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Discussion Starter · #1 · (Edited)
I got a P0304 related to a fouled spark plug. Drove it to the dealership with no noticeable performance issues. It has not been using excessive oil.

Dealership is telling me to rebuild the engine ($4500) and while I am at it, might as well do the timing belt since the engine will be out. It is sitting at the dealership now.

I called Honda US -- and they said, tough luck. Out of warranty.

Is is really wise to rebuild the engine over one fouled plug? Is this just the dealer wanting $$$?

Rather than rebuild, would it make sense to replace the plug and put on something to turn off the variable cylinders? Might that solve the issue?

Is the 4th cylinder one of the variable ones?

A rebuild at 74K -- that sucks!

Thanks for any input.

Newbie to the board...
 

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Rebuild may be the solution if the service tech found the compression in that cylinder low compared to the other cylinders. Since you stated the engine runs fine continue running the vehicle as is could be a viable temporary solution. But the return of the PO304 or worse is likely to return.
 

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Do not rebuild the engine. You only need a rebuilt engine if your cylinder is scored(camera) or your having rod or main bearing issues. This is unlikely at 74k. You may just need a valve job.
Yes, #4 is a cylinder that is dormant during VCM operation. #4 will have more deposits on it becsuse of the VCM. It could be a valve sticking or not seating well because of the oil and carbon deposits.
Definitely get a VCM deactivation device.
Change spark plugs.
Buy fuel that is branded (Exxon, Shell, Chevron, Valero etc. 87 octane).
Use fuel injector cleaner for a few tanks.
Take your vehicle on long drives.
The idea is in hopes of the valve and cylinder will clean up and begin working better.
Check the new spark plug to see if things are any better. You might consider going to 0w30 oil cold or 5w30 if your in a warmer climate. This will help with compression and keep oil from burning in your cylinder. It offers better engine wear protection. You may give up a fraction of your fuel economy using a slightly heavier oil.
These are my thoughts. I have a V6 in a Crosstour with 230k miles and its still going. My #4 spark plug was always blackened. Just recently deactivated VCM.
Get a 2nd opinion from a skillful mechanic. Check this video out.

Watch "Honda Ridgeline Poor Running - Misfire Low Cylinder Contribution" on YouTube
 

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The dealership should give you the exact diagnostics they used to recommend a "rebuild", particularly the results of a compression test. If they didn't do the test or can't give you specifics, take your car elsewhere. If you want to throw parts at it hoping for a solution without doing diagnostic tests, then certainly replacing the offending spark plug is the place to start - that shouldn't run you more than $25 or so including labor. If it fouls again, then you know you have a problem in that cylinder which could be the injector, valves, rings, etc. There are additional tests you can run to isolate the likely cause.

But the key is to get it to someone who will run proper tests and determine exactly what the problem is.

If the engine does have major internal issues, usually the most cost effective approach is to replace it with a used engine. I would never allow a dealership to do a major engine rebuild as this is not their speciality and few have the expertise, especially with respect to the the machining work.

As an aside, I have no idea how you would "rebuild" an engine and not replace the timing belt. All this makes me very skeptical the dealership is dealing with you in a straightforward way. This has the smell of them seeing someone they can take advantage of with a blank check to do $4500 of work when a relatively simple fix may be possible.

- Mark
 

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Discussion Starter · #5 ·
First -- thanks for the great info. It helped me to ask more questions of the dealership. I really appreciate it. I watch much of the video attached...clearly this work is beyond my pay grade!

The service guy said that they did check the compression and fuel injectors. He said the problem I am having is just like the issues that were involved in the 2013 versions that received relief from Honda -- and they had plenty of those. This is only the second 2015 where he has seen the problem. They will not have to do any machining, but will fix the rings that are the problem. He said that they have tried a variety of short term fixes and software upgrades in a 2014 that came in on trade. They used it for a test car in the loaner fleet while they tried other options. He said that if they do what they quote, I will not see this problem again. He did not consider a used engine...so I would need to go to an independent garage for that.

He said that neutralizing the VCM would not help any thing since the cylinder is bad.

I will call a large, independent garage that specializes in Hondas only on Monday to get their opinion and quote.
 

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First -- thanks for the great info. It helped me to ask more questions of the dealership. I really appreciate it. I watch much of the video attached...clearly this work is beyond my pay grade!

The service guy said that they did check the compression and fuel injectors. He said the problem I am having is just like the issues that were involved in the 2013 versions that received relief from Honda -- and they had plenty of those. This is only the second 2015 where he has seen the problem. They will not have to do any machining, but will fix the rings that are the problem. He said that they have tried a variety of short term fixes and software upgrades in a 2014 that came in on trade. They used it for a test car in the loaner fleet while they tried other options. He said that if they do what they quote, I will not see this problem again. He did not consider a used engine...so I would need to go to an independent garage for that.

He said that neutralizing the VCM would not help any thing since the cylinder is bad.

I will call a large, independent garage that specializes in Hondas only on Monday to get their opinion and quote.
I'm not saying he's right or wrong that the cylinder is bad. If bad means it's lost compression. I'd want to know if the cylinder is scored. If it's not, then there is no need to re-ring the piston in the problem cylinder. A camera dropped through the spark plug hole can see this. Otherwise, like in the video (part 1), it's likely a burnt/chipped/caked valve. The cylinder was not damaged (scored) in the video (part 2). A head/valve job is a less expensive fix.

Disable the VCM as soon as possible. True, it won't fix a damaged cylinder wall or a bad valve, but it could help clean up the cylinder if its firing 100% of the time. The VCM is what likely caused your problem in the first place.

YES, get outside help. The service manager is doubling down.
 

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Not a chance I would fool with a used engine. I don't think you'd save all that much and who knows the condition of it when it was yerked out. Yes, 5k is substantial-but not really in relation to the price of new vehicles IMO.
 

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I would go with crate engine was done in the US not japan ..tokyo or china ..or where ever these stupid things claim they come from.
 

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DO NOT get an engine rebuilt. Find a Honda/Acura specialist in your area and tell them the situation. Usually those guys won't even charge for a "diagnostic" but even if they do, it's cheaper than a rebuild. This seems sketchy to me and I would find it extremely hard to believe that a 5 year old Pilot would need a rebuild. Hope you can figure out what's wrong and that its a cheap and relatively easy fix!
 

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I got a P0304 related to a fouled spark plug. Drove it to the dealership with no noticeable performance issues. It has not been using excessive oil.

Dealership is telling me to rebuild the engine ($4500) and while I am at it, might as well do the timing belt since the engine will be out. It is sitting at the dealership now.

I called Honda US -- and they said, tough luck. Out of warranty.

Is is really wise to rebuild the engine over one fouled plug? Is this just the dealer wanting $$$?

Rather than rebuild, would it make sense to replace the plug and put on something to turn off the variable cylinders? Might that solve the issue?

Is the 4th cylinder one of the variable ones?

A rebuild at 74K -- that sucks!

Thanks for any input.

Newbie to the board...
You might try replacing the plugs, deactivating the VCM and seeing how long you go before you get a "check engine" and associated idiot lights related to oil fouling. You may be surprised that the rings are sufficient to prevent additional fouling if the VCM is deactivated. And sometimes the fouling can be quite minor and still trigger the lights. On my wife's Pilot, the amount of oil fouling on the plugs was really minuscule according to the tech (the car never used any oil as indicated on the dipstick), but given the warranty program Honda paid for a re-ring. So there was no downside to it really. But if I were paying for it and it was very minor fouling, I would be inclined to take a chance on fresh plugs and muzzling VCM. There is nothing to lose in this approach.

Good luck.
 
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