Realistic MPG in 300D's, 300SD's, 190 D's? - Page 10 - PeachParts Mercedes-Benz Forum

Doktor Bert · #**136** 07-09-2013, 12:41 PM

Quote:

Originally Posted by Willie B

When I got my first Benz diesel The seller told me it got 38... ...I didn't believe him but I checked it and it got 38...1979 300SD 150K miles... ...One night in perfect atmospheric conditions it got 43 @ 3200rpm...A Merz guy in town told me it must have the smaller injectors in it out of a ???...

...I bought another 300SD that the odometer shows 764K miles(not believed to be accurate)...a beater... ...The best I've gotten with it is 25 -28...

...Because of the mountains I live in,...years later both cars seem to be getting 23-25???...

...The odometer in a 1987 300D 6cyl I have,...is broken so I don't know what it gets...The previous owner said it got 28 hwy...

...My '97 Dodge Ram 4X4 xtracab Cummins with 4:10 gears will average 15... ...It has gotten as high as 17.5... ...With an 11ft Lance Camper and towing a boat it gets about 9... ...If it had 3:50 gears it would most likely get over 20 unloaded...

...So what is my dailey driver,...a '99 Ford expedition 4X4 with a 5.4 gas motor... ...It gets 7.6 around town... ...Nobody has ever accused me of leading a very logical life???....

That's the highest I have ever heard of on a 300SD. Most seem to net 22-26 mpg, as evidenced by the owner's fuel receipts...

I'm running a 2.47:1 axle in a 1978 300SD and I cannot get anywhere near 40 mpg...

Doktor Bert · #**137** 07-09-2013, 12:45 PM

Quote:

Originally Posted by floydla1

I have had my 2003 300SD since 2008. 25 mpg average over several road trips of 400 miles or more...

Yep, that's about my overall average in a 1978 300SD...average is the keyword here.

When I was with my previous job, and commuting in and out of Palm Springs, I was running uphill between Palm Springs and Whitewater everyday against a 40-50 mph headwind out of the west, then up Cajon Pass, which is a 6% grade uphill.

In the morning, going into Palm Springs, the winds were out of the east at 30-40 mph, so you faced a headwind both directions and I think this really hurt my fuel economy numbers, since I was running 4th gear WOT uphill against the headwind with the A/C on...

Doktor Bert · #**138** 07-10-2013, 10:42 AM

Of course, I am running my ALDA all the way out CCW. There are a total of 8 turns available on the ALDA from full CW to full CCW. Most IP's will have the ALDA set at 3 turns in from full CCW in factory calibration.

Last night, as an experiment, I adjusted my ALDA CW until the black smoke under acceleration was no longer visible. This worked out to a setting of 5 turns in (CW) and although my idle speed dropped and off-boost power was negatively affected (as expected) I am curious to see where this places my fuel economy.

I will observe and report...

Doktor Bert · #**139** 07-10-2013, 10:55 AM

P.S. I can drop the engine's idle speed 350 rpm from the ALDA alone....FWIW

DrLou · #**140** 07-10-2013, 11:00 AM

1983 300SD - 400K+ miles. Original injectors and needs a valve adjustment!:

Recent highway run, pretty smooth 70mph or so: 25mpg

Earlier test: mixed highway/stop and go in town driving, A/C running all the time. Bad compressor, so high load: 16 mpg.

Doktor Bert · #**141** 07-10-2013, 11:06 AM

22-28 is easy for me to get, and I think that's about averaghe 617 economy, but my colleague has a Benz C230 that gets consistent 32 mpg with the A/C on, so for all the noise and lack of power, I feel the 617 should be making more MPG...

Let's see what an ALDA adjustment nets us....

Mölyapina · #**142** 07-10-2013, 11:18 AM

Quote:

Originally Posted by Doktor Bert

That's the highest I have ever heard of on a 300SD. Most seem to net 22-26 mpg, as evidenced by the owner's fuel receipts...

I'm running a 2.47:1 axle in a 1978 300SD and I cannot get anywhere near 40 mpg...

It sounds like he either does some runs that are largely downhilll or has a fast odometer. But you still haven't explained your 80 MPG run!

Doktor Bert · #**143** 07-10-2013, 11:42 AM

Quote:

Originally Posted by Jooseppi Luna

It sounds like he either does some runs that are largely downhilll or has a fast odometer. But you still haven't explained your 80 MPG run!

In a word, RPM reduction.

I used to get 26-28 (sometimes 30) at a religious 55-60, but that's a nearly impossible speed to drive on modern freeways. When I swapped in the 2.47:1 axle, my MPG stayed the same at the same rpm, only now I was doing 80 mph by virtue of the axle swap....

tjts1 · #**144** 07-10-2013, 11:54 AM

Quote:

Originally Posted by Doktor Bert

Last night, as an experiment, I adjusted my ALDA CW until the black smoke under acceleration was no longer visible. This worked out to a setting of 5 turns in (CW) and although my idle speed dropped and off-boost power was negatively affected (as expected) I am curious to see where this places my fuel economy.

When I removed the ALDA my fuel economy improved. Go figure.

Doktor Bert · #**145** 07-10-2013, 12:19 PM

Quote:

Originally Posted by tjts1

When I removed the ALDA my fuel economy improved. Go figure.

That is strange indeed!!!!

Already my 'feeling' is the fuel economy has improved, but will have to wait to digest a full tank before I can post anything...

Mölyapina · #**146** 07-10-2013, 02:41 PM

Quote:

Originally Posted by tjts1

When I removed the ALDA my fuel economy improved. Go figure.

Could it be that something along the line was plugged up? Does that make any sense?

Doktor Bert · #**147** 07-10-2013, 02:59 PM

When I was working for Rolls-Royce in Palm Springs, I would leave the 300SD idling with the A/C on all day long so it would be cooled off when I needed to run errands, and occasionally, take clients home. They loved riding in the old 300SD and remarked on how cold the A/C was.

That car would idle for 8 hours a day (never over 175°F) and use less than 1/4 tank on the gauge...

People always said it was bad for the engine and I would laugh when I thought how we used to leave or 4.6 Crown Vic's and Mustang's idling 8 hours a day for 300,000 miles and then we gave them to Public Works and they are still running... :-)

tjts1 · #**148** 07-10-2013, 05:05 PM

Quote:

Originally Posted by Jooseppi Luna

Could it be that something along the line was plugged up? Does that make any sense?

Maybe. I replaced all the hoses, then tried direct hose from the manifold to the ALDA, replaced the ALDA with an unmolested unit from the JY, then rebuilt my own old ALDA and reinstalled it, then finally got fed up with the non linear throttle response and ditched the whole mechanism. Its especially annoying when you're trying to slip the clutch in first gear and the engine refuses to make any power until its warmed up. Without the ALDA throttle response is crisp and it only smokes if I put my foot to the floor and keep it there all the way past 4000rpm. I can live with that.

Doktor Bert · #**149** 07-10-2013, 05:36 PM

Quote:

Originally Posted by tjts1

Without the ALDA throttle response is crisp and it only smokes if I put my foot to the floor and keep it there all the way past 4000rpm. I can live with that.

Calibration is definitely an issue at play here. I ran without the ALDA and smoke was evident even at 2000 rpm...

Power was fantastic...

winmutt · #**150** 07-11-2013, 01:48 AM

I reallllllly want to replace my ALDA with something electronic. I seems the ELR is perfect for this but I am not sure about the stroke or pressure required. Taking off my manifold so I can go from 200hp to 300hp is a chore. I want buttons damnit.