I found an old sound mod that has not been updated since it got taken off repository. So Im updating it to make the sound for the ETK I. I dont know how to make a sound mod though. I know its like this Vehicles>etki>sounds>sound.sbeam --- Post updated --- Edit: What I meant is that there is no sound at all for the ETK I.
The mod was most likely made before the I-series was released and hasn't been updated to include sound files for it.
If you don't know how to make a sound mod check out this tutorial: http://www.beamng.com/threads/tutorial-how-to-change-vehicle-sounds.29193/ And if you still can't figure it out can you upload the file so we can take a look at it?