Cars, etc.

[OldAIMGuy]

Hi Bob, Re: STi..................

It looks like the engine's computer is keeping it pretty lean until the throttle position sensor, etc. sees you're interested in something else than fuel economy! Then is opens up the quart jars of petrol and pours them in.

I remember working on the mechanical fuel injection on a six cyl. Mercedes of about the late '60s era, I believe. It was my first (and I hope my last) attempt. There were more adjustments to fiddle with than I could keep straight. I followed the book (not easy for me!) word by word and when I was through it ran fine, but it didn't fix the problem that was there at the beginning! (car started fine cold, but wouldn't start off the key when warm - but would bump start easy as can be when warm)

I don't think anyone ever did figure that one out.

EFI, for all its mystery, is rather magnificent. There's still a ton of stuff that has to work right and work together to make it do what it's designed to do, but it's very good. And having a chip with a map of what's supposed to be the proper fuel delivery at every RPM and every throttle and load combination - well, I don't want to work on them, either, but I certainly am impressed.

I've read about the programmable chips and software. I guess you can develop your own profiles right on a brake dyno doing the same thing and then then burn the results to an EPROM and run your engine that way. Very cool. Now all we need is a full brake dyno at our disposal!!

Best regard, Tom