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Discussion Starter · #1 ·
Hello Odyclub,

TL;DR: How to diagnose and confirm VCM issues due to cylinder ring issues on rear bank at 175k miles despite new spark plugs from reading old plugs

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We have owned many Odys until this point - an 01 EX we sold with 500k miles still running, an 06 EX-L that got totaled with 450k (but still ran), two 08 EX-Ls currently in the family with over 250k miles each, and a neighbor's 08 LX with 280k that I still help maintain. I have personally performed 6 timing belt/WP replacements, hundreds of oil changes, and countless other maintenance items to various Odys over the years, so you could say I am familiar with these vans. So when I heard my friend was selling his one-owner (mostly) dealer-maintained 2012 Touring Elite, I jumped at the opportunity to buy it! With just 140k miles, based on our previous Ody experience, I figured it was "just broken in".

At first, it was love at first drive. The smoothness, quietness, and refinement over previous gens was night-and-day. We drove it with 5 people, 4 bikes, and a ton of gear from Houston, TX to Angel Fire, NM (1800 mi roundtrip) with no issue and in total comfort, all while returning 22MPG.

From my experience with the 06 and on vans, at some point in our ownership I bought a VCMuzzler II and installed it in this van to prevent potential future VCM issues. Various such other trips later, we had put about 35k miles on it and now sat at around 175k miles. Then the problems began.

My parents drove the van on another long drive and experienced the flashing CEL and codes P0300, P0301, P0302, and P0303. They were able to limp it home for me to diagnose.

My first step was to review the comprehensive maintenance history of the van. I did not find any indication of spark plug replacement in 175k, including with timing belt replacement around 105k when I would have expected it, so that was my first order of business. 6 brand new OE NGK DILZKR7A11G spark plugs later, I was hoping the issue was resolved. Unfortunately, it persisted. The issue seems most pronounced when the van is cold, and gets progressively better as it warms up. The van lacks power, and if you push it beyond very moderate throttle, the CEL flashes with the misfire codes and VSA failure. Once it warms up (after about 10 mins), you can push it fairly hard without the flashing CEL but it still lacks power. As a related aside, the catalytic converters were replaced with aftermarket parts by the PO within months before I bought the van.

Upon further research on this board, I came to know of the VCM issues commonly known for this gen on cylinders 4-6. Most recently, at least 3k miles after they'd been replaced, I took the 6 new spark plugs out to see if the rear bank was oil contaminated - see below. I swapped the front 3 with the rear 3 hoping the issue would at least temporarily be resolved; however the P0300, P0301, P0302, and P0303 came back right away.

At this point, my assumption is it's a VCM issue pertaining to the cylinder rings of the rear bank considering we've had the VCMuzzller II installed the last 2k+ miles, but the 170k plus prior miles, it has not been. The odd thing is, compared to previous Odys we've had which have consumed SUBSTANTIAL oil between oil changes (adding 5+ quarts after an oil change, but only getting 3 quarts out upon draining), this Ody consumes ZERO oil between changes. I fill 5+ quarts and get essentially the same out next oil change.

At this point, we just need the van fixed, and I am about ready to throw in the towel and have it diagnosed at the local stealership. I am still good friends with the original owner, so I figure we'll have the best leverage if he brings it back to the original dealership where he bought it, and if the cylinder rings need replacing, hopefully we can get some goodwill from Honda.

How can I try to diagnose this myself before bringing it to Honda? I am very DIY-oriented so I would like to try that first. I see lots of info on the board about what the issue is, but not much in terms of actually diagnosing/confirming it. Leak down test? Compression test? How does Honda diagnose it before tearing the engine apart?

I took pics of the (possibly) original spark plugs as well as the new ones after 3k in the hopes of learning something from the old school "read the plugs" approach.

I also found this interesting thread that resulted in the dealership initially diagnosing bad injectors on bank 2, but no confirmation from the OP after that: VCM issues - A gameplan

6 new spark plugs after 3k miles, in correct orientation with front of van at TOP of picture, and rear 3 at bottom:
Gas Electric blue Auto part Metal Fashion accessory


Closer view of combustion area:
Product Automotive tire Household hardware Auto part Engineering


Close-up of cylinders 1 or 2 without VCM:
Fluid Automotive tire Gas Liquid Electric blue


Close-up of one of the rear 3 cylinders (I didn't note which):
Hood Motor vehicle Automotive tire Automotive lighting Gas


6 old (possibly original) spark plugs prior to replacement - I lost track of the order in relation to cylinder, so they're in random order:
Water Liquid Drinkware Fluid Plastic bottle


Close-up of the old plugs:
Tableware Liquid Drinkware Fluid Water
 

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Best to use proper terminology
Sky Font Circle Electric blue Darkness


The proper cylinder numberings.

