MS1/Extra Nerds! kPa Table Switching Circuit

Discussion about ECU Tuning Products and Theories
Post Reply
cmj
240sx Wannabe
Posts: 129
Joined: Fri Jun 27, 2008 3:12 am

MS1/Extra Nerds! kPa Table Switching Circuit

Post by cmj »

So I was pretty bummed when I got my MS1/E all built up and started making plans with it. MS1/E doesn't allow table switching via kPa (only via an input)! With the whole of MS1 being written in ASM, I don't have the time to go through the code and implement my own, so I decided to use the available input switching method.

I came up with a simple op-amp/comparator circuit that should fit the bill nicely. Theoretically (or ideally) the inputs of an op-amp are zero current or infinite impedance.. This should allow me to tap off of the MAP signal without causing interference. Someone please correct me if my thinking is wrong.

Anyway, Here is the tune-able circuit I have come up with.. I need to do a bit more MAP research to see what a usable voltage range for adjust-ability will be, but I think this is a good start.

Image

This should work... Right!? :)
Spoolin6er
Dreams of owning a 240!
Posts: 95
Joined: Tue Jul 03, 2012 2:30 pm

Re: MS1/Extra Nerds! kPa Table Switching Circuit

Post by Spoolin6er »

Ran across this randomly - did you ever get it to work?
cmj
240sx Wannabe
Posts: 129
Joined: Fri Jun 27, 2008 3:12 am

Re: MS1/Extra Nerds! kPa Table Switching Circuit

Post by cmj »

Yeah, this setup worked. I would suggest using a 10-turn 10k potentiometer and testing it on the bench first. It took me a while to get the correct voltage/kpa that I wanted the table to switch at. Also remember that the MAP sensor is not actually linear so although your calculations will get you close, it's better to use a pot. When I ran this setup I tuned the switchover to happen at ~115kPA it always took place within 5~10 kpa
Post Reply