How do ya do it? I have an rx8 rotary im putting in my 1976 fiat 124, and i'd much rather prefer to have a cable throttle body. I have the stock ecu, do you guys think this would mess with anything pertaining to the engine? Is it typical for the ECU to get inputs from throttle position or just outputs, I know it gets inputs for traction control, but if it doesnt affect the engine running i dont care. First time working with a newer engine like this with electronic throttle so any advise is appreciated.
It is not just "inputs" and "outputs" so much as the accelerator pedal is merely a torque request and the PCM decides how best to make that torque. Throttle position is just another way of altering torque. Throttle position is an output, not an input.
If you want to use the stock PCM, you need to have drive by wire.
The only way I can see would be to find a throttle position sensor that matches the output of the stock pedal or add a cable that activates the stock pedal resistor.
I know nothing about the engine you are using, but other drive by wire engines i have laid hands on didn't have an iac valve. I think you are opening a can of worms if you try to switch to a cable.
pjbgravely said:
The only way I can see would be to find a throttle position sensor that matches the output of the stock pedal or add a cable that activates the stock pedal resistor.
The problem with that is that your pedal does not correspond to a throttle position- it's asking for a torque demand.
There's no real way to use the original ECU and take off an electronic throttle. Even if one could hack it, the entire way the code runs is around the electronic throttle- it's not something you can just turn off.
E-throttle isn't necessarily bad, in fact it's theoretically better and allows for some features that would be impossible with a cable throttle, stick to it.
alfadriver said:
pjbgravely said:
The only way I can see would be to find a throttle position sensor that matches the output of the stock pedal or add a cable that activates the stock pedal resistor.
The problem with that is that your pedal does not correspond to a throttle position- it's asking for a torque demand.
There's no real way to use the original ECU and take off an electronic throttle. Even if one could hack it, the entire way the code runs is around the electronic throttle- it's not something you can just turn off.
You could use the throttle cable to control the "APP" sensor. That way you keep the existing pedal structure.
Honda does it this way on some of their earlier J-series sixes - they run a regular ol' throttle cable out under the hood to the APP sensor. So they do get the drivability advantages of drive by wire, but they miss out on the faster assembly-line process.
If the engine is behind me, I’d rather run wires to the ECU than a cable to the throttle :)
DBW is great if programmed well.
alfadriver said:
pjbgravely said:
The only way I can see would be to find a throttle position sensor that matches the output of the stock pedal or add a cable that activates the stock pedal resistor.
The problem with that is that your pedal does not correspond to a throttle position- it's asking for a torque demand.
There's no real way to use the original ECU and take off an electronic throttle. Even if one could hack it, the entire way the code runs is around the electronic throttle- it's not something you can just turn off.
I didn't say it would be easy or even work correctly.
In reply to pjbgravely :
I'm saying that it wouldn't work. At all. The whole structure of current ECU code is dominated by the electronic throttle, so if it sees a fault, it won't run.
Doing an MS system or keeping the ETC would be a doable path.
Knurled. said:
alfadriver said:
pjbgravely said:
The only way I can see would be to find a throttle position sensor that matches the output of the stock pedal or add a cable that activates the stock pedal resistor.
The problem with that is that your pedal does not correspond to a throttle position- it's asking for a torque demand.
There's no real way to use the original ECU and take off an electronic throttle. Even if one could hack it, the entire way the code runs is around the electronic throttle- it's not something you can just turn off.
You could use the throttle cable to control the "APP" sensor. That way you keep the existing pedal structure.
Honda does it this way on some of their earlier J-series sixes - they run a regular ol' throttle cable out under the hood to the APP sensor. So they do get the drivability advantages of drive by wire, but they miss out on the faster assembly-line process.
You could, or you could just mount the pedal sensor in the pedal....
Back in the early 90's, when ETC was being develpoped, there was a cable system that was supposed to work with ETC... Other than the one prototype, I never saw another.
