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Oddball engine question - if I understand the Ridgeline/Earth Dreams engine, it is 6 cylinders but can run with just 4 when less power is sufficient. Are there two "auxiliary" cylinders standing by, or can the engine dynamically rotate which 4 are used to distribute wear? Apologies for my naive understanding of how this works. I tried some searching and wasn't successful.

Thanks!
 

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It is a 6 or 3 configuration not a 6 or 4. The VCM shuts off one bank during low load conditions to conserve fuel. I honestly hardly notice it when I am driving. It seems like it occurs much more often when Econ is on. There have been some issues in the past especially from GM with uneven wear on crank bearings and in some cases even premature failure. I haven’t really heard much in the past few years and would assume most of these problems have been remedied. When VCM occurs the ECU changes a multitude of things to make transitions as smooth as possible these include, torque converter lock-up, throttle position on the DBW system, as well as ignition timing. The Ridgeline has a transverse mounted V-6 and therefore it is the rear 3 cylinders that disengage during VCM moments. The valves remain closed to reduce friction drag on the cylinders and the Ridgeline uses a unique set of hydraulic engine mounts that I think Honda calls “Active Control Engine Mounts” to cancel the vibration produced by an “unbalanced” rotational force. There is also a front and rear engine mount that produces a counter vibration to compliment engine vibration and overall making the resulting engine vibration nominal.

This was one of the biggest concerns when I bought my RL but have been overall satisfied and most of the time don’t even notice it’s happening.
 

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I don't notice it de-activating" but on my Corvette is is very noticeable and reads out on the dashand. It's been an issue for that motor and other GM vehicles. I never run the Vette in ECO mode to eliminate it going to 4 cylinder mode. I can do this because I have a manual transmission. The people with the Auto trans on the Vette cannot eliminate it unless they use paddle shifters. Its a problem there. The MPG difference is minimal anyway. The darn thing still can get 28-30 mpg on the highway if you can keep your speeds under 100 mph her

Best I've gotten in my new RTL-E is 24 highway ( 65-75 MPH) and 21 in mixed rural driving. Only 1600 miles on it so I'm hoping it goes a bit higher on the highway. I'm using the fill and calculate method most of the time and it seems that the computer err's to the high side about 1 mpg.
 

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@montanaman interesting about your vette, that basically just helps validate what I was saying about GM having trouble out of their previous models of VCM. Kind of surprised to hear that you have only managed 24 MPG on the highway, I live in KY which is somewhat mountainous where I live and gets very mountainous towards the east. My previous daily drive from Lexington to Louisville I would average 29.8 with Econ on and ACC set at 75 with A/C on set at 72 degrees. I used to have photos of my trip counter. It’s a 120 mile trip both ways so the data set is fairly vast. I know some people have mentioned the MPG calculator on the RL being about 1-2 MPG higher than what they actually get. On my 2019 I haven’t found this to be the case. Not sure if it is something they fixed in later models or not but my city MPG drops drastically to about 19-23. Lexington traffic can be atrocious during mid day so lots of stand still and with the way people drive I can’t afford to have Econ on dampening my throttle response. 😂
 

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Started with an 06 RL then to an 2017 which is when Honda installed VCM. After some research I installed a resistor in the water temp circuit which disables VCM. The jumper kit is available on EBAY, takes 5 minutes to install, no significant change in milage. Recently traded for a 2019 RL and transfered the kit from the 2017 to the 2019.
 

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It seems to me that my VCM is not noticeable in driving, however, keep an eye on your oil levels. During the times the rear cylinders are taking a nap, they are sucking oil up past the rings and into the combustion chamber. I'm using a quart every 4K miles and neither of my Gen1's used any at all.
 

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It seems to me that my VCM is not noticeable in driving, however, keep an eye on your oil levels. During the times the rear cylinders are taking a nap, they are sucking oil up past the rings and into the combustion chamber. I'm using a quart every 4K miles and neither of my Gen1's used any at all.
During three-cylinder mode, the valves remain closed so there should be no vacuum to "suck oil past the rings" - the cylinder is under pressure and acts as an air spring when the piston is above bottom dead center. Based on what I've read on this forum and my own experience with two, second-generation Ridgelines, I would consider one quart every 4,000 miles to be excessive and outside the norm - particularly if this is still occurring after the first several thousand miles while the engine is breaking in. My 2017 used just under a quart during its first 8,000 miles followed by no noticeable consumption up to 21,000 miles. My 2019 used about a half a quart during its first 8,000 miles.
 

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During three-cylinder mode, the valves remain closed so there should be no vacuum to "suck oil past the rings" - the cylinder is under pressure and acts as an air spring when the piston is above bottom dead center. Based on what I've read on this forum and my own experience with two, second-generation Ridgelines, I would consider one quart every 4,000 miles to be excessive and outside the norm - particularly if this is still occurring after the first several thousand miles while the engine is breaking in. My 2017 used just under a quart during its first 8,000 miles followed by no noticeable consumption up to 21,000 miles. My 2019 used about a half a quart during its first 8,000 miles.
Isn't Honda on record with a statement indicating oil consumption of 1 US Qt/1000 miles is considered 'normal'?

I agree with you that a quart every 4k miles is excessive unless an engine is starting to show its age.
 

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Isn't Honda on record with a statement indicating oil consumption of 1 US Qt/1000 miles is considered 'normal'?

I agree with you that a quart every 4k miles is excessive unless an engine is starting to show its age.
Honda says:

More than 1 quart every 1,000 miles - there's a problem
1 quart every 1,000 to 3,000 miles - there may be a problem
Less than 1 quart every 3,000 miles - there's no problem
 

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During three-cylinder mode, the valves remain closed so there should be no vacuum to "suck oil past the rings" - the cylinder is under pressure and acts as an air spring when the piston is above bottom dead center.
How do they do that? Is the DI version of the J35 (finally) equipped with hydraulic lifters that they cut oil flow to? Do they cut oil flow independently to each of the three (3 separate oiling circuits with 3 separate solenoids)?
 

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"The system is electronically controlled, and uses special integrated spool valves in the cylinder heads. Based on commands from the system's Electronic Control Unit, the spool valves selectively direct oil pressure to the rocker arms for specific cylinders. This oil pressure in turn drives synchronizing pistons that connect and disconnect the rocker arms." - 2017 Honda Ridgeline Press Kit - Powertrain

Even the 1981 Cadillac V4-6-8 system used solenoids to disconnect the rocker arms from the valves so that they remained closed to eliminate pumping losses. All modern engines with cylinder deactivation do this.
 

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And they can get the oil pressure to change fast enough to disconnect the rockers at exactly BDC of the intake stroke on each cylinder every time, eh? That's pretty cool, if it actually happens that way.
 

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And I still don't like VCM. ;)
 
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