Just a quick question.

I have been looking at the ECU pinouts to try and figure out the temp sender and temp gauge and their wiring.

As far as I figure I don't need the stock ECU in order to keep the coolant temperature gauge working properly. All I need is the temp sender and it's connection to the temp gauge in the dash.
Is this correct?

As far as the 85 MR2 ECU is concerned that is true

So in other words the L-jet fi will have a temp sensor for fi and a different one just for the water temp gauge

Hth