Building a Porsche 3,0l 944 turbo
Now the details that affect VEMS specs and installation.
- original Bosch Motronic sensors will be used
- water temp x2 , oil press, knock
- exceptions are MAT and MAP, these will be from VEMS web shop
- original wiring loom will be used
- fuel injectors are SiemensDeka
- Static Flow Rate (GAS): 86 lb/hr @ 43.5PSI (300kPa) = 903cc/min, 10.88g/s
- Coil Resistance: 2.35 Ohms / Low Impedance / Low-Z
- Ignition for starters wasted spark, with option to COP
- TPS will most likely be the one that comes with ITBs
- For trigger see below
Trigger
primary (crank)
* toothcount ?
- missing tooth ?
- VR / HALL ? Anyone knows this ? 'Both are VR' PPaadam
Porsche 944 turbo Trigger: 132teeth on flywheel, VR sensor and Crank home (1 pin on flywheel 58,5 dec BTD, if i remember right) VR sensor. No cam sensor) And no missing teeth!
Are You doing Plug and Play to motronic harness? Same project. Yes.
secondary (cam)
* VR / HALL ? Anyone knows this ?
There are doubts that both of them are VR, so investigation is needed.
For both sensor, measure all pairs of pins, in both direction (with a 3 pin connector this is 3*2=6 measurements). Write them here.
OK, what I now know is this. Info above about flyweel teeth count, pin on flywheel and sensors type are correct, that pin position has just to be confirmed. I bought yesterday a book "Bosch Fuel Injection & Engine Management" and it describes this system
" For the most accurate measure of engine timing and speed, Motronic systems read the position of the crankshaft directly. Special sensors pick up signals from the flywheel teeth."
"The rpm sensor ( also called the engine speed sensor ) is an inductive-pulse sender that picks up pulses from a toothed wheel, usually the flywheel. The rpm signal can be displayed on a scope just as it is sent to the control unit, one blip or spike for each tooth. It is so accurate it can sense an rpm chance while the crankshaft turns only a few degrees.
The TDC, or reference mark sensor ( reference from cylinder no1 TDC ),is triggered by a set screw on the flywheel. each time the srew passes the TDC sensor, the sensor signals one blip for each crankshaft revolution. Both ensors are magnetic, with a soft iron core that stores the magnetic field. When a tooth in the flywheel or the reference sensorpin moves though the magnetic field, the change induces an electrical voltage in the winding. This voltage is he input signal to the control unit. The sensor is known as a passive diffusionfield sensor, because it does not require a current supply."
I have these both new sensors, identical, at home, I will post their Bosch number here as I return home. I guess this makes the system what is called the Auditrigger.
Trigger measurement: If you have those Vr triggers on table, is it possible for you to measure the polarity of them? As you know they are quite difficult to get access while the engine is on car.
Measuring trigger Vr trigger polarity.
measure with DVM, 200mV DC mode. If your wheel has normal shape (missing tooth), than signel should be +few mV when you move ferrous metal (iron) towards the sensor, and -few mV when you move it away. The reading shows up for a very short time only (while the sensor actually sees the movement)
Shopping list
Assembled v3.3 controller
- 1-wire interface no
- ignition driver 4
- Knock and EGT yes
- LCD and PS2 yes
- MAP connection 400kPa onboard (5/3mm pneumatic) 'I'd recommend 6/4mm connection' PPaadam
- mounting-style screws
- PowerFlyback yes
- primary_trigger VR
- secondary_trigger VR ''Should be "auditrigger"' PPaadam
- EconoSeal36-Wire
- Econoseal18-Wire
- EGT sensor (K-type) Size 2mm
- K-thermocouple connector
- mounting-style panel-mount
- Sex pair
- mounting-style flyback
- Sex pair
- Wideband O2 sensor
- Wideband connector
- With wire with crimped wires
- MAT sensor
- Pneumatic valve 3way
Update on the 29th of April.
While being busy with engine's installation I also did the wiring harness, modifying the old one for VEMS. I removed unnnecessary parts, reused some wires with new tasks and build completely new harness for fuel injction and ignition. I also replaced DME & KLR harness connectors with Econoseals and integrated Apexi AVC-R to this harness. I attached the VEMS box to the original installation plate at passenger's footwell. There was so much space that I managed to place fuses and AVC-R's own MAP sensor there. There's still some pins/wires unconnected ( see questions below ) and some finishing work to be done, but I thing that I can start configuring my system next week.
Unfortunately all my pictures are at the moment at page that needs password, but I try to change that later.
Questions with new ones
How shift light output is done? It is done using rpm triggered outputs
Any specific info on this one...eg. which pin? ...although I have now read the instruction manual and have some clue about this myself...
I want the original boost gauge in instrument panel to be functional. The problem here is that it is electronic, ie. the Motronic's KLR ( boost & knock control unit ) feeds it. So it needs output from Genboard. Other peoples obsevations how the signal is handled can be found here
http://forums.rennlist.com/rennforums/showthread.php?t=313463&page=2&pp=5&highlight=boost+signal
Is it possible to get such output, and scale it a bit differently? Now the gauge shows 1,0 when MAP is athmospheric, and I would like it to mean 1,0bar boost... Does anyone have anything on this, like proper pin number and possible configuration data...??
Related to previous question, how can I get rpm signal out of the VEMS? 12V or 5V logic level pin and how to configure it ??
More questions
Do I need PowerFlyback when using low-impedance injectors?? Yes, definitely
I managed to screw my order at this part and didn't get the bidirectional transient supression diode with my othre stuff. Instead of 30V I got 39V one from local electronics shop. Is it OK to use it?