A good text for many to read is the "Bosch Fuel Injection & Engine Management"
by Charles Probst (SAE member). Also, the Bosch "Automotive Handbook" (3rd edition)
is very informative. For those interested in more recent Porsche technology, the Porsche
DME 7.2 Manual - OBD II (WKD 483921) is another good read.
For those that are DIY types, get an old DME unit and apply power
to pins 18 & 35, ground to pin 17. Then use a sine wave signal generator
to apply a speed signal to pins 8 & 27. Use a differentiated square wave applied
to pins 25 & 26 (ref signal), and you'll have a functioning DME unit to "play" with.
Use this approach to fix your own DME problems.
For those software types, "read" the EPROM as a binary hex file
and save it on your P.C. Then use the MS DOS DeBug program and
you can disassemble (list the 8051 code) it and figure out what
the DME is doing in your 944.
No real mystery to the 944 DME, it's very very simple technology you
might find in a high school electronics class. So let's not over rate
those that appear to be knowledgeable about the DME operation.
The 996's technololgy with OBDII and the immoblizer gets a little
Bottomline: The 944 DME design is over 20 years old now and many
(like lots) have "hacked" it. So there ain't any real 944 DME gurus,
just some who think they are, as is obvious from this forum.
wow, your irrogant. Makes me want to use your services.
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89 944 Turbo S
86 944t Track only
This uses an idle switch & WOT switch and a TPS combined into one unit.
The outputs from these go to the DME pins 2 & 3, respectively. The TPS
outputs go to the KLR pins 21, 22, 23.
Bottomline: The DME has a switch inputs element and the KLR has a true TPS input,
i.e. a varying voltage input
Now I know this is wrong.
There is only an idle switch and NO WOT switch in the 944 turbo TPS(Throttle position sensor)
The WOT Signal is derived from an output from the KLR and sent to the DME to "signal" Full throttle.
On a side note... I have wondered if the "click at idle" adjustment is really the best way to set. It really depends on whether the KLR is using the throttle position sensor as a true indicator of throttle plate position OR, as I suspect, only an indication of the 'rate of change' to 'Drive' a WOT signal for the DME.
On cars where the TPS signal is used in fuel/timing calculations then idle position is set by adjusting the sensor to a given voltage at idle.
But the 944 TURBO only has an idle switch and a Pot , No WOT switch.
Lorenfb. Have you successfully tried to load and disassemble a Motronic image this way?
1382:0000 0202 ADD AL,[BP+SI]
1382:0002 4E DEC SI
1382:0003 C28B21 RET 218B
1382:0006 F0 LOCK
1382:0007 FFFF ??? DI
1382:0009 FFFF ??? DI
1382:000B D290C20A RCL BYTE PTR [BX+SI+0AC2],CL
MSDOS debug is an 8086 disassembler/debugging tool, not an 8051 tool.
The first instruction 02024E is 'ljmp 024Eh', not an add op-code.
TT is dead on, the 8751 op codes and internal structure are entirely different then the 8086. The 8751 is an 8 bit controller with built in I/O, Ram, Serial Ports,Timers and ROM. The 8086 is a 16 bit processor and doesn’t have support functions built in like the 8751 does. And as a preemptive defense, I have built/programmed the 8751 on many occasions in the past. This series of micro processor (MSC51) is still being used, but is getting very dated. Anyone want to pore through hundreds of pages of spec sheets comparing the two, here is the link. http://www.datasheetarchive.com/datasheet/pdf/4332.html
And after all is said and done, the TPS does click. I would go nut if everybody started calling components by the Porsche manual names. The manual are translated from German and some of the names are just nuts!
"Andrew: I don't want to start anything and don't quote me just yet, but i do recall seeing the 951 throttle switch operation. If memory serves correctly, it has idle, cruise and WOT switches." - hosrom_951 -
And for the others, stop guessing! Please read page 19 of the 944 Turbo manual (WKD 453 920).
MS DOS DeBug obviously is NOT the most appropriate assembler to
use, but it is simple and allows code mods, e.g. timing & fuel, and a
BASIC overview of the u-code of a DME.
The resistance values stated are the 'range' from idle to WFO...not a 'switching point'
When you check a TPS with an analog ohm meter you will , or should, get a smooth resistance
increase from idle to full open that falls in the range of the factory specs.
This does not mean that there is a full throttle 'switch' or point...just that a 'good' TPS will fall within this range.
Other than that, the diagrams are simular...I just think you are interpreting the info a little wrong.
BTW, I'm no expert on Bosch...just a military trained avionics tech and an automotive mfg engineer.