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Discussion Starter · #1 · (Edited)
This thread will explain all the key details regarding VCM. Rather than re-explaining VCM to every new forum member, they can simply be directed here.

Although this is posted in the 2005-10 Odyssey forum, the information here will apply to all Odysseys 2005 and newer.

If you have an Accord, there is a similar thread in the Accord forum with information more tailored to it:

What is VCM?
VCM stands for Variable Cylinder Management. It is a technology introduced in 2005 that is present in many Honda V6 engines. It shuts off some cylinders in the V6 in situations where the full power of all cylinders is not needed in order to save fuel. This is accomplished by using a solenoid controlled by oil pressure to unlock the cam followers from the rockers, which closes the valves and prevents them from opening throughout the piston stroke, stopping the combustion cycle.

Besides the mechanical components in the engine to allow VCM operation, there are other components in the system. The most important component to know about is the active control engine mounts. When cylinders are disabled, it creates vibration from the motor, which the active mounts are designed to dampen so that you can't feel it in the cabin. Another part of the system is active noise cancellation (ANC), which cancels noise from VCM by playing white noise through the vehicle's speakers.


Does my Odyssey have VCM?
Honda introduced VCM in the 2005 model year beginning with the 2005 Odyssey, and it has been used in Odysseys and several other V6 Hondas ever since. However, there are some Odysseys that don't have VCM in the 3rd generation (2005-10). Here is a list of Odysseys that are equipped with VCM:

2005-2010 EX-L and Touring models only (unless the seats have been swapped, leather seats = VCM-equipped)


- An easy way to identify if your 2005-10 Odyssey has VCM besides the seat material is the sticker on the plastic engine cover.

If you have a standard engine without VCM, your engine cover will look like this:

163233


2005-2007 Odysseys with VCM will have an engine cover that looks like this (notice the i-VTEC instead of VTEC and the VCM font below that):
163234


2008-2010 Odysseys with VCM will have an engine cover that looks like this (same as the last one except the VCM font is more prominent):
163235


2011+ all trim levels

Are there differences in the VCM systems?
Yes. As of June 2021, there are 3 different revisions of VCM:

VCM-1: The initial revision of VCM. It is capable of shutting off the rear bank of cylinders (cylinders 1-3).

VCM-2: The second and most problematic revision of VCM. It is capable of shutting off the rear bank of cylinders (cylinders 1-3) just like VCM-1, and it is also capable of shutting off one cylinder (cylinder 3) in the rear bank and one cylinder in the front bank (cylinder 4) at the same time, which means that VCM-2 affects an extra cylinder compared to VCM-1.

VCM-3: The third and newest revision. It is similar to VCM-1 in that it is only capable of shutting off cylinders 1-3.

Different Odysseys are equipped with different VCM revisions:


2005-2007 Odysseys that are VCM equipped (see the last section to find out if yours is equipped with VCM) have VCM-1

2008-2010 Odysseys that are VCM equipped (see the last section to find out if yours is equipped with VCM) have VCM-2

All 2011-2017 Odysseys have VCM-2

All 2018+ Odysseys have VCM-3

How can I tell when VCM is active?
You may be interested in figuring out when VCM is active. On 2005-17 Odysseys, you may be able to feel/hear it as there may be vibrations. You will also see the green ECO light illuminate on the dashboard. However, do not rely on only the ECO light, as it is possible for the light to be on even when VCM is not active. On 2018+ Odysseys, it's a little more tricky, as there is no ECO light like the older models. You'll just have to listen carefully and feel for it.

A common misconception is the ECON mode button and the corresponding dash light on 2018+ Odysseys controlling VCM. The ECON mode has nothing to do with VCM. It affects things like shift points to increase fuel economy.


What's so bad about VCM?
While VCM is a great idea in theory, in practice it has some issues.

During VCM operation, the valves on the disabled cylinders are closed off while the piston continues to move up and down. This creates a vacuum effect in the cylinder, allowing some oil to get sucked past the piston rings into the combustion chamber. This oil continues to collect in the combustion chamber until VCM disengages, at which point the cylinder must burn off the oil before resuming normal operation. This is one way VCM can cause burning oil.

When VCM is used repeatedly for long periods of time, it can also cause damage to the piston rings, allowing oil to get past them into the combustion chamber even when VCM is not operating. This is another way VCM can cause burning oil.

This oil burning can cause oil fouling of the spark plugs, leading to misfires. The oil burning combined with the misfires will destroy your catalytic converter (not cheap to replace!) over time.

