Fuel economy for the forest river 2004

Saturn949

Member
Hi, I just got 2005 MB cruser on 2004 freightliner 2500 chassis and I wonder about what will be the normal fuel economy for stock. I'm getting 22mpg onli if I drive as an very old lady -60'mph. If I speed up to 67-70going i5 in northern CA I get only 17mpg. This is my first sprinter disel and I need to know if it is normal? Is there recommended modifications to this rv? Is it worth it to try bullydog performance adapters for 500$ would be nice to have forum opinion.
 

sailquik

Well-known member
Saturn949,
Next time you are out and about in your 2005 MB Cruiser, stop at a truck stop and pay the small fee to have it weighed.
I'll bet it weighs very close to the GAWR for the 2005 Sprinter model it was built from.
There's your answer.
It weighs a lot, and it pushes a lot of air, so you get poorer fuel mileage the more you push it.
A Scan Gauge II, set to read the % engine Load, the RPM, Gallons per Hour, and your actual MPH (your speed is probably overstated by ~ 3 mph in that Sprinter) will tell you why you are using so much fuel.
You could get it tuned (Bully Dog/GDE/ etc) but that may get your better fuel mileage but cause other problems.
If you learn to manually downshift your Sprinter based RV to keep the % engine LOAD as low as possible, and begin to drive more by the % LOAD and GPH I think you will see 20-22 mpg at slightly higher rates of travel.
If you just put it in cruise control, and let it run, it will use way more fuel because the transmission does not auto downshift when it's needed for best performance or best fuel mileage.
It will lug along, in 5th gear overdrive, using 2x to 3x or greater fuel flow, with the engine at 100% load and losing the horsepower battle (slowing down due to not enough power in top gear).
A quick tap of the shift lever to the left, and voila....you are in 4th gear (sometimes even 3rd gear is needed) and the engine is running up in the most efficient and powerful RPM range (2700-3150 RPM) and the fueling rate goes down by => 50%.
Roger
 
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smiller

2008 View J (2007 NCV3 3500)
I'd like to get mileage that good. My Winnebago View on a 2008 3500 chassis weighs very close to its 11030 lb max gross weight going down the road and between that and the extra wind resistance I get about 16 mpg at 60 mph, which is normal for that configuration (beats the 8-10 mpg I'd be getting with gas.) As always you have to pay for vehicle size and weight.
 

Saturn949

Member
You right! I have never think about the weight of the rig. Even so we are not carrying bunch of close but 30 gallons of fresh, gray and black water all cabinetry 7 gallons full LPG tank. I did upgraded house battery to 200AHr LiFePo battery with I barely loaded in place of original battery, added xantrex 1000w inverter, I did replaced fridge to dorm type for 65$ from Wallmart.
You got me wonder how much do all of it weight, I will check and report latter.
On other note, I do have scanguage and I have it on mpg instant , combined gps and engine temp. With this I had hard time to figured out best driving habits. I will try to use load% instead of engene temp. And also I was not aware of keeping in lower load instead rpm- good point. Oh and I use disel-A settings on scanguage.
I whant to try all techniques first before going in to ECM programmers and over boosting turbos.
Aerodynamics wise I noticed if I look from front of the rig at my running boards - the wheels are really inside and plastic skirt is really sticking out making whole van wider. I bet all of thouse side running boards despite fiberglass weight a lot. Does it make sense to maybe remove them at once from all around the truck to make it lighter and narrow as original sprinter. Just wonder if anyone done this.

Oh and of course now I will try convince my better half not to carry ceramic plates and cups and replace them with paper ones for better fuel economy
 
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mbcruiser

05 Sprinter/06 MB Cruiser
Congrats on your acquisition....
Running in 60-65 mph ranges with 22 mpg is fairly reasonable... at 70+ mph my experience has been an mpg in 17-20 range, so I try to keep it in "mosey" mode unless this mode is a hazard to the traffic flow.
I have OEM (no performance enhancing gear installed) 2005 chassis (2006 Forest River MBCruiser) with 110k+ miles and faithfully tracked mileage since new (I'm it's only owner), and overall have seen 22-23 mpg. Admittedly it's probably 98% highway miles, but that includes city, backcountry roads, mountains, headwinds (this is a real mpg reducer with the high top), tailwinds (this is where mpg in 25-27 has been documented), and cold weather conditions.
I've even scored 27 mpg with 5 people and assorted camping gear on board but in an area where speed limit was under 50 mph. The other extreme was going 70 into a 30+ mph headwind where 17 mpg was recorded. Cold weather local driving (around town) gives similar results.
Hauling the 30 gallons of H2O (fresh, gray, black tanks) and LP probably make only a tiny fractional difference... though the swapping of dishes for paper plates is something I haven't thought of... though I suspect :hmmm:the weight differential would only increase mpg by a factor of 0.0000000003456 (hence why I don't think it's worth it worrying about when enjoying a nice steak on the barbecue!)
Just my :2cents:
Or as they say, 'your mileage may vary'......
 
The only way to increase your mileage it to remove all the junk on the top of your MB Cruiser. Since the air conditioner, two vents and Omni TV antenna are part of the enjoyment of your rig, just drive it and enjoy. Do not mess with the CPU. Any mileage improvements you make will be cancelled out by headwinds. My MB Cruiser gets from 15 to 25 MPG, depending on the wind direction.
 

