.... & Chips
Eprom Burner
From: Greg Powzun
Hi Eddy,
welcome back matey. It's been a while, but we still miss your
technical input.
As for the EPROM in the 928, I think it's a 27C256,
dual-in-line package. This type of EPROM is like your common garden variety
and is used in heaps of electronic gear (I have a draw full of them at work
for the fibre-optic terminal gear). Being a CMOS device, you'll want to make
sure that the programmer is compatible not only with the device model, but
the manufacturer as well as some manufacturers use a slightly different
programming voltage to others even when the device model is the same. I will
try and find out for sure.
Great to have you back!
Greg 9ine2eight Dankelblau
From: "Adrian 007"
Subject: RE: [landshark]
Eprom Burner
Guys
A lot of work has been done on chip grades/comparisons
by fellow US sharksters.
Bottom line was as follows:
- benefits of reprogramming will depend on the year of
your car & spec. eg if you have a 1989 Euro spec GT without a catalyst,
you are probably wasting your time - However you can get 10-15bhp more from
a 1990 s4. There is a company in the US called Authority I think which sells
upgraded chips for about US$500.
- easiest benefit/$ is to change the rear silencer &
(if local regulations allow) replace the catalyst with a performance
version/normal exhaust. This will impact other parts of the rev range
though. Porsche did actually offer a 928 'Sport' stainless steel rear
exhaust (without baffles!) as part of their 'Tequipment' range in the early
1990's. I picked up one a few years ago, but you will be lucky to get hold
of one now (basically it looks more like a mortar launcher!)
If anyone needs any more info on the above, please let me
know.
Regards, Adrian
From: Eddy Sain
Subject: Re: [landshark] Eprom Burner
Adrian,
I followed up some of the US guys and got information from
knowledgeable US users of lots of chips including Authority. Lots of these
users sent the chips back ( 30 day satisfaction guarantee in a lot of cases)
the end result was as I said sometimes felt like it went harder but when
checked on an accurate dyno back to back before and after not worth the
money. On 90 and later cars (maybe even before) you need two chips one for
fuel one for spark the US guys believe that custom chips for your individual
car are worth the effort. OK you can
replace the whole computer with
lots of good units on the market but you need to "bastardise" the
car wiring etc. etc. and then you need to set it up for your individual car
anyway.
I agree a good quick cheap way to get a few free Hp is the
exhaust especially the muffler and even the air cleaner element but there is
more available in the brain with out going into the motor or good old
Nitrous Oxide.
Regards, Eddy
Subject: [landshark] S4+GTS = 27C256 Chip
From: "Greg Powzun"
Eddy,
found that site I remembered. It's at http://www.eproms.net
These French guys have 4 chips. two (identical checksum?)
are for 928 S4, and two are for a 928 5.4 (GTS). The interesting part is
that they detail the chip used for these models. They are: "E
DIL27C256" chips. Therefore we could reasonably say that your
programmer is suitable.
Darren, it is also possible that the instruction code is
stored either on the processor (therefore it is strictly a microcomputer) or
on a PROM chip elsewhere, in which case you would conclude that the EPROM
chip then only contains operating parameters. In the case of two chips, it
is plausable that one is program and one is data.
Greg 9ine2eight Dankelblau
Subject: [landshark] Re: S4+GTS = 27C256 Chip
From:
Sterling Gee
Chips for 928's come in sets. One for each computer. One
for ignition mapping, and the other for fuel mapping. I forget which one is
which. I actaully made copies of a factory chip with a $30 chipreader and
some blank chips, from the local electronics shop. I took the factory chips
in, and they found suitable matches. The two chips are different
specifications. The chip reader created a dos file for each chip, and I put
in the new chips and wrote to them.....
I also tested them and
they worked. I did this for backup reasons and was trying to reverse
engineer them for my project.
This was 2+ years ago, and I decided the gains were
minimal. On a stock car, the gains to be made by chips are minimal. The more
modifications, the more gain possible by remapping the chips. The computers
extrapolate operating parameters from sensors in the car, ie temp, timing,
and airflow, and reference the table for the injector firing.
What is interesting, is that the computer can change the
timing on the injectors, not the pulse width. Certain parameters like the
injector impedance and flow are not adjustable. This is why some people have
worked around this limitation with stroker engines, and just put in larger
injectors. It is an interesting topic though.
The best tuning device is the Dastek product, providing
you stay with the factory computers. If you were to say, go with a MoTeC,
you could realistically gain 25 hp on a stock engine.
Sterling
From: Greg Powzun
Hi Eddy,
The task you have set yourself is by no means a small
feat. For you to be successful, you will need access to some major
information. I will briefly outline what I think you will have to do, not to
discourage you, but to make you aware of the mountain you must climb. You
already may know most of this so excuse me for painting your task as
daunting.
The engine management system as a module is responsible
for taking sensor readings, interpreting them and making adjustments to
optimise the balance between power, emissions and economy. At the heart of
the module is a microprocessor, microcomputer or PIC (depending on the car).
The microprocessor is no magical device, it is simply an Algorithmic State
Machine. It can only follow very very simple instructions (machine code or
assembler code). Each instruction is made up of microinstructions that are
carried out internal to the processor. For ease of understanding and use,
programmers use a higher level language such as C in which each command is
made up of a huge collection of machine code.
Okay now what is on the EPROM is just machine code in
binary form. The code details to the processor what processor instruction it
must carry out and with what parameters. The original designer would have
started at the highest level with something like a flow chart (unless he
used Object Orientated Programming, but I doubt it). From the flowchart, he
writes the program in C. Then an assembler (a program dedicated to that
processor) converts the high level C code to machine code (binary) which is
then burnt onto the EPROM.
