18' CX5 Limp Mode at Redline

J

jjm86m

:
2018 Mazda CX5 Machine Gray
So I was at a stop light the other day in a lane that was going to merge from 3 to 2. There was a Rav4 next to me and I took off to merge. Long story short, I decided to beat the RAV4 to the merge point rather than wait for them to pass, so I mashed the gas. I was in 2nd gear and saw I was almost redline and then all of a sudden the CX5 went into limp mode, engine check light, warning lights, everything. I thought that was really strange because I was in Auto mode and had no control of the shifting.

I understand the limp mode in the sense that it will happen if you push into redline, I was confused as to why that is allowed in the first place rather than shift prior to redline so it never hits that limp condition. I had to pull over and restart the car and the faults were cleared.

I thought this was an anomaly but it happened again while I was really mashing the gas on a bridge. This was a bit scarier because I didn't have a place to pull over. I guess the lesson here is don't go to redline or try to treat the CX5 like a race car but I mean, I'm not the one shifting here.

Thoughts? Has this happened to anyone else?
 
I would consider that to be a problem. And a safety problem at that. Suggest a trip to the dealer.
 
jjm86m said:
So I was at a stop light the other day in a lane that was going to merge from 3 to 2. There was a Rav4 next to me and I took off to merge. Long story short, I decided to beat the RAV4 to the merge point rather than wait for them to pass, so I mashed the gas. I was in 2nd gear and saw I was almost redline and then all of a sudden the CX5 went into limp mode, engine check light, warning lights, everything. I thought that was really strange because I was in Auto mode and had no control of the shifting.

I understand the limp mode in the sense that it will happen if you push into redline, I was confused as to why that is allowed in the first place rather than shift prior to redline so it never hits that limp condition. I had to pull over and restart the car and the faults were cleared.

I thought this was an anomaly but it happened again while I was really mashing the gas on a bridge. This was a bit scarier because I didn't have a place to pull over. I guess the lesson here is don't go to redline or try to treat the CX5 like a race car but I mean, I'm not the one shifting here.

Thoughts? Has this happened to anyone else?
Click to expand...

Redline doesn't trip limp mode by itself. However, multiple misfires will cause limp mode. This is where the $5 obd2 reader shines, because a lot of shops/dealer will charge a diag fee.. which might be $80, to read the exact same CEL. Also, even though your cel light may not be on, whatever caused the limp mode should be stored as a "historic fault" when read.
What's your mileage? High RPMS + these conditions: fouled plugs (maybe you usually drive lower rpms) low quality gas (cheap gas), high outside temps etc can all contribute to this. The fact that it repeated at redline points to a misfire imo. Add some quality fuel cleaner on your next fill up. Believe it or not that CRC "guaranteed to pass" is a very good cleaner (and it does clean up your catalytic converter, always good at any mileage). Also Rislone gasoline treatment works well too. They are ~$10 at Walmart. I ring my 93 tuned engine (with increased redline) every single time I drive it and I don't get misfires until a plug needs to be replaced. However I also service the fuel/emission systems regularly.

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There is something wrong. You have to know this is not normal behavior on any car.
 
Even in manual mode, Ive redlined my 13 and the transmission shifted itself anyway rather than let it continue at that rpm. No limp mode or anything. It shouldnt do that in the auto mode either.
 
jjm86m said:
I understand the limp mode in the sense that it will happen if you push into redline, I was confused as to why that is allowed in the first place rather than shift prior to redline so it never hits that limp condition.
Click to expand...

Faulty understanding there. That should not happen for that reason.
 
Not normal at all. I've floored my CX, and held it to the floor, many times and never had an issue.
 
Take you car in ASAP if you have not done so already. This is a known problem. Chances are you have a rocker arm that has fallen off of Cylinder #4 caused by the cylinder deactivation system at some point. Read my post *dangerous cylinder deactivation problem on 2018 CX-5 and 6 models*. This problem almost killed my wife and I. They had to replace our engine because of this. I have been going round nd round with Mazda for months trying to get them to recall these vehicles.
 
