Automatic Shifting
 

Hey guys, I unfortunately let a friend take my car around the block yesterday. He drives stick normally so he used the manual option and went down the street. He said he went to redline first, and he said it didn't reach the redline before it automatically dropped the rev's down on him. All this while maintaining first gear. Almost as if it lost power and was shutting down. It didn't in fact shut down and the idle remained strong afterwards as I have a brand new reman. engine from Mazda. (3000 Kilometers on it)

Any insight as to what this may be or if it is something I should look into further? I normally redline second or third since the engine break in period and haven't myself redlined first.

Thanks, if any other info is needed let me know.

I'm not fully knowledgeable about the ins and outs of the AT shifting logic, but was it warmed up the whole way? I could see the ECU forcing a shift under various circumstances. "Manual mode" isn't a physical link at all, you are just disabling some of the shifting logic to be able to tell the ECU when you want it to shift. It will still auto-shift into 1st when coming to a stop, for example. I fully expect there are plenty of other points where it will auto-shift when it sees something it doesn't like.

Yes, the odd part was, was that it stayed in first. I could understand if it automatically shifted into second, but the revs hit around 6 or 7k and then just dropped on their own. The car was completely warm, had it on the road for around 40 minutes. From what I've experienced, it downshifts on its own, but doesn't upshift until you shift it.

What you are describing is sounds like it has nothing to do with shifting logic, and instead ECU accelerator pedal logic.

It is also something that can happen on MTs too. There is safety logic in the ECU to prevent vehicle fires. Back in the mid 2000s, there were a couple vehicle fires in other Mazdas (Mazda5 was one I remember) where the exhaust was overheated from extended high RPM at too low of a vehicle speed, so logic was instituted across all drive by wire Mazdas (which all RX-8s got courtesy of the various vehicle reflash recalls) that under certain conditions of RPM, time above an RPM, and vehicle speed, the ECU will stop obeying the accelerator pedal and return the throttle to the idle position. It will continue to ignore the accelerator pedal commanded value until the pedal is released.

I've had mine actually shift gears on me while driving. Was in 2nd doing about 70mph and it shifted into 3rd by itself. Has only happened once, but really troubled me as to why.