On your model year cylinders 5 and 6 are irrelevant for VCM.

Do note that other things can cause misfires as well.
At this point, my assumption is it's a VCM issue pertaining to the cylinder rings of the rear bank considering we've had the VCMuzzller II installed the last 2k+ miles, but the 170k plus prior miles, it has not been.
This does not really make a difference. Plus you aren't burning oil, which removes suspicion from rings.
 
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Hmm, interesting case... it's rare for 3 coils to go bad at once, but have you tried swapping front/rear coils to see if the misfire persists in the same cylinders?

I also wonder if this isn't a VCM problem, if you aren't burning any oil. I wonder if it might be related to the valves needing adjustment, although that shouldn't cause a misfire this bad.
 
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I doubt this is a VCM problem at all. Misfire could be caused by something else. Fuel injectors, valve adjustment, etc.
 
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Great post, details, and photos.
Yet, bullet points could be helpful for the disabled, like me. lol

Could a vacuum leak, in or out cause these codes? ? ?
Unlikely
Smoke test it anyway. To amuse everyone and myself. lol

Sorry, habit. If I may....

  • one-owner (mostly) dealer-maintained 2012 Touring Elite
  • With just 140k miles
  • I bought a VCMuzzler II and installed it in this van
  • 35k miles on it (muzzler)
  • now around 175k miles.
  • long drive and experienced the flashing CEL and codes P0300, P0301, P0302, and P0303
  • 6 brand new OE NGK DILZKR7A11G spark plugs later
  • issue seems most pronounced when the van is cold, and gets progressively better as it warms up.
  • van lacks power, and if you push it beyond very moderate throttle ...
  • Once it warms up (after about 10 mins), you can push it fairly hard without the flashing CEL but it still lacks power
  • catalytic converters were replaced with aftermarket parts by the PO within months before I bought the van
  • however the P0300, P0301, P0302, and P0303 came back right away
  • this Ody consumes ZERO oil
  • took pics of the (possibly) original spark plugs as well as the new ones after 3k in the hopes of learning - - - something .. [ This is huge in itself fwiw ]
And here we are.

= you can push it fairly hard [ ie throttle ] without the flashing CEL but it still lacks power
  • gets progressively better as it warms up.
  • catalytic converters were replaced with aftermarket parts

IMO. Clogged Cat / Exhaust.
Simple check

JMO
 
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Check you air intake tube for cracks too. Not sure it would cause all those specific misfire codes, but I have seen that cause the random misfire P0300 due to too much unmetered air getting in. I had to replace mine somewhere around 150k.
 

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Cylinder 3 new plug looks nasty for such low mileage.
Perhaps replace #3 and #4 cylinder plugs.
 

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Interesting information above. I have a 2011 Odyssey EXL with about 97500 miles and am having trouble with recent decrease of about 3 to 4 mpg. I took it to a fellow who was going to use his computer to diagnosis and it has been five days and haven't heard from him. Before that I took it to AutoZone and when they used computer it gave error message P0302 plus a couple other things. I left the print out in the car. I am not competent to do much to fix it but if anyone has suggestions I would really like to hear them. I haven't been driving very much in the last few months and wondered if that might have anything to do with the reason for the mpg decrease.
Also having a problem with heated drivers seat ... I turn it on and after a minute or two it goes off. Any one have a suggestion as to what might cause that?
I appreciate any help or suggestions.
What is a VCMuzzler?
 

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Discussion Starter · #12 ·
After reading further on the board, I am convinced the issue is due to carbon buildup, not bad rings. The fact that it does not burn any oil points to the rings being in good condition. More likely, in the 170k miles ran without a VCMuzzler, significant carbon has built up in the cylinders when VCM has been enabled. Although the last 1k miles the van was driven prior to being parked in its current state were highway miles with the VCMuzzler enabled, I am guessing this van qualifies as one of the more severe examples requiring a soak of the rings to remove some of the carbon buildup.

I am going to attempt to soak the cylinders first, before resorting to bringing to the dealership. Since the plugs only have 3k miles on them, surely I can just clean them up with electrical contact cleaner rather than lay out another $80 for another set of plugs?