Thanks GoHawks. I took the car to the dealership and the diagnostic test was P0304=Cylinder 4 Misfire. They did reflash the PCM and the problem seemed to have been resolved with the flash. I asked them if this was simply software or if it was hardware related. They said software only but now you've got me wondering if they even checked anything on the engine.
 
jjm86m said:
Thanks GoHawks. I took the car to the dealership and the diagnostic test was P0304=Cylinder 4 Misfire. They did reflash the PCM and the problem seemed to have been resolved with the flash. I asked them if this was simply software or if it was hardware related. They said software only but now you've got me wondering if they even checked anything on the engine.
Click to expand...

Hey I called it. I'd still run a cleaner for good measure.
 
Last edited:
jjm86m said:
Thanks GoHawks. I took the car to the dealership and the diagnostic test was P0304=Cylinder 4 Misfire. They did reflash the PCM and the problem seemed to have been resolved with the flash. I asked them if this was simply software or if it was hardware related. They said software only but now you've got me wondering if they even checked anything on the engine.
Click to expand...

Its good that they reflashed your PCM. But, I would bet a lot of money that your trouble is beyond that. You coded a misfire on cylinder 4. Exactly as mine did. This is due to a missing rocker arm and only one of two intake valve stroking. You car will run fine at lower rpms because it is getting what the computer senses as enough fuel for that rpm. But when you rev the engine high enough it senses a problem with that cylinder and throws it into limp mode and throws the misfire code along with a bunch of other stuff. Take your car back in and have them remove the cylinder cover and visually inspect. You may get a new engine.
 
Go Hawks said:
Its good that they reflashed your PCM. But, I would bet a lot of money that your trouble is beyond that. You coded a misfire on cylinder 4. Exactly as mine did. This is due to a missing rocker arm and only one of two intake valve stroking. You car will run fine at lower rpms because it is getting what the computer senses as enough fuel for that rpm. But when you rev the engine high enough it senses a problem with that cylinder and throws it into limp mode and throws the misfire code along with a bunch of other stuff. Take your car back in and have them remove the cylinder cover and visually inspect. You may get a new engine.
Click to expand...

Seconded. If you get pushback from the dealer, reference Go Hawks' thread here, and if you have to, escalate to Mazda Corporate.
 
sm1ke said:
Seconded. If you get pushback from the dealer, reference Go Hawks' thread here, and if you have to, escalate to Mazda Corporate.
Click to expand...

Thanks sm1ke. Also, if you would like more info or you dealership has anyquestions concerning this. They can call my dealership and talk to The service manager there. Not sure if I can post the dealership name here, but its the only Mazda dealership in Pasco Washington. ��
 
Go Hawks said:
Its good that they reflashed your PCM. But, I would bet a lot of money that your trouble is beyond that. You coded a misfire on cylinder 4. Exactly as mine did. This is due to a missing rocker arm and only one of two intake valve stroking. You car will run fine at lower rpms because it is getting what the computer senses as enough fuel for that rpm. But when you rev the engine high enough it senses a problem with that cylinder and throws it into limp mode and throws the misfire code along with a bunch of other stuff. Take your car back in and have them remove the cylinder cover and visually inspect. You may get a new engine.
Click to expand...
I agree with you that OP has exactly the same problem like yours. Re-flashing the PCM can only mask the problem more.

I believe the dislodged rocker arm has to be the very last one which has nothing to stop it fallen off. But I wonder why Mazda gave you a new engine (actually most likely it's a factory rebuild) as the rocker arm should be able to easily to put it back to its originally position if the new PCM firmware can really control the oil pressure better?
 
yrwei52 said:
I agree with you that OP has exactly the same problem like yours. Re-flashing the PCM can only mask the problem more.

I believe the dislodged rocker arm has to be the very last one which has nothing to stop it fallen off. But I wonder why Mazda gave you a new engine (actually most likely it's a factory rebuild) as the rocker arm should be able to easily to put it back to its originally position if the new PCM firmware can really control the oil pressure better?
Click to expand...

The dealership said Mazda was taking all of the engines back that were experiencing this issue at the time. Not sure how they are handling it now. My car had less than 9000 miles on it when they replaced the engine.
 
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