2018 cx5

[Red MC]

I haven't driven a car with cylinder deactivation. How long does it take to re-activate cylinders? If we are talking a few hundred milliseconds, then it may not affect acceleration enough to be noticeable. If it only comes into play when you are cruising at constant speed, and instantaneously reverts to 4 cylinders when you press the throttle, then it seems like all good assuming there aren't reliability problems.

If it decreases the maintenance interval for easy to replace spark plugs, that's a worthwhile trade-off. If it fouls sensors/controls and leads to ambiguous check engine codes, or premature engine failure - not good.

On the Hondas and Chevys, cylinder deactivation only kicks in at constant speed and light throttle. As soon as you press on the throttle it kicks out, and the transition feels pretty seamless to me. I've been told that if you listen carefully on a quiet road, you can hear a slight change in engine noise, but otherwise you probably won't notice it's working except by the dash indicator.

The main concern is oil fouling. You can change the plugs, but if there are deposits fouling the plugs, there are probably deposits in the combustion chamber as well. Honda also had problems with it wrecking engine mounts, but I think those have been solved.

 

[murky]

On the Hondas and Chevys, cylinder deactivation only kicks in at constant speed and light throttle. As soon as you press on the throttle it kicks out, and the transition feels pretty seamless to me. I've been told that if you listen carefully on a quiet road, you can hear a slight change in engine noise, but otherwise you probably won't notice it's working except by the dash indicator.

The main concern is oil fouling. You can change the plugs, but if there are deposits fouling the plugs, there are probably deposits in the combustion chamber as well. Honda also had problems with it wrecking engine mounts, but I think those have been solved.

Makes sense except the part about the engine mounts. How does that happen?

 

[Xeler8ing]

To everyone querying how it works, have a read of the opening post in this thread:

KF CX-5 with Cylinder Deactivation coming to EU

Here's a video also explaining it:

 

[Red MC]

Makes sense except the part about the engine mounts. How does that happen?

Let me correct/clarify what I wrote. Cylinder deactivation isn't destroying the engine mounts, the problem was that the engine mounts that were required to deal with cylinder deactivation were failure prone.

When Honda's VCM engages, three cylinders have to do the work of six, which means the torque pulses occur half as often but are twice as strong. The stronger torque pulses create stronger rocking vibration of the engine. To prevent owners from feeling this, Honda developed actively controlled engine mounts. The mounts have electrically controlled variable damping, which is modulated by the ECU based on crank angle position. By alternating the actuation of the front and rear engine mounts, the system creates a rocking force that counters the engine vibration. With the previous generation Odysseys that featured VCM, a fair number of owners had problems with the rear active engine mounts failing, which caused strong vibration. And because they have electrically controlled variable damping, the engine mounts aren't cheap: about $500 each.

Honda isn't the only one using active engine mounts. They are somewhat common these days, used to reduce engine vibration in vehicles with and without cylinder deactivation. The simplest forms just switch between soft/low damping and hard/high damping based on engine RPM, so they are very compliant at idle but firm up once you're underway. The more advanced forms produce a counter-vibrating force.

 

[dougal]

On the Hondas and Chevys, cylinder deactivation only kicks in at constant speed and light throttle. As soon as you press on the throttle it kicks out, and the transition feels pretty seamless to me. I've been told that if you listen carefully on a quiet road, you can hear a slight change in engine noise, but otherwise you probably won't notice it's working except by the dash indicator.

The main concern is oil fouling. You can change the plugs, but if there are deposits fouling the plugs, there are probably deposits in the combustion chamber as well. Honda also had problems with it wrecking engine mounts, but I think those have been solved.

On our odyssey we can feel the transition. It is a slight clunk that almost feels like a transmission clunk but it is the switch. Lots of discussion on the odyssey boards about this. Many people have developed methods to short-circuit the system.

 

[Red MC]

What year is your Odyssey? And have you had any problems with the VCM?

I didn't notice the transition on test drives of the Odyssey and Pilot, but obviously I wasn't intimately familiar like an owner would be.

 

[murky]

What year is your Odyssey? And have you had any problems with the VCM?

I didn't notice the transition on test drives of the Odyssey and Pilot, but obviously I wasn't intimately familiar like an owner would be.

Ah, makes sense.

I don't like the idea of added expense and sophistication on a wear part that is underneath the engine. I changed the motor mounts on my Acura, and that rear one was no fun at all.

 

[Xeler8ing]

Would be nice if the updated CX-5 got the new 7" TFT dashboard display from the new Mazda 6....

 

[dougal]

What year is your Odyssey? And have you had any problems with the VCM?

I didn't notice the transition on test drives of the Odyssey and Pilot, but obviously I wasn't intimately familiar like an owner would be.

We are in a 2015 Odyssey Touring Elite. Great van.