check: If spark and air seem fine, a fuel pressure test or injector flow test might be necessary.

When to See a Shop:

If you've retrieved the codes and performed basic visual inspections without identifying the clear cause, or if you're uncomfortable performing these checks yourself, it's highly recommended to take your Infiniti to a qualified mechanic or dealership. Driving with a persistent misfire can lead to further damage, particularly to the catalytic converters, which can be very expensive to replace. A professional can perform more in-depth diagnostics, including compression tests, leak-down tests, and advanced sensor readings, to pinpoint the exact issue.

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