This video should help.

 

This video should help.

https://youtu.be/iJIVsXPrENc

I’ve seen it. What I want to know is how the system works in the Honda compared to this


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Nice video. I wonder how much fuel is saved with this system and whether it impacts the long term reliability of the engine?

 

I heard a while back that you get about 1 mile more to the gallon with this system. Reliability, who knows.

 

I’m curious to know if Mazda has been able to engineer out some of the drawbacks of using cylinder deactivation. In the Honda forums they complain about fouled plugs and oil consumption problems. According to the cute little video from Mazda they are using a different type of mechanism to engage and disengage the valves. I just really want to understand Mazda system versus Honda’s system and I’d like to extrapolate whether or not it will in the long run be reliable compared to the Honda system.


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In Europe, Ford sells two engines in 3 cylinders: 1l EcoBoost and 1.5l EcoBoost.
The 3 cylinders engines, have turbo of course, high pressure direct injection and cylinder deactivation.

If you are worried about reliability of a 2.5NA engine which was out for a couple of years and was put into almost everything that Mazda has (3, 6, CX-5) and it's just a higher scale of 2l engine, how would you feel about a 3 cylinder 1l EcoBoost with cylinder deactivation on a Ford Focus?

I do not want to take the the discussion sidewise but the 1l EcoBoost is very popular, won the "Engine of the year" several times and it kinda proved it's reliability; having a technology, if engineered properly, can be reliable.

Honda made it's first small direct injection 1.5l turbo engine (the one in the Civic and CR-V) and kinda blew it up with oil dilution.

 

I will have to take your word for it about the Ford reliability. Personally I’ve never had good luck with Ford and I don’t think they are all that reliable. I just traded a 2017 Honda Civic hatchback with a 1.5 L turbo engine in question. I knew about the oil dilution problem before trading it but I never experienced any issues with the engine. Shortly after I traded the car I got notice from Honda that they have extended the warranty by another year on the engine with unlimited mileage.

I leased this vehicle for three years so I’m not overly concerned about reliability. I can just get rid of the car when the time comes unless I choose to buy it out right at the end of the lease. I’m just more curious about the engineering solutions that Mazda has come up with


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Part of the challenge with cylinder deactivation is engineering a method to control engine vibrations. Honda VCM used electronically controlled engine mounts to dampen vibrations. I believe Mazda is using a device/mechanism in the transmission.

I know some Honda owners still complained about vibrations and I'm not sure Mazda's solution is better or worst but I can definitely still feel the vibrations when the cylinder deactivation kicks in.

 

With my car I can feel the very slightest of a hiccup if you will when cylinder deactivation cuts in but there is absolutely no vibration. This is one of the smoothest drivetrains of any car I’ve ever owned


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I hope Mazda has moved on from Cylinder Deactivation by the time I upgrade my vehicle as I would never buy a car with this "feature". The good news is that SkyActiv-X doesn't employ Cylinder Deactivation so it looks like Cylinder Deactivation will only be an interim solution.

 

At first I was disappointed that we didn’t get Skyactiv X this year but now I’m glad. Let Europe be the Guinea pigs on this engine. It’s a new technology and will undoubtedly have its issues too


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Are you sure Skyactiv-X doesn't have cylinder deactivation?

I think the answer Mazda must give is to rollout a software update that lets the user decide to enable or disable the feature. Or eventually somebody will break into the software mapping.

 

Are you sure Skyactiv-X doesn't have cylinder deactivation?

You can see it at the bottom of page 15 in the PDF of the post below

https://mazda3revolution.com/forums/2460171-post22.html

 

Any idea why cars with Cylinder deactivation have more oil in the gearbox?

 

The transmission for 2019 is a bit different from previous years. Most likely the extra fluid has something to do with the vibration dampening mechanism... Or not.....:dunno:

 

If it were up to me, (its not), I would not add the complexity of cylinder deactivation to gain one mile per gallon. Not worth it. But, I have it now, and I 'll have to live with it. It already failed once, and caused this brand spanking new 3 to spend a month in the shop waiting for parts from Japan. Its fixed now, and so far the car is running great. We'll see.

 

What happed when it failed? Did it stop running completely and we’re you driving when it happened?


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The car went into limp mode intermittently. Yes, while driving. I could get where I was going, at about 25% power or so. The dealer explained it by telling me that there is a part incorporated in a section of the exhaust that varies the back pressure provided by the exhaust depending on whether the engine is running on 2, or 4, cylinders. That part was not working properly. The system sensed the wrong back-pressure and put the engine in limp mode to protect it from damage.

 

At least it wasn’t an internal valve mechanism that could have damaged the engine.


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I still have not understand. Is some people getting a physical part replaced in the exhaust? Others just a software update? Are we talking about the same recall or 2 different ones?

 

The software update is the recall. The exhaust valve part is not. At least I have not seen a recall for the exhaust valve.


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As far as I know, the problem I had (required replacement of an exhaust part that varies back pressure) is not the subject of a recall. I have not heard of anyone else with this same problem.

EDIT: Someone above referenced exhaust VALVE. My problem had nothing to do with exhaust VALVES.

 

As far as I know, the problem I had (required replacement of an exhaust part that varies back pressure) is not the subject of a recall. I have not heard of anyone else with this same problem.

There is nothing in the exhaust system that regulates back pressure. :dunno:
I think what you are referring to is a shutter that blocks off the part of the exhaust that isn't used when the cylinders are de-activated. This keeps the exhaust flow normal and prevents reversion pulses from traveling up and down those unused pipes, something that can cause a bunch of problems for the cylinders that are still running. If that shutter is not opening when it should the engine won't run right if at all....

 

When the cylinders are shut off only two of the four primary exhaust pipes (#1 through 4 in the CS diagram) are used because there is no ignition in those cylinders. (cylinder 1 and cylinder 4 get shut off)
Because there is no ignition there is no exhaust pulse traveling through those two pipes. Those unused pipes create what is virtually an empty chamber, and exhaust pulses from the active cylinders will travel up them then echo back into the exhaust stream, causing a reversion-type obstruction to the flow from the active cylinders. If those two pipes are closed off at the collector where the flow from all four pipes enter the exhaust system, the flow from the two active cylinders will be normal. I assume that the shutter assembly the tech referred to would be placed somewhere between the primary collector and secondary collector where the flow from cylinder 1 and 4 enter the main exhaust stream. Since exhaust gas velocity is critical to the operation of the SkyActiv engine, anything that restricts the flow will reduce gas extraction from the cylinder, causing cylinder temperatures to go up and leaving residual unspent fuel in the chamber. This causes knock or pinging, which, when detected by the knock sensors, causes the ECU to pull engine timing until the knock is gone.

 

Interesting. Isn't the exhaust stroke just pushing "clean" air instead of burnt exhaust gases at exactly the same velocity that it does when there is normal ignition?

Seems like back pressure is part of what you are describing, no?

I gotta say, it all seems terribly complex for a very small gain in fuel economy. Lots of stuff to break.

 

No, if you watch the video demonstration you can see that the valves don't open when the cylinder is de-activated, so there is nothing being pushed out and the two primary pipes are just dead space.
As for the back pressure, sort of but not not really. The exhaust system is designed to provide maximum scavenging. Basically the timing between pulses exiting the exhaust creates a vacuum that draws the hot gasses out. The empty pipes can create a reversion wave that will disrupt the scavenging and make the exhaust less efficient.
Yes, it does seem like a lot of work went into making a simple thing into a Rube Goldberg device. Lots to go unnecessarily wrong for very little return.

 

can't wait for the X>