93 300d poor gas consumption - PeachParts Mercedes-Benz Forum

duresmith · #1 08-16-2006, 12:20 PM

My 93 300d is getting about 23 to 24 miles to the gallon. I was expecting to get around 30. I have had the car for about 3 months now. I have replaced all filters and fluids in the car. Replumbed the vacume lines - many were missing or incorrectly connected. The car is sluggish until about 20 mph when it takes off.
Tire pressures are correct.

What are my next steps in getting this car to be more fuel efficient?

Thanks
Mark

Also does anyone have some good pics of the engine compartment of a 93 300D so I can see how all the vacume lines are supposed to be physically routed?

Hatterasguy · #2 08-16-2006, 01:01 PM

What kind of driving have you been doing?

duresmith · #3 08-16-2006, 01:42 PM

City/suburbia driving, though I did a 5 hour road trip up to the Sierras (mountains) and it was a bit better, but around the same mpg.

Hatterasguy · #4 08-16-2006, 02:15 PM

I get less with the SDL around town, 21-22.5mpg.

Don't expect more then mid 20's with around town driving. Your off a bit but not by that much. If you let it shift at a little lower rpm you would probably gain a bit.

I assume you already checked the simple stuff like stuck brakes, tire pressure, and filters?

2.5Turbo · #5 08-16-2006, 02:30 PM

You should expect to average 30mpg. I do, and I don't drive like an old granny either

Something's wrong. Check the simple stuff like Hatterasguy recommended. Have you checked for fuel leaks? Little leaks will decrease your mileage. I could have sworn my mileage went up once I replaced my leaking injector return lines.

To adress the sluggishness issue, clean out the lines and fittings to your ALDA. But first of all, drive the car with the hose off of the intake manifold, and check if it's even slower. If it is, then that's not your problem. If not, clean 'er out!

Here's a vacuum diagram PDF for MB diesels of the early 90's. Go to page 24.