Dangerous cylinder deactivation trouble on 2018 CX-5 and Mazda6 models

7eregrine said:
How? There's clearly an issue. I don't expect it to become an issue that effects every car like yrwie will surely assume. [emoji16]
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Am I missing something? There looks to be 1-2 people that might have an engine issue that does not appear to be a design flaw but rather a defective part. Engines fail and there are always going to be lemons. Predicting a car will fail for a specific reasoning once that appears yelling "HA" is not a logical argument for your cause.

I am not saying there is not an issue with CD, but so far, it does not look like that to me. I would also state that I am no fan of CD, which our Odyssey had, and see no purpose of putting it into a 2.5 let alone a 2.0 engine.
 
dougal said:
Am I missing something? There looks to be 1-2 people that might have an engine issue that does not appear to be a design flaw but rather a defective part. Engines fail and there are always going to be lemons. Predicting a car will fail for a specific reasoning once that appears yelling "HA" is not a logical argument for your cause.

I am not saying there is not an issue with CD, but so far, it does not look like that to me. I would also state that I am no fan of CD, which our Odyssey had, and see no purpose of putting it into a 2.5 let alone a 2.0 engine.
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I agree with your all of your analysis. Bad parts or bad assembly. And CD is a pointless complication for minimal benefit in this application.

But OP did mention 26 similar reports, IIR.
 
shadonoz said:
I agree with your all of your analysis. Bad parts or bad assembly. And CD is a pointless complication for minimal benefit in this application.

But OP did mention 26 similar reports, IIR.
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26 reported cases that's back in October last year.

IMO this problem is not caused by bad parts or bad assembly, but a bad design which purely relay on oil pressure which may have a wide range in real time to control cylinder deactivation. And you can't design an HLA which would make the rocker arm fall out from its location when the oil pressure is getting too low. Worse, there's nothing to detect the problem when the rocker arm dislodged and the intake valve is no longer functioning.

Go Hawks said:
Thanks for this info t.suv. So again I ask why is there no recall. My vehicle had this issue back in October of 2018. This bulletin is dated 4-8-19. And I know that my vehicle was number 19 that they knew of then. By the time I got my vehicle out of the shop they knew of 26 that had experienced this issue. Who knows how many now that have been reported? And who knows how many are out there with the issue but they haven't discovered it yet?
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yrwei52 said:
26 reported cases that's back in October last year.

IMO this problem is not caused by bad parts or bad assembly, but a bad design which purely relay on oil pressure which may have a wide range in real time to control cylinder deactivation. And you can't design an HLA which would make the rocker arm fall out from its location when the oil pressure is getting too low. Worse, there's nothing to detect the problem when the rocker arm dislodged and the intake valve is no longer functioning.
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Why are you sure that it is only the HLA retaining the rocker arm?
 
Huh, I wonder if the oil pressure is too low at certain conditions to de-activate CD, would it not also be too low to lubricate downsized crank shaft bearings at the same time during high-load operation... Extrapolating, but what if there is a possibility of cumulative excessive wear?...
 
shadonoz said:
Why are you sure that it is only the HLA retaining the rocker arm?
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Don't even think HLA is "retaining" the rocker arm. Rocker arm is floating with nothing to hold it. Once the HLA in cylinder deactivation phase dropped too low, the rocker arm is simply just falling out from the HLA side. The HLA designed for cylinder deactivation shouldn't get too low with low oil pressure. It's simply a bad design. At least Mazda should add something to "hold" the rocker arm in place all the time so that it won't be falling out because the HLA side is getting to low.

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yrwei52 said:
Don't even think HLA is "retaining" the rocker arm. Rocker arm is floating with nothing to hold it.
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Doesn't seem possible that they would design something so vulnerable to failure.
 
yugrus said:
Huh, I wonder if the oil pressure is too low at certain conditions to de-activate CD, would it not also be too low to lubricate downsized crank shaft bearings at the same time during high-load operation... Extrapolating, but what if there is a possibility of cumulative excessive wear?...
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I believe Mazda should have an independent control valve only to feed oil to these 4 HLA's used on intake valves of cylinder #1 and #4. They can't rely on variable-pressured main oil pump I hope?

