Oil fouled spark plug

RPMCGARVEY1

MEMBER
2008 HONDA PILOT
3.5L
6 CYL
2WD
AUTOMATIC
165,000 MILES

Changing the spark plugs in my used vehicle listed above. Found cylinder number one (back passenger side of the engine block) had an oil-fouled spark plug (see added image). What is causing this?

I read via the below link.

"What causes oil fouled spark plugs?

Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly."

https://www.ngksparkplugs.ca › tech-info-spark-plug-faq

Is this the issue?

Can the Lucas Lucas Oil Products Heavy Duty Oil Stabilizer (1 qt.) correct this issue without tearing the engine apart?

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2 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Correct. More than likely this is a valve seal or piston ring. Basically you have oil in the cylinder that should not be there. Oil control rings on the piston are supposed to keep the oil from coming up from the crank case. The valve stem seals are supposed to keep the oil from coming in from the head. When they leak, you get the plug fouled. I would suggest changing the plug and checking it once every 100 miles for the next 500 miles and if it is okay then you can keep an eye on it. Basically you just want to make sure this is not a misfire that just accumulated fuel and soot due to a faulty plug. If there is an oil leak then it will happen again and then we can take the next step.

The indicator we need to look for is smoke. If you see it at start up then that is most likely valve seals. If you see it on decel then that is most likely piston rings.

Let me know what you find. Thanks

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Monday, November 18th, 2019 AT 5:12 PM

RPMCGARVEY1

MEMBER
3 POSTS

Thank you for your reply. However, after completing further research this is a common issue with any Honda "models equipped with the 3.5-liter V6 with Variable Cylinder Management (VCM), which might [cause] engine misfire, excessive oil burning, and premature spark plug fouling issues". Honda Pilots (2009-13) were supplied with an extended warranty from Honda under a class action lawsuit (https://www.autoblog.com/2013/10/23/honda-settles-class-action-lawsuit-engines/); however, any Honda with Variable Cylinder Management (VCM) might experience engine misfire, excessive oil burning, and premature spark plug fouling issues. Variable Cylinder Management (VCM) basically shuts down/disables cylinders during idle or cruising conditions in order to save fuel and emissions, however by doing this, my understanding is this creates a vacuum in the disable cylinders which pulls lubrication away causing engine misfire, excessive oil burning, and premature spark plug fouling issues. Through my research, I have found a relatively simple and inexpensive correct call a VCMTuner (https://www.vcmtuner.com/) which essentially disables the VCM. My plan now is to install this VCMTuner, replace the fouled spark plug, clean/replace the PVC Valve and change the oil. I believe this will correct entirely or reduce this oil-fouled spark/starting issue.

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Friday, January 17th, 2020 AT 5:08 AM