Algodoo

Definatly one of the weirdest engines (and gearbox) I have ever seen, so maybe that's why it isn't working as it should.

As for the engine, it is the most unlogical engine ever ... but it is working.
Pretty clever to try high and low speed piston movement at the same time, but I doubt if it will work at high speeds/rpm because of the fast moving piston (which might explode or get out of it's cilinder at high speeds).
But you can try a negative damping factor (like -2) and a higher constant to get the engine running. This is the only thing I know about spring engines.