Dangerous cylinder deactivation trouble on 2018 CX-5 and 6 models

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2018 CX-5 Sport
Bozmanx, the only symptom that the guys had who had a thrown rocker was the car going into limp mode once in a while. It is a long read, but start from the first post. In the beginning there was little understanding of the issue. This is one of the pictures with the rocker out of place:

IN5SX12 (2).jpg
 
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184789

Bozmanx, the only symptom that the guys had who had a thrown rocker was the car going into limp mode once in a while. It is a long read, but start from the first post. In the beginning there was little understanding of the issue. This is one of the pictures with the rocker out of place:

View attachment 295696
Hey , as I said Im not doubting what you are saying, but that cylinder would be down on compression and always laboring you would have rough idle and average power. No one has said that they had any other issues except for the limp mode activation. Maybe you all missed that the idle was bad and power was not as good as it used to be? Its basic mechanics, a cylinder that is not able to draw in as much air as the others will create rough ide and poor performance. The engine relayes on every cylinder action the same for smooth idle and good power. When one of those cylinder is basically miss firing or only half charging its going to be noticeable.
 
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2020 CX-5 AWD
Hey , as I said Im not doubting what you are saying, but that cylinder would be down on compression and always laboring you would have rough idle and average power. No one has said that they had any other issues except for the limp mode activation. Maybe you all missed that the idle was bad and power was not as good as it used to be?....
Sorry but what you wrote there makes no sense to me at all. 'Always laboring, rough idle, and average power' is not going to be missed by any driver except a totally oblivious one. And that collection of conditions is never going to be missed by the ECM, which would set a misfire code in short order. Not going to argue this with you any further however, because it's all just subjective speculation, and cannot be supported by hard facts.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Hey , as I said Im not doubting what you are saying, but that cylinder would be down on compression and always laboring you would have rough idle and average power. No one has said that they had any other issues except for the limp mode activation. Maybe you all missed that the idle was bad and power was not as good as it used to be? Its basic mechanics, a cylinder that is not able to draw in as much air as the others will create rough ide and poor performance. The engine relayes on every cylinder action the same for smooth idle and good power. When one of those cylinder is basically miss firing or only half charging its going to be noticeable.
I agree with edmaz here. Based on those experienced the fallen rocker arm, especially the OP Go Hawks who almost involved an accident while passing, there’s not any symptoms including misfire CEL until you go for very high rpm and the engine falls into the limp mode. There’re other victims also said the same thing, which made them hard to get any dealer service until the whole thing exposed by the effort of those such as Go Hawks. Apparently one intake valve instead of two is sufficient enough to make regular engine operation in low rpm’s smoothly without triggering any CELs.
 
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184789

I agree with edmaz here. Based on those experienced the fallen rocker arm, especially the OP Go Hawks who almost involved an accident while passing, there’s not any symptoms including misfire CEL until you go for very high rpm and the engine falls into the limp mode. There’re other victims also said the same thing, which made them hard to get any dealer service until the whole thing exposed by the effort of those such as Go Hawks. Apparently one intake valve instead of two is sufficient enough to make regular engine operation in low rpm’s smoothly without triggering any CELs.
I'm sorry but the values are not for redundancy, a value not opening (even when there are two) will have an effect on performance. Drivers tend to have a pattern to there driving, those who over take generally overtake and with the WOT. Its not a one off, what happened the other times they when WOT ? Im not saying that the rocker did not come off, I saying that there would have been other symptoms.
 
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184789

Sorry but what you wrote there makes no sense to me at all. 'Always laboring, rough idle, and average power' is not going to be missed by any driver except a totally oblivious one. And that collection of conditions is never going to be missed by the ECM, which would set a misfire code in short order. Not going to argue this with you any further however, because it's all just subjective speculation, and cannot be supported by hard facts.
wow , sorry that factual information is so offensive to you, the facts are straight forward , an engine with two inlets valves does not have them for redundancy, they are for capacity. The inability of cylinder 4 to draw in as much air as the other cylinders would have meant that it was not producing as much power as the other cylinders. This will cause the symptoms that I described. This is basic knowledge for a combustion engine. Its not a misfire so wont register as one in the ECM.

