Here's the latest update I have.
- A new engine has been authorized by Mazda Corporate.
- According to the technician this is a new engine, not a refurbished one
- I pressed the service guy to call the Mazda Field Service Engineer to find out why they are confident this engine won't fail. They ultimately came back to the same answer they gave to Go Hawks. The PCM update is sufficient to keep oil pressure to keep the rocker arm from falling off.
- Should take about 1.5-2 Weeks for engine delivery and installation
I'm currently in a 2019 CX5 Touring courtesy of the dealership and have put on about 1000 miles since I got it. I have been trying all sorts of different combinations to see if this is repeatable with this particular car. I've gone to redline from a stop, from a constant 45mph to redline, from 60mph to redline and downshifting to get to redline. I haven't had any issues and the loaner drives just fine.
If its gnawing at you to know if you're affected, here are some of my observations and thoughts regarding my case.
1. I observed noticeable slowness while merging into and out of traffic on the freeway. I would see a gap i would want to merge into but the car would be too sluggish to react when I gave it gas and the gap would close and I'd miss the merge. I attributed this to the fact that I was used to driving an Acura RSX and went from zipping around in traffic to an SUV. I didn't have a baseline comparison. The loaner CX5 is much easier to maneuver in traffic and I can tell a difference. Take note if you feel like your CX5 is unusually sluggish.
2. City Gas Mileage. My city gas mileage was really poor 17-20mpg. I thought my aggressive driving style led to the terribleness in city mpg but the rocker arm falling off may could have been more of a contributor. On the 19' touring my city gas mileage is much better (~25mpg). The 19' is a FWD compared to my AWD but 17-20 was still low in my opinion. My highway mileage was actually not bad and actually stayed in the 29-31 range.
3. Noise. when slowing moving through a parking lot, or at a stoplight I would sometimes hear inconsistencies in engine idle (possible rattle?). Nothing ever enough for me to complain to the dealership about bc it was inconsistent and super faint. I am speculating that was due to the rocker arm rattling around. I haven't heard that on the 19' I'm driving.
If you're have the combination of issues I've noted above then you may want to check with your dealership to discuss the symptoms you are seeing. I would avoid allowing them to update the PCM because if you're rocker arm has fallen off that will only mask the problem because even with the rocker arm off, the flash does "fix" the issue.
I have an open case with Mazda Customer Support Right now and I want to talk to them about having them add the affected PCM versions to the TSB. It doesn't do the service guys any good if they don't know which PCM versions are bad. They're only reactive to the codes thrown or customer complaints of low power. If it truly is a case of the wrong PCM version then its not that hard to identify if you're affected. Maybe that makes too much sense for Mazda.