Besides these engine problems, VCM operation also puts stress on the active control engine mounts, causing them to wear out. These engine mounts are not cheap. One mount alone (just the part, no labor included) can cost several hundred dollars.

Simply put, VCM is gambling on your engine for a gain of 1-2 MPG at best. Gas is cheaper than an engine, especially given the very slight MPG difference.

This video by speedkar99 shows a VCM engine taken apart so you can see how the parts of the system work together and how they cause problems. If you're interested, take a look:

It's generally believed that VCM-3 is more refined and tweaked compared to its predecessors, and is therefore less problematic. VCM-3 has not been used in Odysseys for too long. So it's your call on whether you want to leave it alone or not. It will still eat up motor mounts at the very least.

I've owned several VCM vehicles and never had any issues. What's going on here?
These VCM problems are not consistent. Many factors play in to what (if any) problems you may see and at what severity. People who drove their vehicles hard when they were new have typically had fewer issues later on. People with VCM-1 and VCM-3 may experience fewer problems simply because there are fewer situations where VCM can engage and it will stay engaged for less time. But as mentioned in the previous section, the MPG gained is minimal at best, so what's the point in risking it?

If VCM is so bad, why does Honda still use it? Will Honda help me with my VCM related problems?
Honda would not spend the time and money to develop VCM unnecessarily. They're using VCM because it gets them CAFE credits from the EPA if they can maximize MPG on their vehicles. Without it, they'd be hit by penalties.

Honda still refuses to acknowledge any problems with the VCM system. While there was a class action lawsuit against them regarding VCM, they settled it by offering an extended warranty on the piston rings for 2008-2013 vehicles equipped with VCM. This warranty is now well past the expiration if you were lucky enough to be covered by it. 2008-2013 doesn't cover a large chunk of VCM vehicles that are still affected, especially 2014-2017 Odysseys. While Honda dealerships will sometimes offer goodwill consideration for a piston ring replacement job on these vehicles, the cost can still be somewhat high.


And for what it's worth, Honda has been phasing out VCM by simply phasing out the J-series V6 altogether. They're moving more towards the turbocharged 2.0L engine as seen in the 10th generation Accord. No more V6 = no more VCM. But then you get all the fun associated with a turbocharged engine. You win some, you lose some.

Honda has a new DOHC V6 design that debuted in the 2021 Acura TLX Type-S, which is not equipped with VCM. It remains to be seen what this means for VCM.
Okay. After reading this, I don't want VCM enabled on my vehicle. What can I do?
Good choice. Unfortunately, with the exception of VCM being inactive whenever a check engine light is on, Honda cannot include any built in disable switch for VCM because they wouldn't get the CAFE credits if they did. This means you must install an aftermarket device. However, installation is quite simple and an inexperienced user could likely install one in 15 minutes or less. All the devices come with good instructions for installation and don't require much. There are 5 different recommended disable devices (also known as VCM "muzzlers"). Here they are, arranged from least expensive to most expensive along with where you can get them:
MaxMuzzler - DM user @maxud


VCMuzzler II - DM user @verbatim

VCMTuner - vcmtuner.com

S-VCM - svcmcontroller.com

VCM Tuner II - vcmtuner.com


There are some differences between these disable devices, which will be explained in a later section.

How do these disable devices work?
All these VCM disable devices work on the same concept: altering the coolant temperature reading sent to the computer.

By doing this, the computer thinks the engine is not warmed up yet, so it does not engage VCM. However, this does not affect the actual operating temperature of your engine, only the temperature the computer sees. Also, only the reading for one of the temperature sensors is altered. The other is kept intact, so cooling fans will still operate normally. In fact, the only difference you'll notice is that your coolant temperature gauge will sit slightly lower than before when fully warmed up. However, there is no need to worry, as you will still be able to tell when your car is overheating.


Are there differences between the disable devices?
Yes. There are differences in features and compatibility.

The most important difference is that each disable device has a 2005-2006 version and a 2007+ version. These are not interchangeable, so if you have a 2005-2006 Odyssey, you will need the 2005-2006 version, and if you have a 2007+ Odyssey, you will need the 2007+ version.

Also, while all the disable devices work on the same concept, they accomplish it in different ways.

There are two categories for muzzlers: passive and active.

Passive muzzlers are good because they're cheaper, but they also require manual adjustment as the climate changes and are more like VCM suppressors rather than true VCM disablers, as they only disable VCM 90-95% of the time. VCM may come on briefly if you are in traffic.

