I am reaching out to any ECU tuning experts on Rennlist, looking for some help in locating a couple of data points in the Motronic ECU EPROM so I can make a slight adjustment.

I have owned my 964 since 2001 and installed the Autothority MAF setup around 2006. I have been happy enough with it to keep it installed, always enjoying the growl I hear when the secondary plenum opens up at around 5K rpm which never fails to put a smile on my face! The one thing that I do not like about the MAF chip that came with the Autothority MAF is that they raised the Rev Limit to (I think) 7000 rpm which, even though I try to stay away from the redline, makes me nervous about exceeding Porsche's well considered limit on this. The Idle rpm is also raised to 1100 rpm, which I can live with, but would like to lower a bit as well if that doesn't cause a stalling problem.

I am a retired EE (obviously with time on my hands) and have the tools to read/modify/burn DME ROM chips. My problem is, even using the tools that I have (including Marc Skarshinski's Motronic Editor) I don't have the skills to locate the Rev Limit or Idle rpm setting locations in the Porsche (964618124-03_1267357006) or Autothority ROMs. I am hoping that someone on the forum might be able to point me in the right direction on the location of these values in the Autothority ROM so that I can adjust them slightly. Any educational tips regarding the interaction of these settings with other data (i.e. Fuel or Timing maps) that might come along with this info would also be appreciated!

I have attached the .bin files for reference.

Thanks in advance!

Jim G.

 

Just for fun, I downloaded your two binary files to see what I could figure out. I ended up using AI to scan the binaries and extract the different maps. It's still a work in progress, but I see that most of the differences in the AuthorityMAF tune is in the correction tables.

I need to have it iterate on the binaries or possibly source some more ROM dumps to refine where it is looking up values. I'll keep messing with this to see what I can get. I'll try and add some editing abilities in my little tool.

Here's the repo, if you are curious: https://github.com/tosih/motronic-m21-tool

Sohail

 

Thanks for that Sohail, but as Dirty Harry once said "A man's gotta know his limitations". My software education started with Fortran punch cards on an IBM 360 mainframe and has very gradually progressed to a basic working knowledge of C++ on my Arduino hobby projects. Let's just say that when it comes to modern programming environments I have a reasonable understanding of the concepts but the details are beyond me. When I look at your GitHub motronic-m21-tool I'm not quite sure where to start!

That's exactly where I am with the Motronic. I know what it does and basically how it does it but don't have the skills to make much progress digging into the bits. Using Marc Skarshinski's Motronic Editor I can sort of recognize timing and fuel tables but it has no built in capability to identify the Idle or Rev Limit values. I will keep looking at it and also keep trying to contact some of the tuners who were involved with the Porsche ECUs in the past.

Cheers!

Jim

 

It's just all about increasing the ignition timing! Modifying the fuel maps without more air intake, e.g. supercharing/turbo, gains nothing. Read here;

http://forums.pelicanparts.com/porsc...ning-myth.html

How various "tuners" push the timing beyond stock:

https://www.systemsc.com/tests.htm

 

Loren,

That was the logic that made the most sense to me for the Autothority MAF. I reasoned that the switch from the stock barn door air AFM to the open flow MAF sensor intake would provide some slight improvement in airflow, which would (slightly) improve overall performance. The fact that chip tuners typically get their gains by advancing the timing didn't sit particularly well with me since it comes with the increased potential for ping/knock. I offset this as much as I could by switching exclusively to 94 octane fuel which helped significantly.

The other half of the story of why I went for the Autothority MAF was that I got it at a bargain price from a fellow Rennlister. He told me that he was selling it because he was bumped up two groups in the Club Racing points grading by having the chip and MAF intake on his car, so he decided it wasn't worth it!

The bottom line, as I mentioned at the outset, is the little voice in my head that really wants to get the rev limit back to stock where the Porsche engineers thought it needed to be for optimum engine longevity.

Cheers!

Jim

 

With regard to tweaking the ignition timing, the knock control in the 964 DME ECU retards the timing up to 9 degrees when cylinder knocks occur for each cylinder.
So when "tuning", less HP may result under various driving conditions, e.g. climbing a mountain grade on a hot day with an unknown octane!

 

OK, I'm going to bump this in case anyone missed it the first time. If you know the "gritty details" of the 964 Motronic ECU or know the contact info for someone who does, please reply or send me a PM.

Still looking for hints on the location and modification implications for the Rev Limit and Idle RPM settings in the Stock ECU ROM and/or the Autothority MAF ROM.

Cheers!

Jim ​​​​​​​

 

Jim, I don't have any info for you but please share what you learn. For example, do you have a link for the Motronic file editor that you mentioned? Thanks!
​​​​​​​

 

I found a download of the MotronicEditorV2 program on one of Mark's posts here. Look at comment #12 for the download. I didn't re-download it myself as I already have it installed so I can't vouch for this version personally.

Jim

 

Hi there
Found this post interesting in my case so jumping in ( to ask question, sorry not to bring more answer )
Can our Motronic be adjusted on injector deadtime ( see https://support.haltech.com/portal/e...ctor-dead-time ) and voltage compensation table when fitting different injectors?
My tuner says no, only fuel and ignition maps, but we have issues to tune idle and low load and car has been fitted with 993 injectors
I run an early version of the ECU 0261200182, / TYP 911 MW-DZ-01

Thank you!

 

If you change injectors, you would absolutely need to change things in the calibration such as the injector flowrate, voltage compensation, pulsewidth, etc. You may be able to make those injectors "work" but it would technically not be correct or run optimally unless you can change those things. This would normally be something you do on a standalone ecu.

 

Thanks for replying
I understand the theory but technically without fully programmable ECU ( just remapping the EEPROM of MOTRONIC ) can these values be tuned?

 

You do understand that the 964 DME ECM has sequential injection - each injector is controlled (timed) independently & can be completed shutdown, right?
Hopefully, you also know that the 964 DME ECM has knock control, so when your "tuner" increases the ignition timing advance for so-called "performance improvement",
the knock control Motorola processor will retard the spark timing when detonation occurs - resulting in less torque. Read this link;
http://forums.pelicanparts.com/porsc...ning-myth.html

Maybe time for a new "tuner".

 

If you are trying to get into the level of tuning where you need to adjust for new injectors and such, you should be on a standalone ECU. Lots of options out there. The factory 35+ year old Motronic ECU is just simply quite archaic.

 

You are aware that some are capable of disassembling the DME ECM source code and modifying it in assembly language?
There are also Intel compilers available.