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#1
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Poor Fuel Economy .. 99 E300
Well, I guess the title says it all.
99E300, 156K on her .. and the fuel economy is almost always 25 mpg, all highway. My assuption was she'd get at least low 30's highway. Yes, the car is new to me (though I had an 83 300SD and am my second TDI). Starts well - regardless of temperature, the power is always on tap. The MAF was replaced - had a CEL for it, a few other odds and ends (air filter, etc. Basic maintenance stuff) A lot of smoke during strong accelleration. My first thought is she's dumping excess fuel into the cylinders, but how? Where shall I look first? |
#2
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First look at a new fuel filter - that'll have a lot to do with bad mpg. Tire pressure while you're at it.
Smoke during acceleration (black smoke) is okay - A LOT of smoke could mean air filter (did you replace it?), another issue that I'm not aware of, or it's just the way your particular car is.
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- Brian 1989 500SEL Euro 1966 250SE Cabriolet 1958 BMW Isetta 600 |
#3
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I had the exact same problem on my 98 E300 as you and here is how I improved my economy from 28mpg to 34mpg:
http://www.peachparts.com/shopforum/showthread.php?t=145076&highlight=fuel Good luck. Scott
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Scott 1982 Mercedes 240D, 4 speed, 275,000 1988 Porsche 944 Turbo S (70,000) 1987 Porsche 911 Coupe 109,000 (sold) 1998 Mercedes E300 TurboDiesel 147,000 (sold) 1985 Mercedes 300D 227,000 (totaled by inattentive driver with no insurance!) 1997 Mercedes E300 Diesel 236,000 (sold) 1995 Ducati 900SS (sold) 1987 VW Jetta GLI 157,000 (sold) 1986 Camaro 125,000 (sold - P.O.S.) 1977 Corvette L82 125,000 (sold) 1965 Pontiac GTO 15,000 restored (sold) |
#4
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Now that I have had my '98 for two full years I can say that fuel economy always suffers in the cold weather. Check the air and fuel filters but don't be surprised if in spring you start to see economy closer to 30 around town and 34 on the highway. I routinely see fluctuations on the order of 10-15% on MPG and it is always lower in the cold...probably a combination of winter blend fuel and lower effeciency of the engines in the cold weather.
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Marty D. 2013 C300 4Matic 1984 BMW 733i 2013 Lincoln MKz ![]() |
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