If you do plan on selling this, I strongly urge you to include a programmatic interface for collecting the data. I would very much like to integrate information like this into a data logging system I'm developing as a personal project and would hate to have to re-invent the wheel.

 

Man, you get duty cycle, O2 voltage, and data logging on it, and I will be more than happy to purchase a kit from you. That is most excellent!

Great work!

 

Is O2-sensor voltage available? With microcontrollers being accurate down to 1mV or so, you can actually draw an graph of the 0.80-0.95v range that would be really help in tuning air-fuel ratios. That range is typically encompased by a single LED on those air-fuel monitors, so they are tough to use.

GOOD JOB !!!

 

I'd also be interested in purchasing a kit. Keep us all in updated here......

 

[quote] Are you going to share the wealth or are you going to sell it??? <hr></blockquote>

I'm currently exploring my options at this point. I have already laid out an interface board, id'd the components and am looking at packaging. The big item is the code mod for the chips. I could provide the chips modded for stock setups, but would have to individually provide mods for aftermarket chips. Some of the calculations shown are based upon the stock configuration VAF and injectors. Any change to those items would need to be addressed to adjust the values accordingly.

[quote] Also how much more information aside from injector timing can you get from the DME and where are you getting the water temp from??? <hr></blockquote>

The ones mentioned so far are the most useful items. Other items are the O2 based fuel adjustment, accel enrichment, accel/decel advance, cold start enrichment, and warm start enrichment. The water temp comes from the water temp sensor for the DME (there are two in these cars). The temp sensors are not very accurate at the far ends of their measurement ranges, but not too off in the middle.

[quote] If you do plan on selling this, I strongly urge you to include a programmatic interface for collecting the data. <hr></blockquote>

Wrapping it up into a DLL usable by anyone is doable.

As far as O2 voltage goes, Motronic only looks at O2 sensor data as binary. Once in the DME, the voltage goes into an inverting trigger and you get a high for lean conditions and low for rich conditions.

Here at TT's advanced R&D lab, I am looking into using the wide band O2 setup from the DYI EFI site and getting it to work with the stock DME.

 

I would really like a kit as well when its complete you could definately sell some kits

 

what about error codes from the DME?

 

[quote] what about error codes from the DME? <hr></blockquote>

The 944/951 version of Motronic is extremely simple. It does not check for errors and none are output. On the 951, the KLR is responsible for the flashing code output.

 

I am also intrigued, although I suspect a kit would be out of my price league... 'specially right about now... still...

'Hey Thaddeus-- what's that laptop doing on the passenger seat?'...

 

TT,
Great piece of work!

Where did you get the info on how to program the DME? Trial and error?

Do you have a processor on the embedded system or is it not a DSP? Just wondering if you could plug the DME output straight into a serial port and do all the conversions in the software? Would any commersially available embedded systems (Amacron, Synergy, with serial ports on them) work?

Depending on the price, I would buy a kit as well.

 

[quote]Originally posted by TT:
<strong>

The 944/951 version of Motronic is extremely simple. It does not check for errors and none are output. On the 951, the KLR is responsible for the flashing code output.</strong><hr></blockquote>

Skip at Paragon...says for 300 US he can get me a code reader from Porsche that will work on the the 89 year... The connector is just above the DME.. am I wrong that the error codes are coming from the DME?

 

Why do all that when a $.10 LED from Radio Shack will give you a blink code from the connector in the engine bay?

 

Is the data logging internal or external? IOW are you developing something that will store data for later download or must it be downloaded realtime?

I think this would be useful for a racecar if the data is stored for later download.

 

[quote]Originally posted by Perry 951:
<strong>Why do all that when a $.10 LED from Radio Shack will give you a blink code from the connector in the engine bay?</strong><hr></blockquote>

The S2 has no connector in the bay...only the 951

 

What? I could have swore that the S2 had that 4 pin plug as well. Humm... there must be an easy and cheap way to get a blink code out of it.