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Yesterday, our 2016 Odyssey Touring Elite CIL came on just shy of 45k miles. I read the one code it had out as P0303. My understanding is that that's a bad 3rd spark plug. I understand that earlier models had issues with oil getting past the piston ring and fouling up spark plugs earlier, and that the VCM also contributes to spark plugs fouling up early. When I called my dealership this morning to inquire about this, the mechanic mentioned that the class-action lawsuit settlement was for earlier models, and that the piston ring issue was not applicable to the 2016. The mechanic mentioned that it was unusual for a spark plug to fail this early. I drive this car very gently and economically, so I wonder if my driving, often time in ECO, has contributed to the plug failing earlier due to the VCM shutting it off.

The mechanic mentioned to just replace the 3rd spark plug instead of doing them all. He jokingly said I "ought to just gun it once in a while" instead of driving as economically as I do. My understanding is that this the spark plug closest to the driver (windshield driver side). Is that correct? I can't seem to find an accurate picture online.

If any of this information is incorrect, please set me straight. I'm here to learn. And, thank you! =)

Simon
 

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Well - first, P0303 is a misfire on cylinder 3 - it can be due to either the spark plug, the coil, or the injector - diagnosis usually involves moving parts around - swap the coils between two cylinders - if the misfire stays on 3, it's not the coil, then swap the plugs - if it follows the plug (or the plug from 3 looks like it's messed up when you remove it) then that's the issue - if the plug looks really oil fouled, then it could be rings. 45k miles is pretty early to have an issue with the type of plugs in your van (NGK iridium) - but it's certainly possible - particularly if someone tried to gap them before the sale and damaged the center conductor (the iridium is a small piece on the end of the electrode, and can be damaged easily with a gapping tool)
 

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Yesterday, our 2016 Odyssey Touring Elite CIL came on just shy of 45k miles. I read the one code it had out as P0303. My understanding is that that's a bad 3rd spark plug. I understand that earlier models had issues with oil getting past the piston ring and fouling up spark plugs earlier, and that the VCM also contributes to spark plugs fouling up early. When I called my dealership this morning to inquire about this, the mechanic mentioned that the class-action lawsuit settlement was for earlier models, and that the piston ring issue was not applicable to the 2016. The mechanic mentioned that it was unusual for a spark plug to fail this early. I drive this car very gently and economically, so I wonder if my driving, often time in ECO, has contributed to the plug failing earlier due to the VCM shutting it off.

The mechanic mentioned to just replace the 3rd spark plug instead of doing them all. He jokingly said I "ought to just gun it once in a while" instead of driving as economically as I do. My understanding is that this the spark plug closest to the driver (windshield driver side). Is that correct? I can't seem to find an accurate picture online.

If any of this information is incorrect, please set me straight. I'm here to learn. And, thank you! =)

Simon
welcome to the forum and welcome to VCM woes.

Muzzle the VCM...

do an advanced search for your code on this forum and also search VCM Muzzle.

lots of info on the subject.
 

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Discussion Starter #4
Thanks for the feedback, DrD, and the clarification on the code. That's a good idea to just swap the coils first. After clearing the engine code, how long might you expect it would take to see the engine code come up again? Also, is it generally fine to drive on this for a while (for diagnostic's sake)?
 

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Discussion Starter #5
welcome to the forum and welcome to VCM woes.

Muzzle the VCM...

do an advanced search for your code on this forum and also search VCM Muzzle.

lots of info on the subject.
Thanks for the advice! I searched and found links like P0303 Cylinder 3 Misfire Reports. There's advice in there to just take it to the dealership to look at and see if Honda will take care of it. Is that applicable even for these model years?

With respect to disabling the VCM, I'll do some more searching, but I see the VCMTuner II, for instance. Are there any preferred devices that work better than others?

Thank you!
 

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Welcome and Welcome to the VCM Woes Honda has delivered onto your doorstep...

Tuner II and the S-VCM are the two that most of us run. I have a '16 EXL now with about 55k on the clock, we Muzzled with an S-VCM at 41k.