It would appear to have been a mistake for me to register at this site as people are clearly not willing to listen to others options even when they are licensed in that field.
 

sm1ke

Work In Progress..
Moderator
Contributor
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Canada
:
'18 CX-9 Signature
wow , sorry that factual information is so offensive to you, the facts are straight forward , an engine with two inlets valves does not have them for redundancy, they are for capacity. The inability of cylinder 4 to draw in as much air as the other cylinders would have meant that it was not producing as much power as the other cylinders. This will cause the symptoms that I described. This is basic knowledge for a combustion engine. Its not a misfire so wont register as one in the ECM.

It would appear to have been a mistake for me to register at this site as people are clearly not willing to listen to others options even when they are licensed in that field.

I don't see where anyone is taking offense. Up until this point (your post) it seemed like a well-mannered discussion.

Prior to this post, there was no indication that you are licensed in this field, or that you have any credentials that might reinforce the validity of the information you are providing. Even if you say that you are licensed in this field, nobody has any way of proving it without more information about you. Please do not take offense to this - it is just a matter of fact. If there is information that you think others can benefit from, feel free to provide it, as it gives others the chance to learn. If someone disagrees with you, you can choose not to continue the conversation with that person.

This is a good opportunity to remind everyone that we are all here for the same purpose and that we share a common interest. To quote one of our forum Guidelines (found here):

III. Guidelines​

  • d ) Be respectful of others at all times. The purpose of Mazdas247 is to provide a platform for the exchange of ideas. Occasionally, there will be conflicts that arise when people voice opinions. Be courteous when disagreeing with others. It is possible to disagree without being insulting.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I'm sorry but the values are not for redundancy, a value not opening (even when there are two) will have an effect on performance. Drivers tend to have a pattern to there driving, those who over take generally overtake and with the WOT. Its not a one off, what happened the other times they when WOT ? Im not saying that the rocker did not come off, I saying that there would have been other symptoms.
Honestly most of us were stunned when OP described his experience at beginning, especially with no symptoms with a fallen rocker arm on cylinder #4 until he was trying to pass with full throttle. If you read the entire thread, and other threads at the same time for the same issue, you should know where are edmas and I coming from. We said that based on people’s actual experience, not based on theory. Yes you should be able to tell a rocker arm has fallen with some sophisticated equipment, but not from most drivers.
 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
For years engines operated with one intake and one exhaust valve per cylinder effectively but at lower rpms and many still do. At high rpms there is less time for the air to move and thus the design with multiple valves so as to get high power with high rpms out of smaller lighter engines even though it is less efficient. Highly efficient engines turn over slower and most are 2 valves per cylinder. My experience is that less than 3000 rpms with less than heavy load on a CX-5 it is difficult to detect one intake valve not opening, now if it did not close that would be a different matter.
 
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2018 CX-5 Sport
184789 I thought the exact same thing. I thought if I was driving and suddenly the rocker came off and shot to the corner of the upper end and then an intake valve stayed closed that I would imediately hear and feel it. But two members on this board described their symtems and neither noticed anything irregular except when accelerating in high rpms when their cars went into limp mode. I even questioned GoHawk's account because his car went into limp mode, he turned his car off and back on, and then drove like a maniac to pass a truck that was going too slow for him :). If my car went into limp mode I would stop and call Mazda to see if I needed to be towed in.
 
No, not literally a minute. Just a few seconds, Maybe between 5-15 seconds. Remember, all you are trying to do is see if the computer senses a *misfire* on a cylinder due to the air/fuel ratio not being correct. So it may sense it as soon as you get above 5500 rpms or it may take it a few seconds to sense it. Mine happened when I was passing a vehicle. I was accelerating and keeping the RPMs high when it would go to limp mode.
Could this be done in neutral or does it need the load?
 
