MembersPage/PeteKrgr (2007-02-11 09:33:33)

Building a Porsche 3,0l 944 turbo

Now the details that affect VEMS specs and installation.


Trigger

primary (crank)

* toothcount ?

  • missing tooth ?

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


Questions

How shift light output is done? It is done using rpm triggered outputs

Is it possible to do two-level boost control, where boost level is changed by push-button?

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. Oher 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...

More questions

Do I need PowerFlyback when using low-impedance injectors?? Yes, definitely