I have the same problem as the guy further down the threads. My 79 300sd runs fine, starts fine, and has good accelleration.
I have only had the car for a few weeks and my first full tank fill up showed 20.8 mpg. I was crushed. I thought I would have to really lead foot it to get below 25.
The air filter is clean and the previous owner had set the valves within a year. The car did a lot of sitting during his ownership. I dont know if this could be a factor but I burned most of the old fuel before my first fill up. He is pretty mechanical so i assume he set the valves properly.
Someone in the other thread mentioned the EGR valve and the possiblity of disabling it to increase mileage. I would like to hear more about this. How is it done? The possible negatives? What does it do anyway? Will this turn me into a soot spewing eco terrorist?
Thanks
Eric z