Muzzling the VCM isn't likely to be popular with your Dealership (Stealership!), they'd rather have you come in and pay for costly repairs after all. So I wouldn't bring this up with them. But if under warranty they should own this issue, get it looked at and documented and in the meantime order a Muzzle. VERY easy to install, nothing too it. Our gas mileage on mid to long hauls has actually gone up with our S-VCM, the car drives on all six cylinders, all the time! I know, crazy concept, right? More responsive, no ECO Mode/VCM kick in and out, no unnecessary wear on your engine mounts, etc.

Also note, if you haven't done so, time to change your transmission fluid! Lots of write-ups here on that as well. The transmissions are weak on these things, but you can mitigate by updating the fluid often and if in hot weather/high load/towing you might want to consider a transmission cooler as well. Normal driving, probably not necessary; unless your in TX/AZ/FL/AL/etc.

Good luck!
 

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Discussion Starter #7
Welcome and Welcome to the VCM Woes Honda has delivered onto your doorstep...

Tuner II and the S-VCM are the two that most of us run. I have a '16 EXL now with about 55k on the clock, we Muzzled with an S-VCM at 41k.

Muzzling the VCM isn't likely to be popular with your Dealership (Stealership!), they'd rather have you come in and pay for costly repairs after all. So I wouldn't bring this up with them. But if under warranty they should own this issue, get it looked at and documented and in the meantime order a Muzzle. VERY easy to install, nothing too it. Our gas mileage on mid to long hauls has actually gone up with our S-VCM, the car drives on all six cylinders, all the time! I know, crazy concept, right? More responsive, no ECO Mode/VCM kick in and out, no unnecessary wear on your engine mounts, etc.

Also note, if you haven't done so, time to change your transmission fluid! Lots of write-ups here on that as well. The transmissions are weak on these things, but you can mitigate by updating the fluid often and if in hot weather/high load/towing you might want to consider a transmission cooler as well. Normal driving, probably not necessary; unless your in TX/AZ/FL/AL/etc.

Good luck!
Thank you very much, Andrew! Looks like I'll be resolving the current issue and ordering a muzzler then. I'm surprised to hear that mpg went up a bit. We had the transmission fluid replaced on a regular interval early on. I was a bit shocked to see just how early on the first replacement was. Perhaps that was just to clear our any metallic debris from initial use that the transmission sheds? We live in MD and haven't towed anything with it.
 

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VCMuzzler II is a VCM suppressor that works 90% of the time and takes minutes to install.

VCMTuner II is considered the best around here and disables the VCM totally, with the option to run wiring to the interior and install a dash switch to turn it on and off.
The install is a bit more involved over the VCMuzzler.

more info on both here...

Based on the experienced input from many members on this forum, and If it was my van experiencing this issue, I would do the following.
  • install either of the above muzzler.
  • change all the plugs
  • add a bottle of Chevron Techron concentrate to a full fuel tank.
Do 2 or 3 applications. one bottle per tankful of gas.
It wouldn't hurt to run a few more tanks of Chevron gas with Techron, after the concentrate treatments.

Also, from now on stick to only using top-tier gas in your vehicle.
 

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Discussion Starter #9
VCMuzzler II is a VCM suppressor that works 90% of the time and takes minutes to install.

VCMTuner II is considered the best around here and disables the VCM totally, with the option to run wiring to the interior and install a dash switch to turn it on and off.
The install is a bit more involved over the VCMuzzler.

more info on both here...

Based on the experienced input from many members on this forum, and If it was my van experiencing this issue, I would do the following.
  • install either of the above muzzler.
  • change all the plugs
  • add a bottle of Chevron Techron concentrate to a full fuel tank.
Do 2 or 3 applications. one bottle per tankful of gas.
It wouldn't hurt to run a few more tanks of Chevron gas with Techron, after the concentrate treatments.

Also, from now on stick to only using top-tier gas in your vehicle.
Thanks a lot for the advice! I ended up ordering a VCMTUNER II, six replacement NGK plugs, and two bottles of Techron. I should be able to get into it this weekend and get it done. Will update when I know more. I appreciate you all.
 

