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Discussion Starter #1
Just trying to get some minds together to discuss Honda's VCM system. I'm trying to figure out what actually controls it. Is it the PCM? The reason I ask is that the AT version of the accord shares a ton of engine parts with the 3.5 L acura TL. As most of you are aware the TL does not have VCM. so I would like to try to get a discussion going on this subject..
 

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Found this so I just copy/paste.

ariable Cylinder Management (VCM) is Honda's term for a variable displacement technology. It uses the i-VTEC system to disable one bank of cylinders during specific driving conditions (for example, highway driving) to save fuel. The 2008 Accord takes this a step further allowing the engine to go from 6 cylinders, down to 4, and further down to 3 as the computer sees fit. Honda's VCM uses overhead cams as opposed to DaimlerChrysler's Multi-Displacement System and General Motors' Active Fuel Management pushrod systems.

It uses a solenoid to unlock the cam followers on one bank from their respective rockers, so the cam follower floats freely while the valve springs keep the valves closed. The engine's drive by wire throttle allows the engine management computer to smooth out the engine's power delivery, making the system imperceptible. Vehicles equipped with VCM are equipped with an "ECO" indicator on the dashboard which corresponds to the VCM system's operation. Vehicles equipped with VCM also include Active Noise Cancellation (ANC) and Honda's Active Control Engine Mount (ACM) system. The ANC and ACM systems work in cooperation to cancel both noise and vibration that could occur in relation to the cylinder deactivation process. The ANC system uses the audio speakers to cancel out noise by using an opposite phase sound.
 

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VCM is a stupid piece of shit system which is primarily unnecessary. They could have gotten better results with a new 6 speed or 7 speed automatic transmission with a really tall 6 and/or 7th gears for excellent highway mileage.

My reasoning is my experience with my 6-6 and the belief that if they made the 6th gear operate at 1,750rpm when driving 65mph, the car would easily return 28-30 mph on the highway and have all of the low end torque one could desire for reasonable, daily commuting.
 

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My reasoning is my experience with my 6-6 and the belief that if they made the 6th gear operate at 1,750rpm when driving 65mph, the car would easily return 28-30 mph on the highway and have all of the low end torque one could desire for reasonable, daily commuting.
Agree to a big degree on this. The problem you have is there really is two groups. One for pure performance would actually want shorter gears across which would optimize 1/4 times, etc. The other group thinks what you said...so they meet in the middle. However, I agree because whenever I'm driving on the highway its revving pretty high IMO and you could get so much better gas mileage if the engine wasn't revving high. The interesting this is the 6-6 actually is revving lower at highway speeds (well most speeds) than lets say an Si. I couldn't believe where that thing was cruising at when driving one on the highway.

If you are doing a lot of highway driving and want to optimize, I completely agree on a tall, long 6th gear (or higher if they made one for the accord) to cruise at. One thing that never completely sold me (or really anyone if looking at the figures) is the VCM's benefit. The difference was so small between that and a 6-6 (or even the i4 if you want to get technical) that it was an easy choice for me.
 

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the auto VCM actually has slightly better fuel economy. with gas forecast to surpass the $4 mark by spring, econ. is important.
 

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VCM is a stupid piece of shit system which is primarily unnecessary. They could have gotten better results with a new 6 speed or 7 speed automatic transmission with a really tall 6 and/or 7th gears for excellent highway mileage.

My reasoning is my experience with my 6-6 and the belief that if they made the 6th gear operate at 1,750rpm when driving 65mph, the car would easily return 28-30 mph on the highway and have all of the low end torque one could desire for reasonable, daily commuting.
I agree with you to a point . VCM is just one tool to get some better mpg but it does have some side affects compared to non VCM honda/Acura as you due lose performance type VTEC and adds more complexity to the powertrain system.
On the gearing you have to be careful to not have rpm to low that it lugs and ends up being worse but for sure a 6 speed would of improved on the 5AT . Also it would be nice if VCM was a option item .

I think the main thing is Honda Accords were always marketed for most part as eco/mpg friendly so they just added the VCM and didn't care about any negatives it brings in . You want more sports orientated vehicle, get the 6MT coupe .

Hopefully they will follow what Odyssey features (VCM + 6AT ) , in next versions of Accord .

Since Acura is more high end they don't care about VCM as you need 91 fuel so cost is back issue with higher end Acura line, it more performance/luxury type vehicles .
 

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I am not a fan of these types of systems on engines. I think it is too complicated with too many areas where things can go wrong. In the end the mpg savings is not worth the long term troubles that can occur.

Back in the day Cadillac attempted this shit system which was a disaster! In 1981 they tried the 4-6-8 system, which only lasted that 1 year.

