Hack and program you own Motronic Chip

[Steve W]

The rev limiter is located at 130h and is equal to the hexdecimal value*40. For example, looking a location 130h in the screenshot of UltraEdit, you will see it reads A3. Hex to decimal conversion of A3 equals 163. 163*40=6520, the rev limit shown on the fuel map. Want to raise the rev limit to 6800? 6800/40=170. Decimal to hex conversion = AA. Change A3 to AA with your hex editor and save.

UltraEdit32 screenshot

[Tyson Schmidt]

Oh great. Just what I need. More ways to play with my car!

Very cool Steve. Thanks for the tip.

And I thought MFI and Webers were fun to tune. This makes it possible without getting dirty and smelling like gas.

[campbellcj]

Wow, that's pretty wild stuff!

What I find similarly interesting, and maybe a bit more "accessible" to those of us who haven't practiced our hexadecimal conversions and assembler programming in a while, is what you can do on the newer OBD-II Motronic cars.

For instance, for $199 I can get the (laptop) interface cable AND software to view and reprogram all kinds of stuff on my S4. http://www.ross-tech.com/vag-com/index.html

Big brother is here! These little computers keep track of all kinds of stuff...

[masraum]

I don't know about the rest of you but I am impressed.
Good job!

[kstar]

Steve:

You need to get together with Mark Hargett. He also fiddles around with simple, mundane tasks as you do.

Mark is working on a "roll your own" "x"-actuated paddle style transmission for his supercharged motor in his 993 look car (the entire car all engineered and all hand assembled by Mark).

Seriously, folks like you and Mark never cease to amaze me - IMO you guys are the Einsteins of 911 performance. It is amazing that a single individual can set out to master skills that once required not only a small team of engineers, but a "factory" to provide support!

Reminds me of the early days of the personal computer. Sheeit, it may take "two guys in a garage" to field the next Porsche Le Mans outright winner.

Although I offer very little to this thread, I applaud you for your work. Very impressive. Time to start thinking about business "arrangements".

Best to you,

Kurt

[dickster]

LOL - steve i'm also impressed

i've got an '86, a laptop, enough spare cash, and love to play with stuff for the hell of it (an inquisitive mind)

have you actually tried it on your car yet?

the dickster

[Natchamp]

OMG, and I thought I was a techno-geek! Very impressive indeed Steve. How did you figure all of that out? Are you a programmer? I have also been playing around recently with electronics and have a project you might be interested in. You should put this together as a package and market it.

[Glasgow 911SC]

I wish I understood. Looks good though!

[JohnC]

god bless you Steve.

Protomotive was selling the same "stuff" ,I think, for $999.00.
http://www.net-quest.com/~knighton/software.htm

Steve, I have a carrera intake manifold complete with injectors and airflow meter.

Question: could i use the Motronic system on a turbocharged engine? Obviously the software would have to sense pressure? Ideas?

[nhromyak]

Where does one get the reader/writer and extra chips?

TIA

[mattd]

It strikes me that it wouldn't be too hard to build a nice graphical front end to perform the re-maps under the covers! Then talk to the eprom writer and you would be in business! Make it open source, and free...all the better!

Matt

[JohnC]

350hp SAAB hehehe.....great stuff....

It looks like I'm going to be keeping my eye open for a motronics brain.

Keep up the good work.

[dickster]

steve - you know about hotwire as well! is that the same as hotfilm?

i'm hoping to upgrade to that (hotfilm) eventually (money!!), sounds like you think its worthwhile.

the system i'm interested in is by amd (uk firm). theirs uses an interface that converts the signals to talk to the cars computer. they also told me that there is no cutting of wires involved, plugs right into std harness.

i'd be real interested in your comments

the dickster

[d_boyce]

Here's how you convert values in the idle, midrange and full-throttle Fuel (lambda) tables to something readable.

Lambda trim = value / 127

[Oldporsche]

Hokay-Hokay

Would a practicle application of this be to backdate an early SC that had CIS with a motronic unit? Thus build the hot rod and still take it to the emission testers at inspection time?

Enquiring minds sometimes ask those that know.

Thanks,
David Duffield

[ChrisBennet]

Originally posted by old_porsche
Hokay-Hokay

Would a practicle application of this be to backdate an early SC that had CIS with a motronic unit? Thus build the hot rod and still take it to the emission testers at inspection time?

Enquiring minds sometimes ask those that know.

Thanks,
David Duffield

While updating to Motronic would make things more tuneable and efficient, the necessity of running a mild cam would still remain. The air meters on both these systems don't like to see pulses coming back up the intake from a more radical cam.
-Chris

[Early_S_Man]

How about adding a bit of code to utilize a knock sensor to retard ignition timing ... or maybe retrofit a 964 DME unit, and make its' fuel timing values programmable for different-sized engines and varying gasoline quality?

[d_boyce]

The fuel tables are actually trim values in lambda. The base injector pulse width is determined by the air meter signal and RPM. In fact the data points (x/y) for the 3d fuel tables are rpm and base injector time.

There are also trims for air and engine temp as well as a host of other things like cranking and warm-up.

Also, there's a really important often over-looked ignition trim based on intake air temp.

-doug

[ChrisBennet]

Originally posted by d_boyce
The fuel tables are actually trim values in lambda. The base injector pulse width is determined by the air meter signal and RPM. In fact the data points (x/y) for the 3d fuel tables are rpm and base injector time.

There are also trims for air and engine temp as well as a host of other things like cranking and warm-up.

Also, there's a really important often over-looked ignition trim based on intake air temp.

-doug

Spill it Doug! How do you know so much about this?
-Chris

[d_boyce]

Originally posted by ChrisBennet

Spill it Doug! How do you know so much about this?
-Chris

Hours and hours of reverse engineering using an 8051 emulator. I turbocharged a 964 which required larger injectors, a pressure sensor and a hot film air meter.


-doug