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

jjm86m said:

Lol. That would seem to have put them in a position where they would've had to acknowledge the issue.

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Update: CX5 was dropped off at the dealership this morning. Dropped off the Service Alert that was posted here on the forum and explained the situation. As expected there was push back from the service guys since "the reflash PCM solved the issue and there are not codes being shown right now, so we can't just go checking things that aren't wrong". I countered with the fact that 1. I have the previous service receipt showing the problem has already occured once 3. The documented SA shows a known existing issue 2. I have no interest in spending more time at the dealership than I have to and I have better things to be doing (work) 3. I wouldn't be here if I felt that all aspects of the problem were resolved, and vehicle was safe to drive and 4. I'm as uninterested in chasing ghost issues as they are..

Ultimately they agreed to have a tech look at the situation but did not commit to performing the visual check. It's been almost 7 hrs and I haven't heard a peep from them. My hypothesis is that they are actually working on this in some capacity since I have their courtesy vehicle and they probably want it back asap...... To be continued.

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Tran7270 said:

If CD does not exist, then there would be no CD related problem. There would be no CD related part failures.

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jjm86m said:

...My hypothesis is that they are actually working on this in some capacity since I have their courtesy vehicle and they probably want it back asap...... To be continued.

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yugrus said:

Umm. Don't hold your breath. From my experience they will just call you back at the time they realize they have someone's car on the lot, and their loaner missing. Saying the car is ready to go, nothing is wrong with it...
That's what it takes to shrug the customer off of their shoulders. Who knows, you might like your loaner better and trade...

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MyFirstMazda said:

I think they have to take a visual look because they skipped that step in the original diagnosis. A visual inspection is now done first, and after that the 'normal' diagnosis is done if the rockers are fine. And they should have a work order that says they looked and the rockers were fine or not.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10159203-0001.pdf

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MyFirstMazda said:

I think they have to take a visual look because they skipped that step in the original diagnosis. A visual inspection is now done first, and after that the 'normal' diagnosis is done if the rockers are fine. And they should have a work order that says they looked and the rockers were fine or not.

https://static.nhtsa.gov/odi/tsbs/2019/MC-10159203-0001.pdf

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Tran7270 said:

MyFirstMazda said:

Good question, about CD when in sport mode. Idk. However, running in CD isn't the problem. Having defective software or part in the CD system caused the problem, based on reading this thread and the service bulletin.

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If CD does not exist, then there would be no CD related problem. There would be no CD related part failures.

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Tran7270 said:

yrwei52....So CD engages even in Sport mode?

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MyFirstMazda said:

Yes that is true. But driving such that deactivation does not occur does not remove the oil control valves or the sophisticated lifters required for CD or the oil pressure control. Those parts can be defective and have a failure such that the rocker brakes or falls off without deactivation ever occurring. Go Hawks doesn't know when his fell off, it might have happened on the test drive. It might have been off when it left the factory.

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Whiter0se said:

Do we know if cylinder deactivation work while the car is idle at a stop light?

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David Paul said:

Whiter0se said:

Do we know if cylinder deactivation work while the car is idle at a stop light?

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Not unless you can travel at least 20 mph while sitting there.

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yrwei52 said:

...
The fuel saving feature while the car is idle at a stop light is "i-stop", which is not available for US market.

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Whiter0se said:

What I do notice is that sometimes after stopping at a light, when I let go off the brakes to creep up a bit, the body of the car feels like it drops an inch or two from behind. As if the back is higher than the front. When I let go, the back feels like it comes down a inch or two.
Another observation is that, the engine likes to idle at around 500rpm while at a redlight, if I let off the brakes without the gas pedal, the RPMs climb up to 750-800.

Not sure if it was cylinder deactivation at play here but not what I'm used to.

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Whiter0se said:

What I do notice is that sometimes after stopping at a light, when I let go off the brakes to creep up a bit, the body of the car feels like it drops an inch or two from behind. As if the back is higher than the front. When I let go, the back feels like it comes down a inch or two.
Another observation is that, the engine likes to idle at around 500rpm while at a redlight, if I let off the brakes without the gas pedal, the RPMs climb up to 750-800.

Not sure if it was cylinder deactivation at play here but not what I'm used to.

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Go Hawks said:

This is a long read but hopefully it will get the attention of the right people and quite possibly save a life.

My wife and I own a 2018 Mazda CX-5 Grand Touring. We purchased the vehicle to replace our 2014 Mazda 6 GT. Being the proud Grandparents of two beautiful little girls, we wanted a vehicle that was easier for us to get them and their carseats in and out of. The CX-5 is perfect for that and we were extremely happy with the vehicle until it almost caused us to be in an accident that could have killed us both.

For the year model 2018, Mazda added cylinder deactivation to the engines that are installed in both the CX-5 and the Mazda 6 models. Unfortunately this system is what caused the trouble for us and, at last count, at least 26 other customers that Mazda has confirmed.

My wife and I were on vacation following a car on a curvy mountain road. I had the CX-5 in Sport mode. At one point the vehicle in front of us pulled over for us to go around them. As I accelerated to go around the vehicle, our car cut out and went into limp mode. The dash lit up with alarms and we had to pull to the side of the road due the limp mode not allowing the engine to rev past 2500 rpm. Our vehicle is equipped with a camera for automatic braking, lane identification, and cruise control. The alarm on our dash read Automatic braking system failure. This alarm led me to believe our trouble was with the camera. We were able to reset the alarm and the limp mode by simply shutting the car down and restarting it. Upon restarting the car, all alarms would clear and the engine would rev as normal. 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.

