Menu toggle

944 DME Project

B

barks944

New member
944 DME Project

So I've been working on a DME tuning project for a little while now, I've been doing a lot of researching and planning and I've finally got underway. Anyway the idea for the project is to upgrade the internals of the bosh motronic DME, similar to the Vitesse kit but a bit more extensive. The Motronic DME has two PCB's inside, one for analogue electronics and one for digital. If you have ever changed the chip in your DME, that chip resides on the digital board along with the microprocessor. I intend to build a replacement for this digital board which will feature modern components and entirely new software. This will allow for a host of features not possible with the original DME and will not require any piggyback devices. I will be extracting all the info from the factory DME chip to create a base map. The following are features I hope to implement with this.

1. MAF/MAP
2. USB/Bluetooth programming/datalogging
3. Boost control (Speed/RPM)
4. Closed Loop AFR
5. Using android smartphone as display/datalogger/controller via bluetooth
6. Multiple Fuel/Ignition Maps

I guess the purpose of this thread is to get some help and support for the project as well as some new ideas and suggestions. I'm doing it as much for my own interests as anything, maybe if it turns out well then I might look into making it into a sell-able product. For now however its going to basically be a design prototype for me to mess about with and too see if I can make it work! Anyway here's some pic's that might better illustrate what I'm attempting to do.

IMAG0166.jpg

IMAG0167.jpg

IMAG0168.jpg


The board on top left is the original DME Digital board, top right is the original DME analogue board and harness connector. And the small brown piece of breadboard is my prototype. The prototype will be soldered to the analogue board via the grey ribbon type cables. The prototype hardware isn't far from completion, the software however hasn't been started and it is this that will take the majority of time and effort. Essentially I have to program an entire engine management system, should be fun!
 
It sounds like an interesting project. Unfortunately it is way beyond my understanding. Good luck with it though.

 
Barks, your project sounds fascinating and I would wish you luck with it too.
I am not aware of anyone taking the Original ECU and updating it in this way, everyone seems to work around it with interfaces, conversions and piggyback systems or replace it with stand alone system.
Apart from the job satisfaction, do you see performance benefits beyond whats out there, Vitesse is probably the benchmark from what I hear.
By the way, all my 951's have had Original ECU's with either Promax/SciViz or JMG/SPS upgrades. They have all worked well for me, but my cars tuning is mild compared to some.
keep us all posted with your progress.
George
944T
 
Performance wise I think it comes down to tune, as long as the system can accurately inject fuel and time the ignition the rest comes down to good tuning. The system will be able to map ignition against rpm/air temp/map etc and the MAF/TPS will take care of fuelling. I plan to implement good closed loop boost control that will be able to control boost against RPM and maybe road speed. I think the benefit over something like Vitesse is that its a much more integrated solution and it replaces some of the old components in the DME (not all). If I enjoy doing it and it works I might design a single board to replace both boards in the DME. Essentially its a standalone that plugs into the standard wiring harness and uses most of the standard sensors.

One of the things I really want to do is fit it with bluetooth so I can write an app to go on my android phone and use it as a display for the DME and for tuning.
 
Tom,
nice to see you have had some progress on this. As we discussed about this couple of months ago, i still found this idea the most interesting. Keep up good work, waiting forward to see working prototype [:)]
And we finns expect to have Nokia compatible system.... Actually have few Porsche friends who works with mobile phone development division.
 
Excellent Olli, I can provide details of the serial (over Bluetooth) coms protocols that they would need to build an app. When I've written it anyway :).
 
Yes, whoever came up with that one is a true genius!

http://www.aemelectronics.com/4-channel-twin-fire-ignition-module-671

Can use them with these for CDI too.
 
Tom, how hard would that be to install that "box" to un-modified DME? I checked out the AEM installation manual and tried to figure out what AEM input wires goes to on what DME's ignition out put wires; not much of these after all.
We are looking for at start, a cost effective way to have COP or coil pack system without distributor installed to junior's 951 project [;)]
 
Not without some external unit to distribute the spark. You need a minimum of two ignition outputs to drive wasted spark. The box would need to know engine position so it wouldn't be trivial.
 
yes figured that out, since there is only one output in DME wiring. wonder if there is such a box commercially available. Vitesse had it, but John does not have them in his stock any longer.
 
There may be some generic hardware out there that can be used to convert from distributor to wasted spark. Probably including some kind of crank trigger and sensor.
 
Can you not replace the dizzy with a simple trigger that gives 4 pluses per rev, fixed at massive advance to give the computer time to do the sums and then trigger the correct cylinder based on how many pulses its received since the last crank position pulse?
No need for wasted spark then, but still run plugtop coils for individual cylinders. Could add individual cylinder advance/retard then as well.
Can you see the feature creep ;)

Dave
 
Yes you can certainly install a cam trigger and some kind of external ignition driver and use that to drive COP's.

I'm going to add two ignition outputs to my board so I shouldn't need anything on the camshaft, I'll just drive wasted spark directly from the board outputs.
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top