View Full Version : Low MPG

01-19-2014, 03:11 PM
New to the forum here. I have a 2012 Cargo Van 2500 High Top, currently with 12,000 miles. Had a problem with it running sluggish and took it to a service garage a few months back. They said the code came up with a problem with the Diesel Particulate Filter, but that it was OK and they reset the computer. Also had them do the 10,000 mile maintenance.

After that, Van now runs fine except loses power at 80 mph if I go that high. Also seemed to be using more fuel, so I added a Scan Gauge and it shows I am only getting 7-10 MPG.

Any ideas. Thanks.


01-19-2014, 04:25 PM
How did you set your Scan Gauge II up?
Basic Setup Parameters
Distance Units Miles
Fuel Units FUEL UNITS Gallons
Temperature Units TEMP UNITS Fahrenheit (˚F)
Engine Size ENGINE SIZE 3.0 (Liters)
Tank Size TANK SIZE 26....Gallons
Currency Type CURRENCY ..$..

The above settings are the most common for an OM-642 3.0 liter V6 NCV3 in the USA.

I take it you do not have the steering wheel buttons that give you the calculated MPG in your dash display panel...right?

When it was running sluggishly and you took it to the "service garage" was this a Mercedes or Freightliner dealer....or something else?
An authorized Mercedes Benz Sprinter dealer could have run a "forced" DPF regeneration (basically it uses a very high temperature to
turn all the particulates in your DPF to ash which will blow out through your exhaust pipe).
If you did not get the forced regeneration, it might be smart to go to an authorized MB Sprinter dealer and have this service performed using the MB SDS diagnostic system computer. Don't think any other diagnostic computers can do the forced regeneration.

Do you have the invoice on the 10k "A" service?
What oil does it say that they used to refill your engine (13 quarts)?

ALL NAS (USA specification) Sprinters lose power @ 80-83 MPH........ that is the speed limiter setting!

What parameters are you monitoring on your Scan Gauge II?
Upper left= LOD (your current % engine Load)
Upper right=MPH (your current Speed)
Lower left= GPH (your current fuel flow rate)
Lower right= RPM (your current engine RPM)
When you drive, do you simply put the gear shift lever in the "D" (drive) position and let the engine
and transmission work automatically?
If so, watch the % engine load (LOD) parameter and see how much of the time it reads > 70%.
Unless you are trying to go => 75 mph, you may be able to reduce the % engine LOD and fueling rate significantly by
manually downshifting your transmission to 4th gear.
It's easy, simply quickly tap the shift lever to the left and it will downshift the transmission to 4th gear.
You can do this also while running with the Cruise control engaged.
See if your %LOD drops by 5% or more.
Check your fueling Rate (GPH) to see if you are saving > 0.5 MPG.
Don't worry, there are programmed in safeguards to prevent you from over revving your engine (>4000 RPM).
If the engine would over rev in the next lower gear, the transmission will refuse to downshift.
This is how you get better fuel economy in a Sprinter!
Hope this helps,

01-19-2014, 04:58 PM
It has a speed limiter of 82 mph iirc. Plus, if you drive Tht fast, pushing a big box into the air, then complain about the fuel mileage, perhaps a lesson in physics is in order.

Seriously, have you calibrated your scan gauge, and/or testing mileage using odo reading and actual fuel pumped over several tanks? DPF shoul d be covered by the emissions warantee assuming he been using the proper oil.


01-19-2014, 06:19 PM
What sailquick & icarus say above...... +1

01-20-2014, 03:12 PM
Thanks for the info. I do have the scan gauge set properly and haven't noticed my load goiing over 60 (no steering wheel buttons). And I usually drive on the highway between 60-65, but was pushing it to get to the airport on time at 80+ mph. Thought that the loss of power over 80 might mean a problem, but thanks for the heads up on the limiter.

Service was done at a Freightliner dealer. Will try to find a Mercedes dealer and have them take a look.


01-20-2014, 03:27 PM
Are you reading the "MPG" PID on your Scan Gauge II or the "AVG" PID?
The Scan Gauge II is a good indicator, but not perfectly accurate as the fuel offset % number keeps changing.
So far, the fuel offset % (averaged over 25 fill ups) for my 2014 is a negative (-) 37.3%.
If you don't have around a NEGATIVE 45% offset (call it a correction factor if you like) then
yes, your Scan Gauge II will read some ridiculously low MPG figures.
I just looked back at my 2012 Spreadsheet and the fuel offset% @~30k miles/~100 refueling stops
was right around -45% so I would expect your fuel offset to be similar.
You have to keep adjusting the offset percentage to keep your Scan Gauge II more accurate.
The real fuel mileage numbers are developed by doing the miles driven / gallons consumed math at each refueling
I carry a calculator specifically for getting the accurate fuel use numbers and well as a spreadsheet that tracks every
penny that goes into my Sprinter.
I use an averaging calculation to correct my fuel offset % at every refueling. I use the previous % + the actual % consumed/2=
the new % offset so I only correct for 1/2 the error.
My 2014 4 cylinder 7 speed is getting 22.9 mpg at ~12,000 miles and 28 tanks of fuel.
Try to find an authorized Mercedes Benz SPRINTER dealer, not just a Mercedes car dealer that does Sprinters on the side.
Call and ask them if they offer a commercial rate for Sprinters....the ones that do commercial are usually better and you get
better pricing and possibly better service as they have the heavy duty lifts/tire/balance machines and all the Sprinter special

01-20-2014, 04:43 PM
I would think the Freightliner dealer if it is equipped for Sprinters would be good as well especially if yours is branded a freightliner Sprinter unless it provides bad service or not properly trained techs. You should also still be under warranty if you have an emission problem and I would go to whatever brand Sprinter you have unless FL will honor MB Warranty if that is how yours is branded. Other threads here about that. Welcome to the forum.

01-21-2014, 05:19 AM
I did some testing on my 310 mile trek this afternoon in the 2014 4cylinder 7 speed.
You must not have calibrated your Scan Gauge II yet.
As suggested above, in my last ~90,000 miles in 3 different NCV3 Sprinters with the OM-642 3.0 liter V6, the fuel correction % factor has run right around - (NEGATIVE) 45%.
If you are running a positive calibration % factor or a zero (0) calibration % factor, you might get 7 mpg as the calibration % is way off.
On my trip tonight , with a calibration % factor of -37.2% the least mileage I could get, pulling up a little grade in 7th gear was 11.5 MPG. @ 99% engine load
(so, maxed out).
As suggested, use -45% as a starting point (I did that on my previous 3 Sprinter V6's from new) and I tried it on the 2014 4 cylinder and got some screwy
MPG figures until I ran a couple of tanks of fuel through it and found that the correction % is significantly different between the V6 and the 4 cylinder.
Hope this helps,