Active muzzlers are more expensive than passive muzzlers but they are completely automatic. After installation (which is slightly more difficult as you must run a wire to the battery), adjustment is completely automatic with no user input required, and VCM is disabled 100% of the time. Active muzzlers also usually are capable of turning themselves off in a real overheating situation so that you will be able to see the car overheating on the temperature gauge faster. The VCMTuner II also supports turning itself off if the car is detected to be idling. This is useful for some service procedures such as idle relearns where the computer needs an accurate temperature reading.

Generally active muzzlers are recommended, but if you cannot purchase an active muzzler for some reason, the passive muzzlers are still a great option (better than nothing) if you can live with adjusting it and VCM coming on occasionally.

If you have a 2005-2010 Odyssey and choose to convert from the expensive active control engine mounts to the standard passive engine mounts, an active muzzler is required, as the passive mounts will be destroyed when VCM occasionally activates with a passive muzzler.

The following muzzlers are passive muzzlers:
MaxMuzzler (adjustable through resistance dial)
VCMuzzler II (adjustable through included swappable resistors)
VCMTuner (adjustable through resistance dial)

The following muzzlers are active muzzlers:
S-VCM
VCMTuner II

The choice is up to you which type of muzzler and which muzzler you get for your vehicle. Consider the various factors to make your decision.


Will installing a VCM disable device void my warranty?
Installing a VCM disable device should not void your warranty. Many members have left their disable devices on when taking their vehicles to the dealership for service, and it has either gone unnoticed or noticed and ignored. In some cases the dealerships have even endorsed the device. However, if you are concerned about it, you can easily remove the disable device before you take it in for service.

My car already has damaged piston rings, fouled spark plugs, and/or misfires. What can I do from here?
Even if your car already has one or more of those issues, it's not too late. Installing a VCM disable device and replacing all of the spark plugs should allow the piston rings to free up over time, and your engine should return to normal operation with VCM no longer engaging. Some may recommend adding some Chevron Techron to your gas tank and driving the car aggressively to help free up the piston rings. The bottom line is that you most likely do not need to pay for an expensive piston ring replacement job.

Can I trust my engine to be reliable after disabling VCM?
Yes. As long as you do regular maintenance, once you disable VCM, your engine will be just as reliable as a non-VCM engine. Although it is worth mentioning that some VCM-2 engines can be prone to premature camshaft wear even when VCM is disabled.
 

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Great write up! Hopefully it will be sticky. Needs to be in the 11-17 section too with the weekly run of post there are lately with VCM issues.
 

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Discussion Starter · #5 ·
Great write up! Hopefully it will be sticky. Needs to be in the 11-17 section too with the weekly run of post there are lately with VCM issues.
Unfortunately, unless I copy the full thread content to 11-17 forum, there's no way it can be in both places. I'd rather not do that, because that would mean 2 separate threads for me to maintain. Although one thing I could do is post a thread in there that just links to here. I'll probably do that.
 

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Thank you for doing this WiiMaster! Excellent write-up.

Perhaps someday I will write one for parasitic battery drains and side door rear latch issues!
 

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We should have our beloved moderator put this up top in the Stcky section. It is a nice companion to Verbatim's thread that is there.
 

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Discussion Starter · #9 ·
Perhaps someday I will write one for parasitic battery drains and side door rear latch issues!
If I don't beat you to it :p
 
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Thank you for this write up, I have a VCM Tuner II that arrived this week and have been waiting to install it, I felt like I needed to understand it better. This article cleared up the key points I was concerned about. Thanks again.
 

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Discussion Starter · #11 ·
Thank you for this write up, I have a VCM Tuner II that arrived this week and have been waiting to install it, I felt like I needed to understand it better. This article cleared up the key points I was concerned about. Thanks again.
This is what I like to hear.
 
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This is a necessary sticky. When I bought my Ody and jumped on these forums, VCM info was plentiful, yet vague. After 2 hours of reading threads I still didn't know it was a bad thing, nor did I know that my EX didn't even have it. 2 hours.
 

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When piston goes up and down, there are SMALL amount of oil that "seeps" through the ring. Of course, the piston ring does NOT ride on dry wall, so wall has to have oil on it.

This small amount of oil gets burned up normally. However, when VCM kicks in, the fuel injector turns off (so no fuel goes into the chamber as expected) but not only that, all 4 valves are disconnected and do not move and remain closed and as piston goes up and down the cylinder, vacuum is created thus sucking more and more oil into the chamber through the SLIGHT gap in the piston ring. Once you move out of the VCM, fuel is put into the chamber and normal combustion happens. However, at this time, there are a lot more oil in the chamber than usual because all those oil has pooled in the chamber due to vacuum generated.

