I neglected to say that the ALDA should be left alone if you want your car to drive as it was designed to for many years. Some time ago I messed with mine but discovered that changing the setting merely covered up other maintenance issues I had to address. I ended up installing a virgin, used ALDA and I stay on top of diesel related tune-up issues and must say these cars run awesome with proper maintenance and care. I love my '83 300D (almost 300k)!