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Provisions such as CD and I-Stop are probably important to the manufacturer because they help to meet emission regulation tests rather than because they offer much benefit in real world driving. The ultimate example, of course, being the infamous VW firmware which recognised when the car was being tested and adjusted accordingly. If the engine can manage to negotiate much of an emissions test in CD mode the effect on its ratings would be significant.
 

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Provisions such as CD and I-Stop are probably important to the manufacturer because they help to meet emission regulation tests rather than because they offer much benefit in real world driving. The ultimate example, of course, being the infamous VW firmware which recognised when the car was being tested and adjusted accordingly. If the engine can manage to negotiate much of an emissions test in CD mode the effect on its ratings would be significant.
Yea I understand that part about emissions. That's the only reason it was in there. Obviously not important enough for them to take it out though

Another guy in the TSB thread has said he's definitely noticed a positive difference when he had the brackets changed. So I'll quit my bitching for now and have it done
 

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Could you go backwards if it was worse? Keep the old brackets of course... but would the old PCM programming still be available?
There will be no going backwards lol. The only thing going backwards will be my 2019 into the dealer parking lot for a 2021 in the fall if it doesn't work.

All jokes aside, I doubt they will let you go back to the old mounts and software

I've seen enough and contacted Mazda Canada with the TSB so they can give the dealer permission/find it. I'll have it done and follow up here.
 

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I took mine in this past week and they had to order other another part for the vibration tsb

I will be going back as soon as the part comes in and will update you guys
 

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Looking forward for your feedbacks.

By the way do you know if many things have to be dismantled to replace the radiator mounts? I'm always afraid when dealers have to disassemble something...
I don't think it is that invasive to be honest. They have the whole process including mounts and software listed at 0.4 of an hour. Probably just take the radiator cover off and then pop the mounts out, put the new ones in and then update the software

Not much to lose from trying this TSB.
 

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I was able to finally make some progress on the TSB - parts have been ordered and should have it completed in the next couple of weeks. Fingers crossed that after this, I can go back to praising the car instead of bitching lol
 

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It seems that Mazda is replacing the heads of 2.5 Skyactiv-G engines although as ASH8 says, this is not related to the TSB above or a Software change or Radiator Brackets, but more of engine tapping/knocking noise/vibration.

Vibration , cylinder deactivation issues

There is a service alert (not a TSB) regarding this new head part, for vehicles with CD only.

Link
 

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It seems that Mazda is replacing the heads of 2.5 Skyactiv-G engines although as ASH8 says, this is not related to the TSB above or a Software change or Radiator Brackets, but more of engine tapping/knocking noise/vibration.

Vibration , cylinder deactivation issues

There is a service alert (not a TSB) regarding this new head part, for vehicles with CD only.

Link
A little confused on this one. Is this issue being caused by the CD system?

It does appear to only be available for cars with CD. How do they define "When needed"? Is it a check engine light, is there damage being caused?Do you find out by breaking down on the side of the road lol?

That is certainly interesting, that is for sure....
 

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I could be wrong here but when CD first came out there was a PCM related issue where, when CD was actuated, it was at the wrong part of the 4-stroke cycle (and likewise when CD was switched off...) - and the rocker-roller cam followers ("rocker arms") displaced out of their intended locations... b*ggering-up the cylinder head. Does this address previously unknown to be damaged cylinder heads?
 

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I could be wrong here but when CD first came out there was a PCM related issue where, when CD was actuated, it was at the wrong part of the 4-stroke cycle (and likewise when CD was switched off...) - and the rocker-roller cam followers ("rocker arms") displaced out of their intended locations... b*ggering-up the cylinder head. Does this address previously unknown to be damaged cylinder heads?
Could be. If you are interested in reading a novel about when the issue was discovered in the 2018 CX-5 you can look at this post from Mazdas247. I do believe it could have been people in that forum that got the ball rolling with regards to letting Mazda know about it.

 

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Class action. For a few mpg cylinder deactivation destroys the engine. Left over un burned fuel rinses the oil of the cylinder walls and mixes with the oil. Unbalancing an engine cycle is NEVER a good thing.
 

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This is the service alert.
Does not seem to be related to a recall.
Any one can clarify?????
Nobody know much about it.
Class action. For a few mpg cylinder deactivation destroys the engine. Left over un burned fuel rinses the oil of the cylinder walls and mixes with the oil. Unbalancing an engine cycle is NEVER a good thing.
Well I think it will dependent upon how Mazda handles things. I still like Mazda and these issues are really out of character for them.
I think they made the right call pulling it out of the 2021 lineup. Unfortunately leaves some people in a lurch that bought one(those with issues)

And yes I know there's tons of people that haven't had an issue with it, but that doesn't mean down the road they won't. Do I think the 2.5 skyactiv G with CD will stack up the same as the old school Skyactiv G in terms of reliability? Probably not

And you are right, the difference in fuel saving is so negligible on a 4 cylinder that it doesn't seem worth it.
 

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Sorry ... complete non-technical/idiot here, but it strikes me that all of this (from Mazda) is 'closing barn door after horse has bolted'.

If the cylinder-deactivation thingy is a matter of computer module programming, why could not Mazda offer a control module update that removes cylinder deactivation -- for those who choose to do so?

Ours ('19 3 GT, Cdn spec) has never been problematic, and we've had the 'rocker arm concern' recall done, but nevertheless, it seems odd to me that owners couldn't be given the option simply to have this bit of programming removed from their cars. Is there something different about the construction of the motor that makes this a non-starter?

If not, I for one would certainly go for such a solution.
 

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I suspect that as the car was emissions certified with CD and its fuel consumption was represented to the authorities as havng CD (i.e. fuel consumption relates to CO2 emissions)... Mazda cannot remove it... but they could make CD the default arrangement, with CD disabling a menu option each time the car is started.
 

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I suspect that as the car was emissions certified with CD and its fuel consumption was represented to the authorities as havng CD (i.e. fuel consumption relates to CO2 emissions)... Mazda cannot remove it... but they could make CD the default arrangement, with CD disabling a menu option each time the car is started.
This is exactly it. They will not shut it off permanently. But yes, a menu option to shut it off would work. Even if it was defaulted to on and you had to do it each time you turn the car. I could leave it on in town to save gas (as below 90kmh you can't tell its there) and then turn it off when it becomes problematic(between 90kmh and 100kmh)

Most car companies that offer it have the ability or button to turn it off. I still to this day hold my ground that it worked fine the day I bought it and at about 10,000 km for some reason the vibration appeared. Pre covid I drove about 63 km one way to work in it and I was excited each time I got to go to work before the vibration showed. Mine is an early production model, so it's possible they noticed something and changed some things mid production, who knows.
 

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2021 Mazda3 specs are now listed in Canada and there is no mention of cylinder deactivation. It looks like city gas mileage is slightly worse.
 
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