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2017 Pilot Oil Consumption & Misfire - VCM Related?

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Chris P. · rep 0 · May 25, 1:51 AM · 1 replies · solved · Question

Vehicle: 2017 Honda Pilot Touring

I own a 2017 Honda Pilot Touring with about 85,000 miles. Lately, I've noticed it's consuming an unusual amount of oil between changes, and I recently got a check engine light with a P030X code (cylinder misfire, specifically P0301). The car also feels a bit rough at idle sometimes.

I've heard about Honda's Variable Cylinder Management (VCM) system causing issues like excessive oil consumption and misfires in these engines. Could this be related to VCM? What are my options, and what's the typical repair for this if it is VCM related?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:51 AM

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ClearTheCode admin answer:

Your suspicion regarding the Variable Cylinder Management (VCM) system in your 2017 Honda Pilot is well-founded. The symptoms you describe – excessive oil consumption, P030X misfire codes (P0301 indicates a misfire in cylinder 1), and rough idle – are classic indicators of VCM-related issues in Honda's J-series V6 engines.

How VCM Causes Problems: VCM deactivates cylinders (typically 3 of the 6) during light-load cruising to improve fuel economy. However, this can lead to:

  1. Oil Consumption: The piston rings in the deactivated cylinders can become fouled with carbon deposits, preventing them from sealing properly. This allows oil to bypass the rings and burn off in the combustion chamber.
  2. Spark Plug Fouling: Excessive oil burning leads to fouled spark plugs in the affected cylinders, causing misfires (P0301, P0302, P0303, P0304, P0305, P0306 depending on which cylinder is misfiring).
  3. Engine Vibration: The transition between 3-cylinder and 6-cylinder mode can cause noticeable vibrations and roughness.

Recommended Actions:

  1. Diagnosis: Confirm the misfire and oil consumption are VCM-related. A mechanic can perform a cylinder compression test and a leak-down test, especially on the misfiring cylinder, to check for ring issues. They can also inspect spark plugs for oil fouling.
  2. Spark Plug Replacement: If the plugs are fouled, replacing them is a temporary fix for the misfire. However, without addressing the root cause, they will likely foul again.
  3. VCM Deactivation Device (Muzzler): Many owners choose to install an aftermarket VCM deactivation device (often called a 'VCM muzzler' or 'VCM disabler'). These devices trick the engine's computer into thinking the engine is always under load, preventing VCM from engaging. This can significantly reduce oil consumption and prevent future misfires by keeping all cylinders active and hot.
  4. Piston Ring Replacement (Major Repair): For severe cases of oil consumption where VCM deactivation hasn't helped, or if compression tests show significant ring wear, the ultimate solution is often replacing the piston rings on the affected cylinders. This is a costly and labor-intensive engine overhaul.

When to see a shop:

  • Immediately for the P0301 code, as prolonged misfires can damage the catalytic converter.
  • To accurately diagnose the extent of oil consumption and the condition of the piston rings.
  • If you decide to install a VCM deactivation device and are not comfortable doing it yourself.
  • If a major repair like piston ring replacement is indicated.
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