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2018 Q50 Red Sport 400 Transmission Shudder and Hesitation

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Brian F. · rep 0 · May 22, 5:04 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 Red Sport 400

Hey everyone,

I'm experiencing a really frustrating issue with my 2018 Infiniti Q50 Red Sport 400. Lately, I've noticed a distinct shudder or hesitation, particularly when accelerating from a stop or at lower speeds, usually between 15-30 mph. It feels like the transmission is struggling to decide which gear to be in, or perhaps slipping.

It's not constant, but it's becoming more frequent, especially after the car has warmed up. Sometimes it feels like a slight jolt, other times it's more of a vibration through the drivetrain. I'm worried this could be a serious transmission problem.

Has anyone else with a 2018 Q50, especially the Red Sport 400, experienced anything similar? What was the diagnosis, and what was the fix? Any advice on what I should check or mention 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:

It sounds like you're describing a common concern with the 7-speed automatic transmission found in your 2018 Infiniti Q50 Red Sport 400. Transmission shudder or hesitation can stem from several sources, and it's important to get it diagnosed properly.

Here are some potential causes and steps:

  1. Transmission Fluid Condition:

    • Cause: Old, contaminated, or low transmission fluid can lead to poor lubrication and hydraulic pressure, causing shuddering or delayed shifts. Even if the fluid level appears correct, its quality can degrade over time.
    • Action: Check the transmission fluid level and condition. If it's dark, smells burnt, or is low, a fluid and filter change might be necessary. However, for some modern transmissions, a simple fluid change might not be the complete solution.

  2. Torque Converter Issues:

    • Cause: The torque converter is responsible for transferring power from the engine to the transmission. If it's failing, it can cause shuddering, especially during lock-up (when it creates a direct connection between the engine and transmission).
    • Action: This often requires professional diagnosis, as it's an internal transmission component.

  3. Transmission Control Module (TCM) Software:

    • Cause: Sometimes, the issue can be resolved with a software update for the Transmission Control Module. Manufacturers often release updates to refine shift logic, improve drivability, and address known issues.
    • Action: A dealership can check for and apply any available TCM software updates.

  4. Valve Body or Solenoid Problems:

    • Cause: The valve body directs hydraulic fluid to engage different gears, and solenoids control the fluid flow. A faulty valve body or sticking solenoid can lead to erratic shifting or shudder.
    • Action: This is an internal transmission repair that requires specialized tools and expertise.

Common OBD Codes (if present):

  • P0700: Transmission Control System Malfunction (a generic code indicating a transmission issue, often accompanied by more specific codes).
  • P073X: Incorrect Gear Ratio (e.g., P0731 for Gear 1, P0732 for Gear 2, etc., indicating a slip).
  • P0741: Torque Converter Clutch Circuit Performance or Stuck Off.

When to See a Shop: Given that your vehicle is a 2018 model and the issue involves the transmission, it's highly recommended to take your Infiniti Q50 to a qualified Infiniti dealership or a reputable transmission specialist as soon as possible. Continuing to drive with a shuddering transmission can potentially lead to more severe and costly damage. They have the specialized diagnostic tools to accurately pinpoint the root cause, whether it's a software glitch, fluid issue, or a mechanical component failure.

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