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2020 CX-5 AWD
Could this be done in neutral or does it need the load?
What you're really asking is if the limp mode could happen if the engine was revved way up in P/N. It's an interesting question, which I don't recall having been discussed here previously. And IMO it would be virtually impossible to give a definitive yes or no answer without testing it out. And that would probably mean on a vehicle that's known to have a rocker arm detached, or by some remarkable coincidence flushed one out. Perhaps we can find someone who would like to be able to test this out ;)
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Could this be done in neutral or does it need the load?
IMO the engine needs load to trigger the limp mode, at least it should be easier to happen, if a rocker arm has fallen. You use the manual mode and down-shift to the 4th or 3rd gear with 5,000+ rpm for 15 seconds while you’re driving on the highway when the traffic is light. This should be pretty safe and easy to do.
 
I can
What you're really asking is if the limp mode could happen if the engine was revved way up in P/N. It's an interesting question, which I don't recall having been discussed here previously. And IMO it would be virtually impossible to give a definitive yes or no answer without testing it out. And that would probably mean on a vehicle that's known to have a rocker arm detached, or by some remarkable coincidence flushed one out. Perhaps we can find someone who would like to be able to test this o

IMO the engine needs load to trigger the limp mode, at least it should be easier to happen, if a rocker arm has fallen. You use the manual mode and down-shift to the 4th or 3rd gear with 5,000+ rpm for 15 seconds while you’re driving on the highway when the traffic is light. This should be pretty safe and easy to do.
Want this destroy the transmission?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I can



Want this destroy the transmission?
No, it won’t. Actually nothing will put any pressure to the transmission, but the engine is. You’re only adding pressure to the engine with high rpm. With warm engine and enough oil, your engine will be perfectly fine by revving it to the red line (6,000 rpm).
 
No, it won’t. Actually nothing will put any pressure to the transmission, but the engine is. You’re only adding pressure to the engine with high rpm. With warm engine and enough oil, your engine will be perfectly fine by revving it to the red line (6,000 rpm).
I thought you meant fly down the highway at 60 and downshift to get that rpm. Or do you mean just keep it in same 3rd or 4th gear to get the 5000?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I thought you meant fly down the highway at 60 and downshift to get that rpm. Or do you mean just keep it in same 3rd or 4th gear to get the 5000?
I’d say either way will do depending the highway speed and traffic condition at the time. Use manual shift starting at the 3rd or 4th gear going up the rpm you want on the highway may have better control.
 

trevorjk

2018 CX5 GT AWD, Vancouver, Canada
From reading the first 10 and last 20 pages on this post... looks like there is no way to tell whether the rocker arm has been displaced other than to remove the valve cover or use a endoscope?

I'm looking into purchasing a used 2018 GT. I have the service records and I can see that the PCM was updated as per the recall at ~14,000 km. Hoping that the rocker arm did not become displaced during that driving period...
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
From reading the first 10 and last 20 pages on this post... looks like there is no way to tell whether the rocker arm has been displaced other than to remove the valve cover or use a endoscope?

I'm looking into purchasing a used 2018 GT. I have the service records and I can see that the PCM was updated as per the recall at ~14,000 km. Hoping that the rocker arm did not become displaced during that driving period...
Unfortunately the cylinder deactivation recall by Mazda doesn’t include ANY verification of fallen rocker arms. And there’s no symptons of fallen rocker arms until you need engine power the most and that coukd put you in very dangerous situation like Go Hawks experienced. You should do some WOT test described in this thread on the highway making sure the CX-5 won’t get into the limp mode.

Dangerous cylinder deactivation trouble on 2018 CX-5 and 6 models

NHTSA Recall Campaign No.: 19V-497-000

It behooves everyone with a 2018/19 2.5NA to put it in manual and wind it out to 5k and keep it there for a minute, whether it's had the fix or not.

What are you waiting for?
No, not literally a minute. Just a few seconds, Maybe between 5-15 seconds. Remember, all you are trying to do is see if the computer senses a *misfire* on a cylinder due to the air/fuel ratio not being correct. So it may sense it as soon as you get above 5500 rpms or it may take it a few seconds to sense it. Mine happened when I was passing a vehicle. I was accelerating and keeping the RPMs high when it would go to limp mode.

And more to read:

Cylinder Deactivation Update