Saturn949

Member
Thank you all for the group intervention. It is greate to become the part of this community. Indeed switching from empty Vw eurovan to 159 sprinter with tanks and interior is quite a changhe and I was keep thinking that it similar to the VW.
Ok just got back from the test driving rig on flat hwy 65 mph scan gauge show 55% engene load 2300rpm no headwinds fuel consumption about 18.5 mpg with is about 20 at the pump.
To keep engene load under 50% I had to slow down to 55mph. :bash:
I have everything is stock and roof configuration max air then antenna then ac.
I did not anticipated that it would tale more then 50% engene load to push this van. :idunno:
Any advice?
 
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nekit

Member
I have a 2007 Leisure Travel Free Spirit(2006 chassis), similar to your MB cruiser. I've had it since June and have put 7k miles on it mainly highway driving, flat ground and mountains. I ran only 2 tanks in stock configuration and got 22 & 24 mpg. I then installed Green Diesel Tune and have been getting 23.5 avg, low 22, high 24. Not much different than stock, but I didn't drive it enough in the stock configuration to get a good base. I drive it at 68mph on the scan gauge or 72 on the speedo in most hwy driving.
 

von van

New member
my mb crusier weighs 7000 lbs, 3 on the front and 4 on the rear axle. it was converted in 2005 and is stock. I down shift at 75-80% engine load, unless it's a short pull to the top, when I let the inline 5 diesel do its torquey magic. 22 mpg is avgerage cause I drive 55 to 65 where the machine's groove seems to be. Ya I've hit 85 going down hill under good conditions but may lose 20mph on the grade up. variety the spice of life
 

Saturn949

Member
Ok. Problem solved. After my last trip 600 mies and 160 of thouse on mountin rods. I have noticed a wet spot on radiator fan shroud right on left bottom near tTURBO Resonator!!! So turned out my resonator have little crack in weld but it was so small to loose turbo pressure bot not enough to set trouble code. Replaced turbo resonator Q3 with Doorman from amazon few days ago and on test drove. Now my engene sounds better, I have strong pull every time I push gas and guess what on the same road stretch where I had 18 mpg reported on scanguage now it is around 22-21 mpg. I have not done any long trips et to get actual consumption but I'm positive the stupid turbo resonator was a problem. Will report actual mileage soon.
 

sailquik

Well-known member
Saturn949,
You might want to try running the PID (Parameter Identification Code (Guess it would be PIC, but that's no what Linear Logic/Scan Gauge II calls it) GPH.
The GPH PID can tell you a lot in a Sprinter (any Sprinter) as it gives you the amount of fuel being pushed to your fuel injectors.
You will see that when your % engine LOD (the primary indicator for use in Sprinters) is @ 50-60% you are using the least amount of fuel (GPH) for your current speed and wind/environmental/geographic conditions (Uphill/downhill/flat/etc).
As the % engine LOD increases from 60% to 70% you can see the fuel flow rate (GPH) increase to ~1.5 x the 50-60% rate.
If you continue to accelerate or pull up a hill, the % engine LOD will increase to the 70-80% range and you will be using ~ 2x as much fuel (GPH here) as you would if you manually downshifted to get the RPM up into the 2700-3150 RPM optimum power and mileage range.
If you continue to stay in 5th gear overdrive (without downshifting manually) you can see the % engine LOD increase all the way to 99%.
Now look at the GPH.....you are using 2-3 x more fuel than you were at 50-60% engine LOD.
MPG is nice, but it's not very linear and it changes too rapidly to really track easily.
GPH just shows you the amount of fuel the engine is burning currently.
Making a proactive choice to manually downshift early when conditions (uphill/headwinds/heavier than normal loads inside your Sprinter/towing a trailer) you can save a significant amount of fuel....and get better performance and better mileage by running @ increased RPM (2700-3150) but reducing the % engine LOD and the GPH.
Give it a try.....I've run most of the way across Minnesota, towing ~ a 5,000 lb. 7'wide x 14' long x tall as a high top Sprinter (it's the trailer in my Avatar photo) in 4th gear due to 20-35 mph headwinds. I got ~12-14 MPG in 5th gear but improved to 14-16 mpg @ 60-65 MPG by manually downshifting. I ran for > 300 miles at this RPM/speed more than once.
Oh, and trying to track MPG on a Scan Gauge II only gets partially accurate when you get the fuel offset percentage (you do this @ the fill up screen) really accurate.
My T1N (2006 3500 158" long tall with 4.182 : 1 differential ratio) used a fairly large fuel offset percentage number. (Like -45% as I recall).
With my 2014 516/3500 tall short back with the OM-651 4 cylinder and 7G-Tronic 7 speed transmission (same rear end ratio of 4.182:1) I've gotten the fuel offset percentage down to less that -6% and have been seeing -3.5% to -5.5% pretty consistently with 42k miles on the vehicle.
My fuel mileage numbers are very close between the Sprinter's system, the Scan Gauge II system and the actual gallons used/miles traveled when refilling the tank.
I use a spreadsheet to track all these numbers and they have settled down very nicely.
Hope this helps,
Roger
 
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