the elm unit is what we started with as we wernt to sure and belive me It works for diesels weve used them in the past. at £6 it a very cheap entry into obd And yours is obd.compliant.  Without diagnostic support it is going to cost you a lot of money to find this fault. it could be anything from a loose wire to a knackered engine. but anyway here goes   http://www.ehow.com/way_5471047_do-check-crankshaft-position-sensor.html   theres one there for the camshaft aswell.  test them and let us know the results please