The previous times that we had trouble were all in daylight hours and accelerating around a vehicle to pass. On this final time it was dark and we were following a semi truck on a two lane highway in central Oregon. I had the opportunity to pass the semi. I accelerated and moved into the oncoming lane to go around the truck and trailer. Just as we were moving back into the lane in front of the semi, the car cut out and went into limp mode again! We basically were straddling the center line with a dead vehicle and an 80,000 lbs semi getting ready to roll over the top of us or push us off of the road. Luckily no cars were coming from the other direction. The truck driver slowed down enough for us to limp ( going 65 mph) across in front of him to the edge of the road and stop. At this point we realized that it wasnt the camera but had something to do with accelerating the engine. We reset the vehicle again and didnt take the car over 4000 rpm for the rest of the way home.

We were able to take the car to the dealership 2 days later. I described the issue we were having and that we thought it was something with the engine. They took the car into the shop and after an hr came and told me that the problem was fixed. They had called Mazda and were told the issue was with the camera. They reprogrammed the camera controller upon Mazda recommendations. I argued with them and explained again what we had seen and that we thought the trouble was with the engine. They said that I had to take the car and if it happened again to bring it back. I told them that the car was unsafe and it was poor of Mazda to think a customer should take an unsafe vehicle on the road. I left the lot and went straight to the freeway and duplicated the problem again. This time, as I sat on the shoulder of the freeway, I videoed the dash for them to see. Reset the car and headed right back to the dealership. They gave me a loaner (another CX-5) and said they would call me when they had it figured out. Two hrs later the service manager called me and said they had it figured out. A rocker arm had fallen off of cylinder #4 and they were going to be replacing my engine. They had called Mazda again and the engineers had told them to remove the valve cover and look for this issue. Mazda had seen it before and our car was number 19 with this issue. When I asked how that was even possible the dealership couldnt answer my question. They had my car for a couple of weeks and replaced the engine. When we went to pick it up, they still couldnt tell me why it happened. We refused to take the car until we knew why it happened and if the issue was fixed. The service manager agreed with us and kept us in his loaner for another week. At this point I told the service manager that I wanted to talk to someone at Mazda corporate to see if I could get some info from them. He gave me their number and I called them the next day. I explained the whole thing to them and how I didnt feel safe taking a vehicle with no explanation as to what the cause was. A case file was opened with them and they stated that they would be keeping me informed. A few days later I received a call from corporate customer service with an explanation. They told me the problem was caused by a low oil pressure on cylinder #4 which enabled the rocker arm to dislodge. The remedy was to reprogram the main PCM to not allow the pressure drop. Mazda corporate was sending the tool to my dealership to reprogram the PCM. This was done and supposedly our car is now fixed. Now, here is the huge problem and why this could possibly kill someone or may have already done so. There is no indication as to when this rocker arm fell off. The computer senses nothing. It could have been off for months! Once that rocker arm falls off the car still runs fine, as far as the computer is concerned. On our vehicle it was a rocker arm on an intake valve. The computer senses nothing wrong with that cylinder until the rpms get high enough that the cylinder cant keep up the burn and then it finally throws the cylinder misfire code and sends the engine to limp mode to protect the engine. This is deadly! It happened to us when we were passing. We need the engine at that point. If it miss fires on one cylinder you probably can still get out of harms way if need be. But you certainly cant when it goes into limp mode.

When we went to pick up our vehicle, I asked the service manager if the reprogrammed all of their cars on the lot that have the same engine as ours. He said they had not since Mazda didnt recommend it. This makes no sense. Why would they not reprogram every vehicle to prevent this problem?! I also told them that the logic of sending the car to limp mode at the rpm is going to kill someone and needed to be changed. We took our car and went home. This was on a Friday (black Friday actually) and this ate at me so bad all weekend that I went back to the dealership the following week to demand to talk with someone with some technical background in corporate to express my concerns about the safety of these vehicles. Before he got me in touch with corporate, the service manager told me that Mazda has found the source of the problem. Apparently Mazda has 2 suppliers of PCMs. One of the suppliers has the wrong program installed on all of their PCMs that they have sold to Mazda! Mazda is currently trying to figure out what vehicles have these PCMs installed so they can get in touch with the owners. When he told me this I lost it! Again I asked him why the heck Mazda doesnt just reprogram all vehicles on every lot and recall every one of these vehicles so they can reprogram them and be done with it. They are going to wait to try to figure out which vehicles are bad? Meanwhile women and children are driving around in these cars and they may have a huge problem and not even know it!! I was able to talk with the west regional tech support. (John). Expressed my concerns, he agreed with me but stated that possibly Mazda was going to collect some data from the cars that have been reprogrammed to make sure that this is the fix. I told him that I wasnt going to be a Guinea pig for Mazda by testing their fix for them and end up wrapped around a pole somewhere because the fix wasnt right!!

I have contacted Mazda corporate customer service again and expressed my concerns about recalling all of these cars and reprogramming the PCM and changing the logic to not have it go into limp mode at those higher RPMs. I was told by them that Mazda will not be doing that and my car is considered to be fixed.

So we now have a car that may be fixed but gives no indication of a problem if this happens again. My wife is afraid to take the Grandchildren in it because she feels it isnt safe.

Please tell anyone you know who has one of these vehicles to get in into the shop asap. There is a technical service bulletin that Mazda just released to the dealerships for this issue.

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MyFirstMazda said:

jjm86m what did they find? Do they still have your car?

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