Just some questions about the workings of the ECM. I got a salvaged 05 MT rx-8 that sustained some flood damage. The ecm died. The car has 3000 miles on it, I am ordering an ecm from a wrecked 04 MT with 26000 miles on it (so I assume it has had some flash updates). Will this ecm work? Will it make my car show 26000 miles, where is the mileage stored? Can't seem to find a straight answer in the forums. Will my keys still work (I hear something about the immobilizer system). I know its a lot of questions but I am anxious to get this baby running. Thanks

 

No, it would at a minimum need to be reprogrammed. You have to have the correct part # computer to match the one in your car, it cannot be any RX-8 computer. A 2004 model computer for a 2005 vehicle is going to be an issue. If you have a 2005 6 spd model then most likely your computer ends in "-881B". Good luck finding one, I had a b-tch of a time

However, I am getting conflicting information on whther or not the dealership can flash over the information from your computer onto that from another car. It doesn't make sense to me that they couldn't. The problem is it's not a common enough situation and I've been unable to get anyone to give me a confirmed answer, including Mazda Motorsports

I don't claim any of this to be 100% fact, it's hard to find anyone who can accurately answer these questions. If you find out/prove differently please let us know

 

The speedometer, odometer and trip meter are controlled by the instrument cluster microcomputer, so accumulated mileage is likely to be store within that system. In which case your odometer reading would not change unless you replace the instrument cluster unit.

The immobilizer system and the keyless control module are separate components but I don't know how autonomously they operate and what role the PCM plays in their operation. Like just about everything in the car, they do connect to the PCM. I think worst case, you will have to get a dealership to program in your keys/remotes.