I understand back in the day the technology was not as good as it is now, but I think that too many things going on the same time is just having more things to go bad.
 

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the VCM is about the only think I really like about my Accord. There's no way I could pull down the 31.5 highway mpg figures that I am without it.
 

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Discussion Starter #9
Ok, I think for the most part we can all agree VCM is nothing more than a MPG gimmick. After reading posts not only here but on other websites it comes to a conclusion of not wanting to fully redesigning the transmission, but just slapping the same tranny with a engine that can cut certain cylinders.

Now this leads me to my original question. With so many parts being shared by both the Accord V6 and the base Acura RL , and most of those that aren't shared between the AT version are shared between the Acura and the Accord MT. Now with that being said let's get this out of the way...I don't want this thread being turned into if you wanted "X" you should have bought "X". To me its not about that, its about tinkering. So let's think about what's needed to get rid of what I believe is a performance robbing feature.
 

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Ok, I think for the most part we can all agree VCM is nothing more than a MPG gimmick. After reading posts not only here but on other websites it comes to a conclusion of not wanting to fully redesigning the transmission, but just slapping the same tranny with a engine that can cut certain cylinders.

Now this leads me to my original question. With so many parts being shared by both the Accord V6 and the base Acura RL , and most of those that aren't shared between the AT version are shared between the Acura and the Accord MT. Now with that being said let's get this out of the way...I don't want this thread being turned into if you wanted "X" you should have bought "X". To me its not about that, its about tinkering. So let's think about what's needed to get rid of what I believe is a performance robbing feature.
Your talking about 2 entirely different things , VCM is not a gimmick , it does what it says and that it helps in mpg on HW, or in conditions were it runs in 4-3 cylinder modes .
The transmission is another issue, both can be combined and are .

Your not going to some how turn the VCM engine into a MT V6 feature type engine .
 

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Discussion Starter #11
Your talking about 2 entirely different things , VCM is not a gimmick , it does what it says and that it helps in mpg on HW, or in conditions were it runs in 4-3 cylinder modes .
The transmission is another issue, both can be combined and are .

Your not going to some how turn the VCM engine into a MT V6 feature type engine .
Ed, maybe I came across wrong with my post..its almost as if Honda didn't want to spend the resources to fully develop the VCM feature. If you look at the redesign Odessey it takes not only the VCM design but also adds in a 6 speed AT.

Now on to the second point. I'm not looking into turning a VCM engine into a MT. What I have said is the Accord AT engine shares a ton of parts (minus the pistons) with the Acura RL base. Those parts that are different are found in the MT engine in the Accord. If you don't believe me have a look. Bring up the part sheets and have a look. They don't share the same part numbers just because Acura didn't feel like making new ones. The front and rear cylindar blocks are identical as the ones found on the Z3. the parts that are different on the lower engine block are identical to those on the MT Z3.

Now I haven't had time to check the entire AT on both the Accord and the TL, but what I have checked have been identical. That share the same transmission housing, and so far every part I have checked. So this less me to believe so far the transmissions are identical. Now from what I can see in the service manual out looks like the PCM tells the engine when to go into VCM mode and when to not.

These have been my findings so far. Could replacing these parts and tossing in a ECM from a 3.5 L TL get rid off VCM?
 

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Odds are that after Honda added the 6AT to the '11 Odyssey, they will probably add it to the '13 Accord. They wouldn't add that feature between gen changes.
 

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Discussion Starter #13
For sure.. It looks like the Accord was the test bed for VCM. Now the reason I'm looking at getting rid of it is not because I think fuel economy is better without it, but for performance reasons.
 

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Ed, maybe I came across wrong with my post..its almost as if Honda didn't want to spend the resources to fully develop the VCM feature. If you look at the redesign Odessey it takes not only the VCM design but also adds in a 6 speed AT.

Now on to the second point. I'm not looking into turning a VCM engine into a MT. What I have said is the Accord AT engine shares a ton of parts (minus the pistons) with the Acura RL base. Those parts that are different are found in the MT engine in the Accord. If you don't believe me have a look. Bring up the part sheets and have a look. They don't share the same part numbers just because Acura didn't feel like making new ones. The front and rear cylindar blocks are identical as the ones found on the Z3. the parts that are different on the lower engine block are identical to those on the MT Z3.

Now I haven't had time to check the entire AT on both the Accord and the TL, but what I have checked have been identical. That share the same transmission housing, and so far every part I have checked. So this less me to believe so far the transmissions are identical. Now from what I can see in the service manual out looks like the PCM tells the engine when to go into VCM mode and when to not.

