I'll be in the market for a new SUV towards the latter half of this year, and the MDX naturally fits the bill. The only remaining item preventing me from making the final decision is VCM. I kept hearing mixed reviews of this technology. Most of the complaints came from Honda owners with issues such as fouled plugs, high oil consumption, vibration, and premature engine mount wear. On the other hand, many Acura owners praised the technology and claim to be getting close to 30 mpg on the freeway and VCM transition seems to be seamless.

My concern is long term reliability. VCM always disables the same bank of cylinders so in the long run what adverse impact will this have on the engine? Several questions:

1. Is the VCM technology any different between Honda and Acura?
2. For high mileage 3rd gen MDX owners, how is the engine holding up? Any oil consumption issues? Any vibrations?
3. Has anyone changed the spark plugs on their 3rd gen MDX yet? Any issues with fouled plugs?
4. Open ended question: Why is Honda/Acura using VCM, but Toyota/Lexus decided not to?

 

My 19 Hybrid has VCM; but, I've never noticed it engaging or disengage. I've taken several road trips for about 8000 miles total. Not sure if the VCM will work at speeds my normal cruising speeds of 75-80 mph?

 

AFAIK the hybrid does not have VCM, only the regular one. And no you cannot feel it activating, all issues in the regular MDX arise from the ZF****d 9 ways transmission, fine vehicle apart from that.

 

Are you sure about this? It's listed as a feature for Hybrid MDX on the Acura website:
https://www.acura.com/performance/mo...der-management

 

Acura needs to update its website on VCM. It states VCM is used with the 3.5L and 3.0L hybrid motors. https://www.acura.com/performance/mo...der-management

No mention of VCM in the MDX sport hybrid owner's manual?

 

Sales-speak on the link below . . . . . . but a good explanation of what is supposed to be happening with VCM. Now I'd like to find some info on what vehicles actually have this feature. Not doubting undertaker2k8, but I was told the hybrids do have VCM.

https://www.jaywolfeacura.com/variab...nagement-acura

 

But this says nothing about a hybrid . . . .

https://www.acura.com/mdx/modals/35-...t-injection-v6

 

I've noticed Acura does have a bad habit with incomplete info on their websites and manuals.

 

It is very unclear if the 2019 Hybrid has VCM. The window sticker clearly indicates that it does have the feature. However at techinfo.honda.com There was an article that explicitly said that the 2019 MDX Hybrid does not have VCM. Unfortunately I cannot find it to post it.

 

Very interesting. So now the million dollar question is: Which year MDX Hybrid does not have VCM?

Regardless of how seamless the VCM transition is, it always bothers me thinking that at certain times I'm only operating on 3 cylinders, and it's always the same 3 cylinders which will eventually cause uneven wear in the engine. Even Acura sale-speak acknowledges that sometimes vibration can be felt and this is completely normal. Acura tries to address the vibration issue by designing an electronically controlled, fluid-filled engine mounts. But this begs the question: Is saving 1-2mpg really worth the trouble? Maybe on Honda vehicles it makes more sense, but on a $50K+ luxury vehicle it just doesn't feel right. Of course, everything said is just based on my personal opinion.

If we can confirm what year Hybrid model does not have VCM, I'd go out and buy it in a heartbeat.

 

Most of my MDX usage is Interstate driving, so the VCM usage is minimal. If you intend to drive a lot in slower traffic, you might want to consider the VCM Muzzler that shuts the VCM system off.

 

Maybe the MDX Hybrid has VCM; but, it doesn't engage as frequent as the 3.5L engine? I've taken road trips in my 18 RLX hybrid and really haven't notice or felt VCM engagement in that vehicle also (same speeds of 75-80 mph). Does the 3.5L engine in VCM still show the same rpms in 3 cylinder mode as it does in 6 cylinder mode?

The only two time I seen anything close to VCM is when the hybrid moves into EV mode like:
- on level ground under 50 mph with the engine off and the electric motors adding a little boost, or
- the hybrid is on a decline and the engine and electric motor shut off completely with speeds up to 65 mph.

Not sure if the OP is considering the Hybrid or just the 3.5L only. The Hybrid with the 3.0L port injection might reduce/eliminate all of your concerns.

 

Lexus is using cylinder deactivation on the RC- models starting in 2015.

 

The RC-F engine uses Atkinson cycle at cruise speeds and switch to Otto cycle for all other driving conditions, but I'm pretty sure it doesn't deactivate any cylinders.

 

I think you may be over-analyzing this situation. Early Honda implementations of VCM was more problematic, especially in the Pilots second generation. That's when the VCM Muzzler product was created. But that being said, having owned several post-2012 Acuras within our family, I can say that the VCM implementation has been vastly improved. to the point I don't even remember noticing it engaging in any of them ('13 MDX, '12 TL, '17 MDX, '19 MDX, '18 RLX Sport Hybrid). I wouldn't make the existence of VCM be the one thing that stops you from investing in it....

andy

 

I had a 2013 RDX and you could feel the shake from VCM in the steering wheel along with a rumbling sound.Mid display mileage level would show about 40 mpg. All notceable at 29,39,49.59 miles per hour.
I bought a 2018 MDX Advance with 12,000 miles. I have listened and tried to distinguish VCM.The only thing I notice is the Mid display shows better mpg.No noise no vibration,nothing. I now have 21,000 miles.

 

My wife had a 2017 RDX and it was impossible to perceive the cylinder deactivation or activation.

 

Thanks guys for all the inputs. Sounds like Acura has refined the VCM technology over the years and the transition is now seamless, at least on the MDX. Still wished there is an option to turn it off. Also wished there is a vehicle setting that can default auto start/stop to off. Maybe I just need to stop worrying and buy the vehicle.

 

Changed plugs at 88000. No sign of fouling.

 

Probably no way to tell if DI has fouled the intake valves? Wondering if the Acura 3.5L DI engines would benefit from an oil catch can or not.

 

My new plugs are ruthenium NGK ...200,000 mile plugs...burn stronger. Don't know if they would lessen fouling chances but mere logic says probably. The intake probably not affected however. Wouldn't a PEA fuel additive help that.