MoTeC Global Forum

I have an M4 in a group A Celica st165. The original group A ECU's from Toyota had two trim knobs:
-fuel from -2% to +4% in 4 clicks
-max boost from 2 to 3bar absolute pressure in even 8clicks.

How would you normally wire these to the M4? The knobs are digital: 2 outputs for 4 clicks and 3 to cater for 8positions. You could wire them to resistors to make a 0-5V signal out of it to save on inputs.

I want to replace the fuel trim with ignition trim to prevent for knocking. And keep the boost control.

Thanks!

Hi,
The M4 has a spare analogue volt and analogue temp input that you could wire two potentiometers to, we do not use the digital inputs like Toyota did. You could then calibrate the pots to be for a boost compensation and for an ignition compensation. You could even have one pot as a combination to alter fuel and ignition together.

That would work! Thanks.

I would want to keep the original knobs. Is there a simple way to turn the digital signal into a useful analogue one?

The outputs of the 8 step one is 000,001,010,....111.

1600hf wrote:That would work! Thanks.

I would want to keep the original knobs. Is there a simple way to turn the digital signal into a useful analogue one?

The outputs of the 8 step one is 000,001,010,....111.

got a photo of the switch itself?

I would just replace the internals with a proper potentiometer.