Now, VCM-1 is a lot less aggressive because there is only v6 or i3 mode. and in i3 mode, car is just not generating enough to move the heavy Ody except either down hill or on really flat part of the highway which means that it is keep getting out of VCM mode thus burning off the oil thus this generation is least affected by the issue.
VCM-2 added 4-cylinder operation which may be able to keep VCM operational for longer causing a LOT more favorable condition for oil burning when coming out of VCM.
I am not familiar with VCM-3 I DO believe they went back to 3 cylinder operation and no longer have 4 cylinder operation.
 

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When piston goes up and down, there are SMALL amount of oil that "seeps" through the ring. Of course, the piston ring does NOT ride on dry wall, so wall has to have oil on it.

This small amount of oil gets burned up normally. However, when VCM kicks in, the fuel injector turns off (so no fuel goes into the chamber as expected) but not only that, all 4 valves are disconnected and do not move and remain closed and as piston goes up and down the cylinder, vacuum is created thus sucking more and more oil into the chamber through the SLIGHT gap in the piston ring. Once you move out of the VCM, fuel is put into the chamber and normal combustion happens. However, at this time, there are a lot more oil in the chamber than usual because all those oil has pooled in the chamber due to vacuum generated.

Now, VCM-1 is a lot less aggressive because there is only v6 or i3 mode. and in i3 mode, car is just not generating enough to move the heavy Ody except either down hill or on really flat part of the highway which means that it is keep getting out of VCM mode thus burning off the oil thus this generation is least affected by the issue.
VCM-2 added 4-cylinder operation which may be able to keep VCM operational for longer causing a LOT more favorable condition for oil burning when coming out of VCM.
I am not familiar with VCM-3 I DO believe they went back to 3 cylinder operation and no longer have 4 cylinder operation.
Just confirming that you are right. VCM-1 and VCM-3 are V6 or slant-3 (6-cylinder or 3-cylinder) modes only.

VCM-2, which was available from 2008-2017, was the only one that also had a 4-cylinder mode.
 
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So my neighbors 2010 with body colored side view mirrors and leather means it has a VCM motor? I will guess a VCM,

Is there a way to identify a VCM motor under hood easily compared to non VCM?

Don't recall my Touring having a VCM badge underhood,

TIA
 

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[QUOTE="WiiMaster, post: 2438268, membe (see the last section to find out if yours is equipped with VCM) have VCM-1

Did i miss the last last section describing how one would know if they have a VCM motor?

Please feel free to link / copy quote.

Yeah messed up the quote. I'm trying.
 

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Awesome writeup. I have stickied it here but the stickies in this gen are a mess. I need to clean them up.
 

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So my neighbors 2010 with body colored side view mirrors and leather means it has a VCM motor?
Yes it does - as soon as you have leather upholstery, that means you have an EX-L or higher and that means a VCM-equipped engine.

I will guess a VCM,

Is there a way to identify a VCM motor under hood easily compared to non VCM?

Don't recall my Touring having a VCM badge underhood,

TIA
For model years 2008-2017, there is a VCM logo either printed on a label on the engine cover (2008-2010) or molded directly into the engine cover (2011-2017). For 2018+, the VCM logo is replaced by the "Earth Dreams" logo. I guess Honda decided they didn't want to brag about VCM after 2017.

It is oddly easy to not notice even though it's right there in the middle of the engine bay (this is a 2010 Ody).

162620
 
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Discussion Starter · #19 ·
For model years 2008-2017, there is a VCM logo either printed on a label on the engine cover (2008-2010) or molded directly into the engine cover (2011-2017).
It looks like the 05-07s have the VCM logo as well, it's just a little less obvious:
162623


Also, the non-VCM will be VTEC rather than i-VTEC. Here's my Ody's non-VCM cover for comparison:
162624


Awesome writeup. I have stickied it here but the stickies in this gen are a mess. I need to clean them up.
Definitely. A few stickies with dead links are simply taking up space.
 
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With a VCM muzzler installed, would it ever be necessary to disconnect the muzzler to exercise the VCM system? Could there be certain parts like solenoids or what not that could get stuck after not operating for an extended period of time? (I have the tuner II on my 2011 ody)

This is more of a theoretical question: Why couldn’t the VCM system be designed to not decouple the valves from the camshaft. Just have the dead cylinders suck in fresh air, compress it and exhaust it out with no fuel or combustion air? This way there would be no vacuum sucking oil up the wrong way past the rings.


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