I wonder what happened on those 4 valve trains with CD on the exhaust side for cylinder #1 and #4? I seemed to remember Mazda uses electrical relays to control the valve shut-off? Not sure.
 
shadonoz said:
Doesn't seem possible that they would design something so vulnerable to failure.
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Based on OP's description after he saw the picture, this's definitely the case, nothing to hold the rocker arm. That's why I called it earlier it's a genius design.

yrwei52 said:
Go Hawks said:
Its sounds strange, but the rocker arm is not attached to anyrhing in this engine. It is *pinched* between the cam and the lifter at one end and the valve stem at the other. Any slop on either end allows for the cam lobe to peel the rocker arm off and throw it down.
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Wow, there's nothing to hold rocker arms in place? What a genius design!
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So if I'm reading the original post correctly, Go Hawks experienced the limp mode problem 3 times under essentially the same circumstances each time, yet continued to drive the vehicle and re-enact the situation under the same conditions. If that had actually resulted in an accident any lawyer would have no problem proving that it was negligent behavior on the part of the driver. If there was concern that it was life-threatening then why continue to drive the car instead of having it towed to a Mazda dealer immediately?
 
dougal said:
Am I missing something? There looks to be 1-2 people that might have an engine issue that does not appear to be a design flaw but rather a defective part. Engines fail and there are always going to be lemons. Predicting a car will fail for a specific reasoning once that appears yelling "HA" is not a logical argument for your cause.

I am not saying there is not an issue with CD, but so far, it does not look like that to me. I would also state that I am no fan of CD, which our Odyssey had, and see no purpose of putting it into a 2.5 let alone a 2.0 engine.
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As other people have mentioned, there were 26 that the MOCO knew of back in October. Also, keep in mind, the percentage of CX-5 owners that are actually on this forum is very minuscule. So it may appear on here that the problem is minuscule. But, believe me if this happened to you, it becomes a huge problem. The big issue here is there is no way of knowing if or when your rocker arm fell off. Therefore we could have many people out there with this issue but haven't discovered it yet. They haven't had to raise the RPMs high enough to experience the limp mode activation. The car will run fine according to what the computer is sensing until the air fuel ratio isn't satisfactory resulting in the dangerous limp mode scenario. Also, as the driver you will not sense anything wrong such as a miss to indicate problems.
 
yrwei52 said:
Based on OP's description after he saw the picture, this's definitely the case, nothing to hold the rocker arm. That's why I called it earlier it's a genius design.
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That's actually nowhere near uncommon, many manufacturers use a similar rocker arm design. The oil pressure and valve spring pressure are usually quite sufficient to keep the rocker arm in place - in this case there's obviously something going on with the oil pressure that was unforeseen by Mazda. I wouldn't go anywhere near calling it a poor design since it's used successfully in most OHC engines on the road today.
 
RyanY said:
So if I'm reading the original post correctly, Go Hawks experienced the limp mode problem 3 times under essentially the same circumstances each time, yet continued to drive the vehicle and re-enact the situation under the same conditions. If that had actually resulted in an accident any lawyer would have no problem proving that it was negligent behavior on the part of the driver. If there was concern that it was life-threatening then why continue to drive the car instead of having it towed to a Mazda dealer immediately?
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I thought he did just that, which resulted in a camera re-program... Not sure how it helped dislodged rocker arm though.
 
Maybe it's time for all makers to reconsider limp mode. Maybe something a lot less extreme when a fault is found which could escalate if the problem persisted.

Limp mode protects the engine, but can put the occupants in danger.
 
yugrus said:
I thought he did just that, which resulted in a camera re-program... Not sure how it helped dislodged rocker arm though.
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Nope.

