986 Tach Signal
 

Hi guys,
I'm trying to work out how to make the Boxster tach work with my LS V8 conversion. The new GM engines all use 58X reluctor wheels which are just plug and play with the Porsche tachs, but unfortunately my engine is 24X. The LS1 ecu spits out a 5V square wave at 2 pulses per revolution. Does anyone know what kind of signal is fed into the Porsche tach?

I guess if all else fails I can make some optical arduino tach or maybe do what this guy did on his Lotus swap:

4.2 V8 ABZ conversion of Lotus Esprit :: motorgeek.com

http://i67.photobucket.com/albums/h2...670750x562.jpg

I used the ODB II pin which parallel's the tach input. It is 1 to 1

I'm not going to have a Porsche engine in there, so the OBDII will not have any engine outputs