By the way, I'm not sure I understand what do you mean by this:
... hydraulic lash adjuster that deactivates the compression in the cylinder.
It shows in the second pdf that the lash adjuster can be shortened by oil pressure so that the valves remain closed. This leaves the piston reciprocating without fuel or ignition. The residual compression and depression balance themselves out and almost eliminates the “pumping losses” that would otherwise work against efficiency.
It seems that it’s as simple as letting cylinders 1 and 4 run light.
The system detects constant (steady) light load demand and then seamlessly shuts down the outer 2 cylinders. If the demand changes, the system immediately brings in the 2 cylinders back in - again, seamlessly. In the above youtube clip, Thomas says he can’t detect it operating in the absence of a light that some vehicles have.
Other than the particulars of how they disable value operation, it looks like every other cylinder deactivation system to me. What's different?
I’m not familiar with other brands but there is only one other 4 cylinder version on a 1.4 Mitsubishi engine which has the reputation of being utterly reliable.
I agree with both of you and we still haven't seen anything special from Mazda to prevent common issues from cylinder deactivation. This makes me worried for Mazda a few years later when CX-5 owners are running into the exact same problems like every other vehicles with cylinder deactivation! Mazda may program its system activated less frequently with very short cycle, but this’s a 4 cylinder which could make the common symptoms showing up faster than those V6’s and V8’s!
Once you get a bee in your bonnet it seems like no amount of reassurance will convince you and you are not prepared to be open minded. I can tell you that after 5 years of oil consumption issues with 2.2 diesels, this newer version in my 2017 model is completely cured. What has changed? Well they’ve changed the design of the pistons and rings and they’ve changed the mapping of the DPF regeneration to give much shorter periods of post injection. So! After years of dilution problems, they’ve found a solution. In getting up 9000 miles the oil has not budged (unless of course there is an astonishing match of consumption and dilution but unlike the 2016.5 model the oil doesn’t stink of diesel). There are many other manufacturers still suffering with dilution and it appears to me that Mazda have fixed it. I’m not sure what the “many issues” with CD are but with the current success with piston rings is anything to go by, it shouldn’t be associated with that. Add to that newer high tech oils and greater accuracy of engine management systems, why shouldn’t it work? My diesel completely shuts of diesel on over run to conserve fuel so if I was to coast down a several mile descent, those cylinders would be completely starved of fuel. BTW, I’d very interested in the comments from anyone who can compare before and after the 2017 model oil dilution on the 2.5 Skyactive G.
I would think the opposite would be true.
The only place the cylinder deactivation will actually get used is on the EPA test cycle.
Nope, the system detects constant light load conditions and will work its long as the vehicle is operated. I doubt Mazda would risk any VW shenanigans!
LOL!
But only gets 1 mpg gain on FWD and 0 mpg gain for AWD? Mazda’s programmers need to learn something from VW’s engineers!
This fixation with fuel consumption in the US bewilders me. Its even added to the sales bumf just to keep you happy. Engine development is driven by legislation and the overwhelming driving force is the reduction in harmful emissions. True, there is a modest improvement in fuel consumption but just like a 6 cylinder engine has and exponential improvement in
emissions over an 8 cylinder and a 3 cylinder engine has the same improvement over a 4 cylinder engine, a 2 cylinder engine, even if only temporarily, gives a monumental improvement over the same engine running on 4 cylinders - it makes a big difference to the average. When vehicle manufacturers meet with legislators, they have to present plans of how they intend improving emissions to work towards the next mile post. They also have to produce plans for recyclability - the further impact on the environment. Its currently held back by current US policy but even Mr Trump had a softer approach in his recent European meetings. However, the technology and the benefits crossover and CD has been available in Europe for some time, its only new to you. I honestly wish I could get my hands on one but they don’t sell the 2.5G here.
From the owner's manuals I noticed that the Automatic Transaxle Fluid capacity has changed between 17 & 18 MY.
2018: 8.0 L (8.5 US qt, 7.0 Imp qt)
2017: 7.8 L (8.2 US qt, 6.9 Imp qt)
Is this change due to CD? If so is it because the cylinders (with CD feature) are actually larger requiring more lubricant? Or is it just a new preventative guideline to refill with more lubricant hopefully to avoid all those potential problems with CD?
Its a good question and the answer is, probably. In this article on CD there is the only reference I can find to the transmission being equipped to combat potential vibration issues that used to be associated with CD. Again I quote Thomas who says the vehicle is very smooth and very quiet. I have trawled the Mazda tech website and can’t find out what the “fulcrum” consists of but without knowing what it consists of, I might be looking in the wrong place and trust me there are 1000s of pages. Maybe I’m thinking too hard about something that was already there and just serves to dampen vibration.
https://insidemazda.mazdausa.com/the-mazda-way/technology/mazdas-new-cylinder-deactivation/