MAX - Read this ..... Re[2]: EFI Mapping Questions....

[avos at cochlear.com.au]

     Is it likely that the PROM in my car from JECS is compatible with 
     standard PROMs that can be brought from my local electronics stor ie. 
     Motorola etc., If this is the case atleast I can attempt to down-load 
     the data out of my existing chip with the PROM reader/writer that I 
     have.....
     
     Adrian


______________________________ Reply Separator _________________________________
Subject: Re: EFI Mapping Questions....
Author:  diy_efi at coulomb.eng.ohio-state.edu at INTERNET
Date:    23/5/97 14:29


> I have a question regarding the altering of EFI parameters from a 
>     factory Management computer. My car is a Subaru and I brought it with 
>     an after-market EFI chip installed by the previous owner. The chip was 
>     designed in Australia. I had a bit of a think about how to design such 
>     a chip, and came to the conclusion that modication of my chip would 
>     only be feasible for a small company if the chip was a standard PROM 
>     and the people who developed my chip simply down-loaded the data from 
>     the factory chip, worked out how the data effected the paramters of 
>     the management computer, and modified the data for new parameters, and 
>     then burnt a new compatible PROM with the data. Is this a way that 
>     aftermarket chips can be made?
 Yes
     
>     If this is the case and the aftermarket chip is simply a PROM, than I 
>     should be able to download the data from this aftermarket chip into a 
>     file and edit it, and burn a new chip. The main question I have is how 
>     do I find information on the PROM memory map?
     
That is the tough part.
     
> Is it likely that the makers of my aftermarket chip worked out how it 
worked by trial and 
>     error, or would they have had a manual which explained the memory map 
>     of the chip. Is it common for car manufacturers to give such 
>     information to the general public. If so where would I be able to get 
>     it for a Subaru Liberty RS Turbo.
     
No such manuals exist.  The information is not that hard to recognize if you 
know what you are looking for.  The fuel and spark tables usually stick out 
pretty well.  The tricky part is figuring out where the boost data is.  This 
is why you have to pay for a chip, because they did the work to figure it 
out, they are charging you for that work.
     
>     I have recently found out that another maker o EFI chips in Australia 
>     is making a chip which alters the factory boost level in the chip (The 
>     boost level on my car is controlled by the computer). I am currently 
>     making my own boost controller, but I can't help but wonder about the 
>     option of modifying my boost level in a reliable electronic method by 
>    such a simple thing as changing the PROM. This would be far cheaper 
>     than any other method I know of (including the standard boost bleed 
>     mechanical method), but would retain reliable/accurate boost levels 
>     achieved by after-market electronic boost controllers as it is 
>     essentially an electrinic boost controller intergrated in the factory 
>     management computer.
     
You can get an aquarium valve and put it inline to your wastegate and dial 
you your boost up for about 15.00 US.  And it would take probably half an 
hour to do.  That is way faster (less challenging) than trying to hack the 
code of the ecu.
     
>     I am not interested in changing fueling parameter currently as I don't 
>     know enough to do this, and could easily damage my engine. Currently I 
>     am only interested in altering the Boost level.
     
Wise decision, playing with your fueling without using a wide range lamda 
sensor is really playing with fire.  In seconds you can melt a piston.
     
>     Before anyone asks, I don't know what type of computer Subaru uses, 
>     but If anyone would car to tell me I would like to know......
     
It is made by JECS. Japan Electronic Controls.  They also supply most Nissan 
ecu's.  Techtom in japan makes all kinds of expensive prom burning stuff that 
will work for your car.  you might try getting a connection to japan, as they 
may already sell an prom for your car.  Then just add a socket to your box 
and away you go.
     
Max