The rocker arm literally falls off. It was laying down by the valve port. The engine runs fine during idle and lower RPMs due to the fact that it has four valves per cylinder. The computer only senses a problem at higher revs. At this point it senses a lean situation on #4 cylinder (in my case) because one intake valve is not stroking. This is what makes this situation so deadly. You as the driver have no indication or idea that you have a problem until you are reving the engine and need the power and suddenly the computer senses trouble and throws the engine into limp mode. As my first post indicated, it happened to us when we were passing an 18 wheeler at night. This is what I was, and still am so furious about. We as the drivers of these vehicles have no idea something is wrong untill it is too late. This happened months ago and I am bringing this up now again because I just took our car in for an oil change and talked with the service manager about all of this again. He stated that since my car left and one other one they had to change the engine in, there has been nothing from corporate about this situation. Total silence!! So I figured I would try to see if I could get the word out to people about this since there has been no recall or really any action from Mazda. I am concerned that there may have been people already in accidents or possibly killed due to this issue. This could easily cause a head-on collision and at that point people would just think it was driver error or ignorance not knowing that the cause was mechanical failure.I still wonder how the engine runs fine in idle with dislodged rocker arm... And how the arm is allowed to slip on the shaft. Perhaps, that lateral movement is by design to shut the cylinder off by missing the valve. And increased oil pressure is supposed to bring it back over the valve.
Ok, I think it now makes sense, if that's the case. Rocker arm slipped to de-activate the cylinder on the highway, then there wasn't enough oil pressure to get it back over the valve when full power is commanded. Fuel is injected, but no combustion. PCM hits panic button, lighting up the dash and invoking limp mode.
On restart the PCM commands full oil pressure, the arm gets back over the valve.