simple analog fuel injection
Bruce Plecan
nacelp at bright.net
Tue Jun 23 01:58:13 GMT 1998
-----Original Message-----
From: Ron Tyler <dcmckenna at worldnet.att.net>
Subject: Re: simple analog fuel injection
You will need to have a gain and an offset pot.
>> The gain sets the slope of the pulse-width versus MAP, and the offset
>> pot shifts the whole curve (or rather, straight line) up and down the y
axis. You can even use the offset pot as a manual 'choke' equivalent.
>> The system won't be as good as a real modern EFI, but I have found that
>> on a small tuned 4 cylinder engine (998cc Hillman Imp) it works better
>> than the old twin 1.25 carbs ever did. (I only suggest you try this on
>> vehicles that aren't subjected to stringent emissions checks.
>>
> Chris,
> I'm not a hack, but I am familier with the 555. I believe I
>understand the concept, but I dont know how to build in "gain" for the
>MAP. Can you send me a schematic or mabey a brief verbal summary please?
>Also, how would you build in an "accellerator pump" with a TPS?
>Mucho Thanx
>Ron & Stephanie Tyler
%TPS change per amount of time. Or change of voltage per amount of time.
Remember you have 70% throttle opening at 20% throttle
travel. Then cold coolant correction. Air temp correction. RPM
Correction, gee gettin complex quick. I'm not at all trying to rain
on your parade. Within the last 6-7 months I think this very issue
accleration pump has been talked about. Think the final thoughts were 5
tables, corrections for it.
You can minimize these corrections IMHO by using a fuel pressure
regulator referenced to engine vac. But, still complex, to do right.
Also, intake tract ducting can help (ie real long in lenght).
If I had to do something along these lines I rack a bunch of 555's
together. Base Pulse width, then temp correction, then air correction
accleration/TPS, accleration temp, accleration MAP etc etc. add'em
up and then fire the injector(s).
Just some thoughts
Bruce One similiar project here at CSH, HQ was a traction
control device worked really nice then one night temp
dropped on test drive a couple degrees, and the car
could not be made to move, disable TCD and drove
home. Put device in freezer wouldn't work. Thaw to
34+ and it was fine. Could not be made not temp
sensitive. Months of work down the drain... Tandy
Corp stock rose $2/share over what I spent at radio
shack
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