Useful thread on the subject:
 

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You would want to try some spirited driving to help clean some of it up. Drive it like you stole it for a while and see if that helps.

VCM does not cause the rings to go bad really. It causes them to get stuck because of the buildup. It's not permanent damage.
 
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2016 Ody SE, white diamond pearl, running boards, roof rack, trailer hitch, door bummers, 20%tint
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16 Ody SE w/43k (purchased Jan-2021 w/38k). Just changed my plugs yesterday, as a precursor to vcm muzzle (vcm tuner II).

Work I'm doing is all preventative, motor is perfect but willing to try this approach after reading various the Honda service Bulletins, and online discussions - should cause zero harm otherwise it wouldn't be recommended, if it does i can always remove it. I did notice a jump in volts (Scangauge 2), but that's from the new spark plugs. I'm going to use the Scangauge further in terms of before and after (but vcm muzzle as of now is still in the garage/ not installed yet).

Again - My original OEM plugs were working normal and looked as these should when compared to the manufacturer/NKG worn plug chart. Hope this helps.
 

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16 Ody SE w/43k (purchased Jan-2021 w/38k). Just changed my plugs yesterday, as a precursor to vcm muzzle (vcm tuner II).

Work I'm doing is all preventative, motor is perfect but willing to try this approach after reading various the Honda service Bulletins, and online discussions - should cause zero harm otherwise it wouldn't be recommended, if it does i can always remove it. I did notice a jump in volts (Scangauge 2), but that's from the new spark plugs. I'm going to use the Scangauge further in terms of before and after (but vcm muzzle as of now is still in the garage/ not installed yet).

Again - My original OEM plugs were working normal and looked as these should when compared to the manufacturer/NKG worn plug chart. Hope this helps.
And why haven't you installed the vcm muzzler? The sooner you do, the better.
 

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Do you have a fuel pressure gauge? That’s the first thing I do when I have a driveability problem. Next would be swapping coils front to back. If the codes swap spots with the coils, you have faulty coils. If not, it sounds like you have a faulty cat converter.
 

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And why haven't you installed the vcm muzzler? The sooner you do, the better.
Yep, will install the muzzle just prepping for it. Read too many other posts that revealed problems because they put it on without doing maintenance first. So I've changed my nkg plugs, new AMG battery, mobil1 oil, drain/fill atf, installed Scangauge-2 that will also measure before and after differences related to my new...vcm tuner II. 16Ody SE currently has zero issues so this is all preventative work.

However, wanted to share my picture of plugs since mine looks similar to the original poster here... seems like a lot of people are just guessing but failed to review the manufacturer's spark plug chart to determine whether or not there's a related problem. NKG has taken the guess-work out of the equation, if you take a look at their worn plug chart.
 

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Hello Odyclub,

TL;DR: How to diagnose and confirm VCM issues due to cylinder ring issues on rear bank at 175k miles despite new spark plugs from reading old plugs

---

We have owned many Odys until this point - an 01 EX we sold with 500k miles still running, an 06 EX-L that got totaled with 450k (but still ran), two 08 EX-Ls currently in the family with over 250k miles each, and a neighbor's 08 LX with 280k that I still help maintain. I have personally performed 6 timing belt/WP replacements, hundreds of oil changes, and countless other maintenance items to various Odys over the years, so you could say I am familiar with these vans. So when I heard my friend was selling his one-owner (mostly) dealer-maintained 2012 Touring Elite, I jumped at the opportunity to buy it! With just 140k miles, based on our previous Ody experience, I figured it was "just broken in".

At first, it was love at first drive. The smoothness, quietness, and refinement over previous gens was night-and-day. We drove it with 5 people, 4 bikes, and a ton of gear from Houston, TX to Angel Fire, NM (1800 mi roundtrip) with no issue and in total comfort, all while returning 22MPG.

From my experience with the 06 and on vans, at some point in our ownership I bought a VCMuzzler II and installed it in this van to prevent potential future VCM issues. Various such other trips later, we had put about 35k miles on it and now sat at around 175k miles. Then the problems began.

My parents drove the van on another long drive and experienced the flashing CEL and codes P0300, P0301, P0302, and P0303. They were able to limp it home for me to diagnose.

