Pauerman

I've been looking very closely at the Autronic SMC stand alone setup and am wanting to use the stock sensor for the TDC reference.

Does the TDC signal come from the reference mark sensor on the bellhousing or somewhere else?

According to the manual there is a TDC test port mounted on the back side of the cam tower - is this tied into the reference mark sensor or some other independant sensor?

Does anyone know what the format or configuration is for the flywheel trigger wheel? (ie - 52 tooth, 60 - 2 tooth, etc..)

Thanks

Pauerman

ANyone????!!!!!!!!!

There's got to be someone out there who knows something!!!!!!!!!!

There seems to be so much talk about going to stand alone systems, so how is it that no one has come across this situation?!?!?!?!!?

All I want to know is where the TDC signal comes from <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Bri Bro

Does the TDC signal come from the reference mark sensor on the bellhousing or somewhere else?

The Reference sensor and the RPM sensor are keyed by the flywheel and sit next to each other on the drivers side, at the back of the engine, in a Al bracket.

According to the manual there is a TDC test port mounted on the back side of the cam tower - is this tied into the reference mark sensor or some other independant sensor?

This is not connected to anything else in the car, it is a test port. Best explaination I have heard is that is connects to a Porsche diagostic computer.

Does anyone know what the format or configuration is for the flywheel trigger wheel? (ie - 52 tooth, 60 - 2 tooth, etc..)

Not sure what you are asking here. Are you wanting to know how many time a sensor is pulsed in 360 degrees or the number of teeth in the flywheel.

Pauerman

Thanks beab951 for your response.
I need to find out if the Autronic SMC has software compatible with the TDC reference sensor on the engine. I was asked to find out about the number of teeth and I'm guessing the number of pulses in 360 degrees of rotation would be helpful

TT

The reference mark is actually set before TDC. For the 944 the mark is 21 teeth (58.15 degrees) before TDC and on the 951 it is 21.5 teeth (58.64 degrees). The number of teeth on the flywheel are 130 for the 944 and 132 for the 951.

Motronic measures timing using the pulse transitions so there are twice as many transitions as teeth. Timing accuracy is 1.38 degrees for the 944 and 1.36 degrees for the 951.

Most aftermarket ecu's use a 60 tooth (crank driven) or 120 tooth (cam driven) wheel and use either a missing or extra tooth to signify TDC. You could probably use a microprocessor with some comparators and a DAC to convert the stock sensors output to something the aftermarket ecu can digest. In the case of the Autronic SMC, if TDC is all that is needed, just trigger off of the reference mark, count 21.5 teeth using the speed sensor, and fire a pulse to the SMC.

IIRC the 944S2 (and the 944S and 968?) uses the missing tooth scheme driven off the flywheel teeth. That would be the most straightforward candidate for use with the other aftermarket systems if the number of teeth can be accomodated.