Reprogramming Stock ECM PROM Unit

[Martin Evans]

George_McLaughlin at bedison.com (George McLaughlin) wrote:

> Sorry if this has already been discussed, but I am interested in 
> modifying the stock ECM PROM chip in my 1990 Lotus Esprit SE and 
> am looking for some help.
 
> I would be greatly appreciative therefore if anyone with 
> knowledge in this particular area could provide some pointers or 
> direct me to some references (books, magazines, internet, etc.). 
> I am interested in all aspects of this development from 
> hardware, software, and engineering knowledge needed to 
> reprogram the stock tables.
 
Get the Bosch red and blue handbooks. Read as much as your 
brain can stand <s>; You then have the basics in place. 
Then digest all the archives of DIY EFI.

Assuming you've got the original factory manuals for the car, 
then read the one on the ECM cover to cover a few times and 
try and understand what inputs and outputs your system has 
together with how the control is achieved.

If the system is similar to my Elan, and I believe it is, then 
boost level is controlled by modulating the manifold pressure 
with a solenoid valve to restrict power. The engine has a 
fuel cutout if the preset maximum boost level is exceeded.

The usual way to increase midrange power is to remove 
or reduce the effect of the modulation valve by fitting a 
bleeder valve (cheap and nasty) or by changing the 
wastegate actuator, increasing the fuelling, and 
reprogramming the boost tables (the proper way).

The Esprit post 86 or so and the Elan use a Delco sourced 
ECM. I've bought a spare ECM and pulled the PROM chip on it.
It contains I think both the program code and the tables. 
There is the possibility though that the main processor chip 
has on board memory which is not easily accesible.
I've run my code on a simulator and am in the very early 
stages of seeing what exactly goes on in there. I have a 
different objective to you though in that i'm trying 
to extract the ALDL information.

To sum up, DIY prom mods are not easy, and realistically 
it will take maybe a couple of years for anything like 
an understanding of what is going on in there to be 
achieved. If you want to learn go ahead, if not buy a 
preprogrammed chip from someone with an unblemished 
reputation (very difficult).

Martin Evans