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2020 MDX V6 - Excessive Oil Consumption and Rough Idle

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Mike T. · rep 0 · May 25, 3:40 AM · 1 replies · solved · Question

Vehicle: 2020 Acura MDX Technology Package

Hi everyone,

I own a 2020 Acura MDX with the 3.5L V6 engine, currently at about 45,000 miles. Over the past few months, I've noticed that I'm adding oil much more frequently than I should be. I'm talking about a quart every 1,500-2,000 miles, which seems excessive for a relatively new car. I don't see any obvious leaks under the car.

Lately, I've also started experiencing a slightly rough idle, especially when the engine is warm. It's not a violent shake, but definitely noticeable. Could these two issues be related? I'm worried about the long-term health of the engine. Is this a known issue with the MDX V6 engines and their Variable Cylinder Management (VCM) system?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:40 AM

0

ClearTheCode admin answer:

Excessive oil consumption combined with a rough idle on a 2020 Acura MDX 3.5L V6 is a concerning issue, and it can indeed be related to the Variable Cylinder Management (VCM) system.

Understanding VCM and Oil Consumption:

Acura's VCM system deactivates cylinders (typically 3 of 6) under light load conditions to improve fuel economy. While generally effective, it has been linked to issues in some Honda/Acura V6 engines, including:

  1. Piston Ring Issues: The piston rings on the deactivated cylinders can sometimes stick or become fouled due to inconsistent lubrication and combustion, leading to oil bypassing the rings and being burned.
  2. Spark Plug Fouling: Burning oil can foul spark plugs, especially in the cylinders most affected by VCM, leading to misfires and a rough idle. If severe, this could trigger P030x (misfire) codes.
  3. Carbon Buildup: Increased oil consumption can contribute to carbon buildup on intake valves and piston crowns, further exacerbating misfires and potentially affecting engine performance.

Recommended Steps:

  1. Document Oil Consumption: Start meticulously tracking your oil consumption. Note mileage, date, and amount of oil added. This data is crucial for dealership warranty claims.
  2. Check for DTCs: Even without a Check Engine Light, a pending P030x (misfire) code might be present. Have a scan tool check for any stored or pending diagnostic trouble codes.
  3. Spark Plug Inspection: If you're comfortable, inspect the spark plugs, particularly in the rear bank (cylinders 1-3-4, which are often deactivated). Fouled plugs are a strong indicator of oil burning.
  4. VCM Disabler (Temporary Consideration): Some owners opt for VCM disabler devices. While these can mitigate VCM-related issues, they are aftermarket and might void powertrain warranty if installed. Consult with your dealer first.

When to See a Shop:

  • Immediately, if the oil consumption is rapidly increasing or if the rough idle becomes more pronounced.
  • If a Check Engine Light illuminates with misfire codes (P0301, P0302, etc.) or catalyst efficiency codes (P0420, P0430) as a result of oil burning.
  • An Acura dealership can perform an oil consumption test and check for any technical service bulletins (TSBs) related to VCM or oil consumption for your specific model year. They may recommend engine deep cleaning, piston ring replacement, or other warranty-covered repairs depending on their diagnostic findings.
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