if my ip timing were off far enough to get terrible fuel mileage would there be other symptoms of incorrect timing, like smoking or rough idle. The reason i ask is because i seem to be getting terrible mileage. Been that way since i owned it, a little less than a year. I mean like maybe 15 - 17 on highway while being mindfull of speed 60 - 65 max. New fuel and air filters, rebuilt injectors, diesel or bio-diesel, - no real difference. I feel like i can watch the fuel gauge go down as I drive. There is no fuel leak. No smoking, idles smooth, maybe has less power than others i have driven. any ideas

__________________

1996 E300 110,000
1985 300TD 212,000
1980 300D 238,000