These have been my findings so far. Could replacing these parts and tossing in a ECM from a 3.5 L TL get rid off VCM?
The differences are in the heads(rocker shaft bridge an holder assembly), cams ,rockers arms and in ECU . so yes if you changed all these you may have your Non VCM version. the thing is the ECU is highly integrated into can bus which runs every other feature in the vehicle. Meaning if the TL ECU and the Honda don't have same electronic features you probably run into issues were things don't work, also harness will be different too .
Features like paddle shifter and a different AT shifter not sure how that would be affected on a honda.
The list above of parts is pretty high as is , price wise . Also remember the ECU and keys need reprogramming to work together , most likely need dealer to do this if they will .
 

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Discussion Starter #15
Ed, I have a local junkyard ready to sell me a ECM with matched keys from a 2009 base TL. they stand behind their products and have said if the ECM and keys are not a match they will pay to have it matched. As I said, cost to me isn't the issue, it's the fun of making something. I also forgot to mention three mounts would have to be changed since VCM will be removed. I figured selling most of these parts could help curb three cost some. And thanks for keeping this thread civil. :)
 

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VCM is all about decreasing pumping losses. That's it's trick to improving highway fuel mileage. By forcing the engine to run on 3 or 4 cylinders, it causes the engine to STRAIN. It actually forces the engine to strain quite heavily. Regardless of VCM, the engine must still produce the same 30-40 hp to push the car down the road at 60- 80 mph. Right? But with VCM, the engine is forced to make that same 40 hp from only 1.75 liters instead of 3.5 liters. So what is the benefit? This benefit is that the computer must open the throttle body much MORE. This in turn decreases the vacuum inside the intake manifold which directly decreases the pumping loss. That's the big deal! Less pumping loss translates to better fuel economy.

To me, the big question is does this slight increase in efficiency really offset the loss of having just one camshaft lobe. VCM engines are supposed to get about 2 mpg better on the highway but the lack of true VTEC also adds about 3/4's of a second to its 0-60 time.
 

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VCM is all about decreasing pumping losses. That's it's trick to improving highway fuel mileage........VCM engines are supposed to get about 2 mpg better on the highway but the lack of true VTEC also adds about 3/4's of a second to its 0-60 time.
I'd like to see some GenVIII 6-6 fuel efficiency notes............

My GenVII J30a4 6M gets highway numbers in the upper 30's most of the time using 87 octane, about 2200 RPM, sixth gear overdrive while in the desert, on the flat, maybe with a little tailwind.

The 08-11 6-6 should be able - if driven as above - to log mid 30's to my way of reasoning..........

all the best, ez....
 

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Ed, I have a local junkyard ready to sell me a ECM with matched keys from a 2009 base TL. they stand behind their products and have said if the ECM and keys are not a match they will pay to have it matched. As I said, cost to me isn't the issue, it's the fun of making something. I also forgot to mention three mounts would have to be changed since VCM will be removed. I figured selling most of these parts could help curb three cost some. And thanks for keeping this thread civil. :)
You will have to add IM and PS rack as TL is electric . you be surprised at how many small changes will be needed .
 

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I'd like to see some GenVIII 6-6 fuel efficiency notes............

My GenVII J30a4 6M gets highway numbers in the upper 30's most of the time using 87 octane, about 2200 RPM, sixth gear overdrive while in the desert, on the flat, maybe with a little tailwind.

The 08-11 6-6 should be able - if driven as above - to log mid 30's to my way of reasoning..........

all the best, ez....
Same thought here EZ. Unfortunately, fueleconomy.gov has very few entries for 2008+ model years. But here is what they do have:

2008 Coupe, manual tranny, non-VCM : 25.2 mpg based on 70% highway during the month of July.
2008 Coupe, automatic with VCM: 25.6 mpg based on 90% highway during the month of August.
2008 Coupe, automatic with VCM: 28.2 mpg based on 60% highway during the month of June.
2009 Coupe, automatic with VCM: 25.4 mpg based on 100% highway during the month of August.

In comparison, the 2006, 6-6 Accords reported 30.0, 25.2 and 31 mpg based on 90%, 85% and 80% highway driving respectively. It seems like the 3.0-liter is more fuel efficient. But based on the Gen8 real life stats, there does not seem to be any significant mpg difference between VCM and full VTEC engines. It makes me wonder.
 

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Discussion Starter #20
You will have to add IM and PS rack as TL is electric . you be surprised at how many small changes will be needed .

I had thought of the IM... thats what really got me thinking about this whole change.. It seems as if AT owners are hamstrung by VCM in at least moving up with changes to the engine..

I'll look into the PS rack.. I had never thought of that.. I'll see what I can find.
 
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