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2018 Q50 Red Sport 400 - Whistling Noise and Reduced Power (P0299)

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

Vehicle: 2018 Infiniti Q50 Red Sport 400

Hey everyone,

I've got a 2018 Infiniti Q50 Red Sport 400 with about 65,000 miles on it. Recently, I've noticed a distinct whistling sound coming from the engine bay, especially when accelerating. Along with this, the car feels like it's lost a good chunk of its power, almost like the turbos aren't kicking in properly.

The check engine light came on, and when I scanned it, I got a P0299 code, which points to an 'Engine Underboost' condition. I'm worried it might be something serious with the turbos or related components.

Has anyone else experienced this with their VR30DDTT engine? What was the cause, and what kind of repair costs should I expect? Any advice on troubleshooting before I take it to the dealership would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

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

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ClearTheCode admin answer:

The P0299 code (Engine Underboost) on your 2018 Infiniti Q50 Red Sport 400, especially with a whistling noise and reduced power, strongly suggests an issue within the turbocharger system or its associated plumbing. The VR30DDTT engine is known for its performance, but like any forced induction system, it can develop issues.

Here are the common causes and steps:

  1. Boost Leak: This is the most frequent cause. Check all intercooler pipes, charge pipes, and vacuum lines for cracks, loose connections, or damaged O-rings. A whistling sound often indicates air escaping under pressure.
  2. Turbocharger Wastegate Actuator Issues: The wastegate controls boost pressure. If an actuator is failing or stuck open, it can lead to underboost. Sometimes the linkage can become loose or corroded.
  3. Turbocharger Failure: While less common on a 2018 model unless heavily modified or poorly maintained, a failing turbo bearing can cause a whistling sound and lead to underboost. Look for excessive shaft play or oil leaks around the turbo.
  4. Diverter Valve/Bypass Valve Failure: These valves release excess boost pressure. If one is stuck open or leaking, it will prevent the engine from building full boost.
  5. MAP/MAF Sensor Issues: A faulty Manifold Absolute Pressure (MAP) sensor or Mass Air Flow (MAF) sensor could be providing incorrect readings, causing the ECU to limit boost. However, a P0299 usually points more directly to a physical boost issue.

When to see a shop: Given the reduced power and the P0299 code, it's advisable to have a qualified technician diagnose this promptly. Continuing to drive with an underboost condition can strain other engine components or lead to further damage if the turbocharger itself is failing. A shop can perform a smoke test to pinpoint boost leaks and properly diagnose turbocharger health.

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