My first step was to review the comprehensive maintenance history of the van. I did not find any indication of spark plug replacement in 175k, including with timing belt replacement around 105k when I would have expected it, so that was my first order of business. 6 brand new OE NGK DILZKR7A11G spark plugs later, I was hoping the issue was resolved. Unfortunately, it persisted. The issue seems most pronounced when the van is cold, and gets progressively better as it warms up. The van lacks power, and if you push it beyond very moderate throttle, the CEL flashes with the misfire codes and VSA failure. Once it warms up (after about 10 mins), you can push it fairly hard without the flashing CEL but it still lacks power. As a related aside, the catalytic converters were replaced with aftermarket parts by the PO within months before I bought the van.

Upon further research on this board, I came to know of the VCM issues commonly known for this gen on cylinders 4-6. Most recently, at least 3k miles after they'd been replaced, I took the 6 new spark plugs out to see if the rear bank was oil contaminated - see below. I swapped the front 3 with the rear 3 hoping the issue would at least temporarily be resolved; however the P0300, P0301, P0302, and P0303 came back right away.

At this point, my assumption is it's a VCM issue pertaining to the cylinder rings of the rear bank considering we've had the VCMuzzller II installed the last 2k+ miles, but the 170k plus prior miles, it has not been. The odd thing is, compared to previous Odys we've had which have consumed SUBSTANTIAL oil between oil changes (adding 5+ quarts after an oil change, but only getting 3 quarts out upon draining), this Ody consumes ZERO oil between changes. I fill 5+ quarts and get essentially the same out next oil change.

At this point, we just need the van fixed, and I am about ready to throw in the towel and have it diagnosed at the local stealership. I am still good friends with the original owner, so I figure we'll have the best leverage if he brings it back to the original dealership where he bought it, and if the cylinder rings need replacing, hopefully we can get some goodwill from Honda.

How can I try to diagnose this myself before bringing it to Honda? I am very DIY-oriented so I would like to try that first. I see lots of info on the board about what the issue is, but not much in terms of actually diagnosing/confirming it. Leak down test? Compression test? How does Honda diagnose it before tearing the engine apart?

I took pics of the (possibly) original spark plugs as well as the new ones after 3k in the hopes of learning something from the old school "read the plugs" approach.

I also found this interesting thread that resulted in the dealership initially diagnosing bad injectors on bank 2, but no confirmation from the OP after that: VCM issues - A gameplan

6 new spark plugs after 3k miles, in correct orientation with front of van at TOP of picture, and rear 3 at bottom:
View attachment 166357

Closer view of combustion area:
View attachment 166358

Close-up of cylinders 1 or 2 without VCM:
View attachment 166359

Close-up of one of the rear 3 cylinders (I didn't note which):
View attachment 166360

6 old (possibly original) spark plugs prior to replacement - I lost track of the order in relation to cylinder, so they're in random order:
View attachment 166361

Close-up of the old plugs:
View attachment 166362
I am in a similar position. I had an oil change at dealership & CEL light appeared after few mins of driving. I had all 6 spark plugs replaced which temporarily solved the problem. After few weeks, CEL appeared again & this time it was flashing. This time, replaced ignition coil & spark plug which provided temporarily remedy. Drove for few weeks & CEL appeared again & flashing. I can smell gas in oil as well. My next steps are:
1) Compression test
2) Check valve adjustments/clearance
3) Rotate the crank & visually inspect the valves movement especially for cylinders 1,2 & 3 & rocker arms.
4) Lastly, smoke test
Also, I read somewhere if you can spot carbon buildup on your engine cover cap, the valves may need to be adjusted.
To my best understanding, the VCM is regulated by oil pressure & uses rocker arms to apply presure on valves to stay close during VCM engagement. Since it is a pressure driven system, the viscosity of oil, cold weather & geometry of moving parts within the VCM can also foul pla due to pressure difference. It seems like a mechanical problem & maybe hard or time consuming through OBD2 scanning tools.
 

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Did you read at least the 1st post of the VCM Mega Thread? If you disable VCM then you don't have to worry about that system activating and deactivating. You run on all 6 cylinders all the time. Smelling gas in the oil sounds like it might be a VCM induced symptom.
 

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Did you read at least the 1st post of the VCM Mega Thread? If you disable VCM then you don't have to worry about that system activating and deactivating. You run on all 6 cylinders all the time. Smelling gas in the oil sounds like it might be a VCM induced symptom.
I had the muzzler installed at roughly 138K. These
Odysseys are notorious for misfiring & it seems like I bought a wrong vehicle. Over all, I am at over 8 grand since the purchase which was last year in October. I wish if I have known these issues before :(
 
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