The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2018 Q50 3.0t Rough Idle & CEL - Misfire?

0

Chris P. · rep 0 · May 22, 5:09 AM · 1 replies · solved · Question

Vehicle: 2018 Infiniti Q50 3.0t Red Sport

Hey everyone,

My 2018 Infiniti Q50 3.0t Red Sport (around 75,000 miles) has developed a really rough idle lately. It feels like it's shaking more than usual when I'm stopped at a light.

The Check Engine Light also came on a couple of days ago. I haven't noticed any major power loss, but there's definitely a slight hesitation sometimes when accelerating from a stop.

Could this be a misfire? What are the common culprits for the VR30DDTT engine at this mileage? I'm hoping it's something I can tackle myself or at least diagnose before heading to the dealership. Any advice on where to start looking would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:09 AM

0

ClearTheCode admin answer:

It sounds like your 2018 Infiniti Q50 3.0t Red Sport is experiencing symptoms consistent with an engine misfire or a related issue. Given your mileage of 75,000, this is a common point where certain maintenance items might need attention.

Here's a breakdown of potential causes and diagnostic steps:

  1. Check for OBD-II Codes: The first and most crucial step is to get the Check Engine Light (CEL) codes read. You can do this with an OBD-II scanner, often available for free use at auto parts stores. Common codes for misfires include P030X (where X is the cylinder number, e.g., P0301 for cylinder 1 misfire) or P0300 for a random/multiple misfire.

  2. Common Causes for VR30DDTT Rough Idle/Misfire:

    • Spark Plugs: At 75,000 miles, your spark plugs are likely due for replacement if they haven't been changed already. Worn plugs are a very common cause of misfires and rough idle. The VR30DDTT engine uses iridium-tipped plugs, which have a longer life but still degrade.
    • Ignition Coils: A failing ignition coil on one or more cylinders can lead to misfires. If you get a specific P030X code, swapping that coil with another cylinder's coil can help diagnose if the coil is the issue.
    • Fuel Injectors: Clogged or faulty fuel injectors can cause a cylinder to run lean or rich, leading to misfires. Fuel system cleaners can sometimes help, but a faulty injector may need replacement.
    • Air Filter/MAF Sensor: A very dirty air filter can restrict airflow, and a contaminated Mass Air Flow (MAF) sensor can send incorrect readings to the ECU, affecting fuel-air mixture and causing rough idle. Check and clean/replace as needed.
    • Vacuum Leaks: Less common but possible, a vacuum leak can introduce unmetered air into the engine, leading to a lean condition and rough idle.

  3. When to See a Shop:

    • If the CEL is flashing, this indicates a severe misfire that could damage the catalytic converter. Drive as little as possible and get it to a shop immediately.
    • If you've read the codes and performed basic checks (like inspecting spark plugs or air filter) but the issue persists, or if you're uncomfortable performing these diagnostics yourself, it's best to consult a qualified Infiniti mechanic. They have specialized diagnostic tools to pinpoint the exact cause, especially for more complex issues like fuel injector problems or internal engine concerns.

Starting with the OBD-II codes will give you the best direction for troubleshooting. Good luck!

Menu

Help & account