Your first step would be to determine what processor is
being used. Being about the ten year vintage, I imagine a commercially
available processor like a 6800 series. For newer cars, a custom processor
is more likely. At Uni, I managed to design my own dedicated microprocessor
using one of the new Large Scale Programmable Algorithmic Logic chips. With
the processor type, you can obtain the full instruction set. They are
usually about 120 instructions.
BTW, this is called reverse engineering. Then you take
your EPROM, put it into your EPROM reader and extract all the binary
information. There will be 256,000 ones and zeros (arranged in 32,000 words
of 8 bits each) in a 27C256 chip. Each instruction is made up of 1 to 4
words (generally), so we're looking at about 10,000 instructions. There are
programs called disassembles that make good attempts at converting the
machine code back to the discrete instructions, but from experience, unless
you have a good one, it can end up being a mess. For example, a data value
may have the same sequence as an instruction, which confuses the hell out of
them. Assuming you convert the binary code back to 10,000 microprocessor
instructions and data, it is nearly impossible to convert the assembly code
back to an understandable high level code. You will grow old trying to plot
out a flow chart using just the machine code.
Lets look at it from another perspective. Having two cars
with the same engine but differing performance is a great plus. Take for
example the S4 and the GT. IF and I stress IF they both used the same
program, then a comparison between their EPROMs would show differences only
in the parameter values (buried in the machine code). These values may be
timing of ignition and injector on-times etc. The parameters you want to
experiment with.
Simply take one differing parameter at a time and take
it to an extreme to determine what it does (maybe to the determent of
the development engine). With the after market engine management
computers, they come with programs that access and alter any of the
parameters at their known locations. These guys know where the values are
because they wrote or have access to the original high level program
(called source code). If, however, you could get the original source code,
then we can do the assembly ourselves, but where could you get that
top-secret information.
As for the programmer you detailed, although it didn't
directly detail a 27C256, I think it would take them and notice the
ability to input the vendor ... very important. Should do the job, but don't
pay too much for it.
Also, you should confirm the chip is a 27C256. I seem to
recall reading it somewhere on the net, an aftermarket chip place, but I
can't remember just where. I will look again soon.
Eddy, when you finish this project, maybe we can put our
heads together and try and crack the Human DNA code. It's only 30,000
something's long ;-)
Greg 9ine2eight Dankelblau
Subject: Re: [landshark] EPROMs what I think happens
From: Eddy Sain
Greg,
I knew most of the stuff you mentioned in your email but
boy I could not have expressed it so well.
What you are saying is correct but there are some existing
programs that do a lot of the work already available I found a heap of sites
in the past and some more tonight
The source codes are available off the net. With regard to
the programming all that I am trying to do is to rewrite the look up table
for the base program not rewriting the whole thing so by modifying the look
up table we change the parameters and hence the characteristics.
I still need to get the chip manufacturer and number but
am reluctant to pull apart my ECU units until I have a spare. I can probably
borrow GT ECU units so i may start from there.
Check out the following link and the other links under
chips and the sample software that you can download I haven't tried anything
yet as this is a long term project and I need to learn before I crawl let
alone walk or run still good stuff to get your head around and if others do
it why not me.
http://www.amitron.ru/opel/NELinks.htm
http://www.bonnevillemotorwerks.com/products.html#chips
http://www.evc.de/en/
DNA code can we engineer more horsepower into it?
Regards, Eddy
From: Greg Powzun
Eddy,
one of your links goes to this mob in Melbourne:
http://www.powerchip.com.au/chips/index.asp?make=Porsche
They say
928 GT 89-91 5.0L uses 2 plug-in pull-out chips
928 GTS
92-95 5.4L uses 2 plug-in pull-out chips
928 S 80-84 4.7L uses a soldered chip
928 S 85 4.7L uses a soldered chip
928 S 86 5.0L uses a soldered chip
928 S4 87-91 5.0L uses 2 plug-in
pull-out chips
But no-ones giving away what they are.
Greg 9ine2eight Dankelblau
Subject: [landshark] Chips etc
From:
"Pitman"
I have opened and chipped a hot wire late Bosch (but
badged Lucas) ECU in a
Discovery, and I suspect the mods are only to
data tables. The replacement chip needed to be matched to the 'family' of
the surrounding chips (several bigger ones) based on codes on one of them.
Most of the rest of the ECU is A->D and D->A hardware I think
(analogue to digital and back again).
You cant learn a lot from looking at much of the hardware
here, but you can in a flapper type air flow meter- there are only 6 or so
steps in these units, based on a few I have opened, so there is no
continuous smooth curve of signal to the ECU for air flow - just 6 or so
discrete values.
On Bosch EFI, the throttle pot sends a continuously
varying voltage, but on Mazda eg, the throttle pot only sends fully shut, or
not, and maybe fully open. From some reading I have done it seems the Bosch
EFI controls fuel delivery by changing pulse length of the injector opening,
which means that at 6000rpm, you only have 10msec of open available to you
and you can end up with continuously open injectors - time for larger
capacity units, with less open time required.
Also, I have found that output on this LR system can be
improved by checking the static volts at the throttle pot are in spec - move
it on its screws, and that of the air flow meter - which has an adjustment
screw in the top side, under a tamper proof cover.
I suspect for most non racing uses, more power can be had
by normal improvements to inlet, exhaust, and advancing timing to just below
pinging.
EG, MX5s , normally timed at 10 BTDC, will run as high as
18 BTDC. Advancing timing 2 to 4 degrees was part of the chipping
instructions on the Discovery kit. If it ain't pinging, it cant do much
harm?
FWIW,
John Pitman
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