RPM isn't working .. could it be a sensor? or ..

[rAphb0y]

replaced the ecu because due to something my old one burned out .. so all of a sudden the RPM worked for a little .. then it didn't want to work anymore

what could this be ?

[offroader1006]

could be the tach itself.

engine doesn't like to run without the engine speed sensor.

check the ecu terminals for damage.

this link tells you which are used for crank signals

http://www.perfectpower.com/download...C_-_M3.8.5.mht