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good stuff, hopefully you got your plugs off of rockauto and not amazon.
lots of fake plugs and bad sellers there.

the back plugs, a magnetic spark plug socket and two shorter extensions make the job a lot easier.
I think I used a 6" and 3" extensions or , or maybe two 6" ones cant recall.

mostly a job by feel, but have one of those dollar store rectangle locker mirrors to help see in the back if needed.

also be careful not to lose those acorn nuts that hold the coil in place, a neodymium magnet is your friend.

Takes note of each plug location, and post pics of the plugs.
lots of insight into the condition of your cylinders, by how the plugs look.
#1 is the back left.

Torque specs
158928
 

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good stuff, hopefully you got your plugs off of rockauto and not amazon.
Can't stress this enough. Dealer, local auto parts store or reputable online retailer (RockAuto). If the spark plugs come from Amazon or eBay, you can assume they are fakes and will fail very quickly.

-Charlie
 

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Discussion Starter #12
Thanks a lot! Yeah, the back ones look a little trickier. It was so nice working on our old Civic and CR-V - all four plugs presented beautifully right up front in the I4 engines. I have several magnetic swivel spark plug sockets and extensions, so set there. Good advice on the mirror. It's tricks and experience like that that make jobs easier. Much appreciated!
 

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Discussion Starter #13
I ordered from Rock Auto. I typically find their prices a bit cheaper than Amazon, too, even with shipping. Thank you also for providing the torque specs. This helps a lot!
 

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One more question, please. Is this correct?

#1 back left (passenger side), #2 back middle, #3 back right, #4 front left, #5 front middle, #6 front right
 

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One more question, please. Is this correct?

#1 back left (passenger side), #2 back middle, #3 back right, #4 front left, #5 front middle, #6 front right
yes, I recall seeing it in valve adjustment instructions.
here are some posts confirming.
 

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Pull the #1 plug and look at it. If it's fouled then you have VCM issues. If it's burning nice and clean then you need to look elsewhere for the misfire.

I wouldn't drive with a misfire. You will burn up your catalytic converters, making repairs a LOT more costly.
 

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Discussion Starter #19
Well, it's looking ugly. The misfire on cylinder 3 correlates to the worst-looking plug. 1, 2, and 3, but especially 3 appear oil-fouled to me (happy to be corrected, of course) whereas 4, 5, and 6 were dry. Based on what I learned, I expected 4 and 6 to be the cleanest going in with perhaps 5 being a little less clean, and that's what it appeared to be. Oil was also low, which I suspect corresponds to some coming pass the piston rings on 1-3.

My VCMTuner II is presently in transit. I don't have plans to really drive the van until then and suspect I can put it in early this week. At 45k, the van is due for an oil change, coolant change, brake fluid change (a bit overdue, admittedly), and a set of new tires (just pile it on), so I'm taking care of it all at once in the next week or two. The shop's nearby, so no sense to add any oil in the meantime, I think, since it's not critically low.

My question to you fine folks would be whether you suspect this 2016 Odyssey with new plugs that once the tuner is installed, and the Techron fuel system cleaner is applied on a couple of tanks, I should be good to go or do you think there's any reasonable residual issue (piston rings, catalytic converter issues (no CEL for that), etc.).

Thank you for all the knowledgeable help. I appreciate you all very much.

Simon

159000

159001

159002

159003

159004

159005

159006
 

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nice capture of the plugs...
yup those look oily.

John Clark has mentioned in previous posts, that is all he has done for some customers and that set them straight.

If you're really concerned with the rings on 3 not freeing up, you can do the piston soak with some techron or berryman b12, by pouring some straight into the cylinder with the plugs out.

let it sit over night and shoot some compressed air with a rag covering the hole to blow out any residual concentrate that didn't drain into the oil pan.
don't want to create a hydro lock when you put the plugs back in.
another method is taking the fuse out for the injector and ignition, and bunting the engine to get the cleaner out of the combustion chamber while working the rings.
bit messy...

you will also need to do an oil change after this procedure.

another poster had good success with this piston soak method with over 200k miles, and it's what Honda did (decarbon) before the class action and recall.

to get a better idea of the VCM and how it works and why plugs 1-3 are fouled, check out pages 3281-3285 specifically 3 cylinder mode in the service manual linked below.
 
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