Was just talking to evil about a potential replacement for the MPS and came up with the following question:


Is it possible to replace the MPS with some sort of chip / solid state component that emulates the readings that the MPS gives off throughout the range, but is instead driven by engine RPM, throttle position, etc?

If that wouldn't work, why?


I don't pretend to know much about djet, but it dawned on me that I could program a chip that maps various readings to the rpm range. Might take a bit to get the curve right for part throttle response but...is it doable?

Not a new concept. Just nobody knows how to do it - yet. Hopefully someone will figure it out. But it isn't simple by any means. Read the last few posts of this thread:

mps thread

Megasquirt?

I'm sure its been discussed many times over the years, the conversation evil and I were having just got me thinking.

Being a programmer, I think I could build something that could do this.

For one the fuel required is measured by need/load. When you have your foot to the floor, the chip would not know how much fuel is required because the rpms do not immediately rise with the throttle opening. You could design it that way if you changed a few other things.

I see what your saying Thack. I revised my original post to include throttle position as an input as well....


stamping a basic chip to do something like this is not tough to do at all...finding the correct algorithim for the output however...

It sounds like you are on the right track. Maybe you can develop what you can and then someone else can come up with the engine vaccuum interpolation. Because when you go uphill and need more fuel to maintain speed that has to be addressed also.

yeah exactly, that was the piece I was missing. You need to measure load somehow...

MAP sensor to measure vacuum as the MPS does.

Software to convert MAP data to match MPS info. This is not a linear curve. Need a different curve for each of the 3 MPS.

Interface to "Brain" that looks like the MPS output inductor.

Ken

Read my blog. One of the earlier posts discusses this. The short version is that by the time to put together the electronics to emulate the MPS, you're 90% of the way to a full fuel ECU, so you might as well just spend the much smaller amount of money on a Megasquirt, which uses a solid-state pressure sensor, and thus doesn't need the MPS.