I posted this in the "Tech Garage" forum but it didn't get much traction, so let's try here:

I'm contemplating a project which for now I will not detail such that we can all concentrate on the question at hand

Does anyone have any experience or information regarding the effects of removing the stock ECU? The "new" motor would be running off a Haltech (or equivalent) and would not need the stock ECU for any engine related functions. My questions are really related to the ABS, and Electric PS - the car is to become mostly a track vehicle with some occasional street use, so other ammenties such as AC aren't really much of a concern. Looking at a quick wiring diagram it doesn't seem that the ABS or EPS are attached to the main PCM, rather run off their own mini-ecu's which primarily require a connection to the VSS (vehicle speed sensor) in order to function. Does this mean that removing the stock ECU would not affect these functions?

I had originally planned on leaving the stock ECU in place, but it's mounting and cable routing may interfere with the positioning of the new engine. I'd prefer to remove it alltogether if possible.

If anyone has any information regarding this it would be greatly appreciated - I am awaiting my RX8 Wiring Manual so am posting this question prematurely!

Thanks in advance...

 

What "New Motor" are you considering? V10, V8 ,V6 or Rotary Power?

 

I'd rather not say for now, just so I can try and get some answers to my question rather than arguments on the merits of my swap

 

In my understanding, the stock ecu has its grubby little paws in a significant portion of the car's electronics. Gauge cluster, A/C, ABS, DSC/TCS, PS, TPMS, drive-by-wire throttle, etc. I wouldn't be suprised if the headlights, radio, power locks/windows/mirrors, and rear defogger didn't work without it :D . It'd be my guess, that you'd need to keep the stock ecu along with the stand alone, though getting the stock one to ignore the engine management could be a challenge.

 

I won't be using the AC, DSC/TSC, TPMS or the drive-by-wire systems at all (new engine doesn't have such a thing, just a cable). The stock ECU won't have a choice BUT to ignore the engine management as it won't even be connected to the engine anymore. The Haltech controls the ignition, fuel injection, fuel pump, and all other engine functions. I guess you could say that the only vital function I'm concerned with is the electric power-steering and ABS.

 

why leave the stock ecu in at all?

 

so ittl run the guages etc?

 

Because I'm worried that it has an impact on the power steering (which is electric) and the ABS. My concern is that the VSS goes into the main ECU which then outputs the vehicle speed to those 2 circuits.