"We continued on our way with intentions of taking the vehicle to the shop once we got home from our vacation thinking that it may just be a glitch with the camera. We were wrong! This happened 2 more times on our trip before the incident that we will never forget."
 
shadonoz said:
Maybe it's time for all makers to reconsider limp mode. Maybe something a lot less extreme when a fault is found which could escalate if the problem persisted.

Limp mode protects the engine, but can put the occupants in danger.
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Ok, then let the oil be flooded with fuel and the cat killed in no time? That's in addition to severely less then expected power at WOT anyway? I'm not sure this is better solution.
 
RyanY said:
Nope.

"We continued on our way with intentions of taking the vehicle to the shop once we got home from our vacation thinking that it may just be a glitch with the camera. We were wrong! This happened 2 more times on our trip before the incident that we will never forget."
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I see. So that's what normally everyone does when they get a hiccup from the engine on the long trip. Just cancel everything and tow to the dealer. Spending a day or two there, depending. Well, not if the car runs fine on re-start, I don't think so.
 
RyanY said:
So if I'm reading the original post correctly, Go Hawks experienced the limp mode problem 3 times under essentially the same circumstances each time, yet continued to drive the vehicle and re-enact the situation under the same conditions. If that had actually resulted in an accident any lawyer would have no problem proving that it was negligent behavior on the part of the driver. If there was concern that it was life-threatening then why continue to drive the car instead of having it towed to a Mazda dealer immediately?
Click to expand...

Each time we experienced this we were basically in the middle of nowhere. One time on a two lane mountain road. One time on the freeway. And one time on a two lane highway. We were on vacation traveling from place to place. The first 2 times we were in broad daylight and all of our alarm indications made us believe that there was something wrong with the camera. It wasn't until the 3rd time that we were traveling in total darkness and nothing for the camera to see that we came to the conclusion that it was an engine issue and not the camera. Thats when we put all of our experiences together and realized that it had something to do with the higher RPMs. When we finally got to the shop (if you remember from my original post) all indications that they pulled from the computer were a camera problem too. I argued with them that it was an engine problem and had to take the car out and replicate the issue to prove it. I filmed the dash
as I sat on the side of the freeway and took that video back to the dealership to prove it to them. So even if I had taken it in after the first time, we all would have been in agreement that the issue was with the camera and still would have ended up in the same scenario. As far as lawyer is concerned, my wife and I have had many conversations about legal action. We think this could be big enough for a class action lawsuit. But, as you can see, even on this forum with the small sample of people here, it is almost impossible to make people believe this issue exists. Every step of this journey for me has been an argument. And all I am trying to do is make people aware that this DOES exist and it is EXTREMELY dangerous, particularly the way it presents itself to the driver.
 
shadonoz said:
Maybe it's time for all makers to reconsider limp mode. Maybe something a lot less extreme when a fault is found which could escalate if the problem persisted.

Limp mode protects the engine, but can put the occupants in danger.
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EXACTLY!! When my car did this the dash lit up and all kinds of audible alarms went off. That was more than enough to tell me something was wrong. Adding the limp mode into this accomplishes nothing except putting the driver in an awful situation. This is what i told the Mazda Western US technical rep when I talked with him. I told them they need to change that logic to protect the driver and not the engine.
 
shadonoz said:
I agree with your all of your analysis. Bad parts or bad assembly. And CD is a pointless complication for minimal benefit in this application.

But OP did mention 26 similar reports, IIR.
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So, let's assume there are 26 and that there are what, 200,000 Mazdas with CD out there? (Mazda 6 and CX-5), that is an issue on 0.013% of the cars. I don't think that is a huge number.

I would assume they have a much higher failure rate in other area's (like Miata transmissions!). And honestly, in a world were people like to communicate their problems (which is a good thing mind you), if this was a wide spread issue, I am guessing this would have shown up elsewhere (facebook).

Again, I don't know how big the issue is or not, it could be a very small issue on some cars and much less frequent than other issues or it could be the tip of the iceberg!
 
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