8748 add'l injector controller design

[michael glidewell]

At 07:53 PM 5/6/96 -0700, you wrote:
>
>    I have completed the breadboard of my 8748 controller which drives 
>two 60 lb/hr injectors (using MC3484 peak/hold drivers). It works great 
>in my BMW 745i (factory intercooled turbo, 7-8 psi). I am now running 
>16-17 psi boost with no detonation - in fact, I think my fuel map is a 
>little too rich! (no oxygen sensor).
>     I have laid out the artwork for a two-sided PC board using Eagle 
>2.6, but have not had it fabricated yet (the first two boards are the 
>expensive ones - about $250-300 ;) It's not a very flexible design (map 
>is stored in EPROM), but it _is_ simple, with a low component count, 
>and the software is only about 100 bytes long (plus the 256 byte map). 
>The only expensive item (other than the PC board ;) is the 0-30 psig 
>pressure sensor with 0.5-4.5 volt output - cost me $43 from OMEGA.
>    Anyway, if anyone's interested I can post a ZIP file with the 
>schematic and the artwork (printable on a HP laser printer). It's only 
>about 60Kb compressed. Usual disclaimers about blowing up CPU's 
>and engines at your own risk, etc.
>    Next revision is to add a multiplexer to the A/D input (from the 
>pressure sensor) so that an oxygen sensor may be used for closed-loop 
>control.
>-Charles
\
Sounds very lilke a very ambitous  project! Is the 745i an L-jetronic or
Motronic? What did you actually replace on the stock unit?  Ihave a 528i
L-jet which I would  like to improve.
----------------------------------------------
Michael Glidewell       Boston, Massachusetts	glide at shore.net
KE1CP     BMW 528i      BMWCCA 		http://www.shore.net/~glide/