Fuel Mileage

LS12FAST4U · **Posted:** Wed Dec 26, 2012 9:42 pm

Hey guys new guy to the site. I purchased my CRD back in august and have not done much to it. I put a K&N air filter in it as I do a lot of highway driving and i had averaged 26 miles to the gallon at 70 mph. Almost two months ago I purchased the green diesel ECO TUNE. I was hoping to see an immediate increase in mileage on my next fill up but to my surprise I actually only got 22 mpg. I figured it was a fluke and maybe it needed some time for the computer to relearn long term fuel trims. Well I have gone over 3k miles and still at 70mph I can only muster 24mpg while driving very cautious while never exceeding 2k rpm. I was rewarded with the best mpg increase if I drove 55 and all it got was 26.5. I don't understand why it works miracles for everyone else but not me.

I know the Eco tune is written to the vehicle as I loaded it twice and also the egr code was on with the stock tune and is no longer on with the Eco tune.

Any suggestions?

woodtick · **Posted:** Wed Dec 26, 2012 11:04 pm

Is your temp gauge at full warm up reading one needle width left of center? If down closer to the 1/4 mark could have low engine temp causing it to run rich. Also, have you cleaned the MAP sensor? This tends to get caked full of glop. Good luck.

LIBERTYinLIBERTY · **Posted:** Thu Dec 27, 2012 12:33 am

Also the winter blend diesel is thinner.....

captaincrd · **Posted:** Thu Dec 27, 2012 3:51 am

When I got my eco tune my mileage went down a fair bit for the first 1500 miles or so and then it went way up. Not sure why and it was not what I was expecting after everything I have read. Definitely make sure your thermostat is good, my mileage went way down before replacement. I've read in other post that people have had issue with the brakes or parking brake dragging.

naturist · **Posted:** Thu Dec 27, 2012 9:03 pm

@OP you don't say where you are from, but if you are where cold weather is, you'll lose about as much for winter diesel as you gained for the ecotune. You also need to note that a huge factor is how you drive, and not particularly how rapidly you accelerate, but how you brake. After all, using the brakes merely throws away all the fuel you used to get up to speed. It has been proven by the experts that if you can maximize coasting down over using the brakes, you can make as much as about 1/3 difference in fuel usage.

You also need to be aware that speeds above 55 burn fuel at exponentially greater rates. Wind resistance is killer. This accounts for what you saw between 70 and 55.

Finally, there is way too much error measuring "full" due to the foaming factor when you fill up. You'll get much more telling results by averaging several tankfuls.

LS12FAST4U · **Posted:** Thu Dec 27, 2012 9:16 pm

I don't have to brake that often. I live a mile from the freeway and then drive 45 miles to work which is about two miles off the freeway. I live in Idaho but where I'm at has been very mild. Barely below freezing. And again I got the tune months ago when it was still in the 70s here. Temp is right at the halfway mark I replaced the thermostat when I did the timing belt. MAP sensor is good as well.

tedder · **Joined:** Thu Sep 15, 2011 7:19 pm **Posts:** 137

Before ECO tune I got 22/26 after 24/28 not great but it fits what GDE says the ECO tune will do. I drive the speed limit. I have 2= 2006 CDR's one with the overhead electronics and one without. One thing I have learned is the MPG average from the computer is bogus 4-5 MPG too high. Both of my CDR's have ECO tunes and get exactly the same MPG. I Keep hearing that people get 30+ MPG and I say they must drive like grandma or a hell of a tail wind. If all the dynamics are considered weight, aerodynamics, engine fuel requirements, speed and the person driving CDR's can't get much more than 30 MPG under the best conditons. The key factors are weight and aerodynamics the CRD's are heavy and shaped like a box. Compared to the gas models at 20 MPG on a good day I think they do pretty good.

you gotta love diesels to have a CDR.

LS12FAST4U · **Posted:** Thu Dec 27, 2012 9:45 pm

I calculate my mileage based on gallons used and miles driven.

ChooChooman74 · **Posted:** Thu Dec 27, 2012 10:00 pm

tedder wrote:

Before ECO tune I got 22/26 after 24/28 not great but it fits what GDE says the ECO tune will do. I drive the speed limit. I have 2= 2006 CDR's one with the overhead electronics and one without. One thing I have learned is the MPG average from the computer is bogus 4-5 MPG too high. Both of my CDR's have ECO tunes and get exactly the same MPG. I Keep hearing that people get 30+ MPG and I say they must drive like grandma or a hell of a tail wind. If all the dynamics are considered weight, aerodynamics, engine fuel requirements, speed and the person driving CDR's can't get much more than 30 MPG under the best conditons. The key factors are weight and aerodynamics the CRD's are heavy and shaped like a box. Compared to the gas models at 20 MPG on a good day I think they do pretty good.

you gotta love diesels to have a CDR.

CRD :-p

I get just under 30 with my CRD, right now running Firestone Winterforce 245/70R16. I have the currently have the Eco Tune and drive 65 to 70.

Sent from my Nexus 7 using Tapatalk 2

tedder · **Joined:** Thu Sep 15, 2011 7:19 pm **Posts:** 137

what can i yas i evah deslexia. :lol:

tedder · **Joined:** Thu Sep 15, 2011 7:19 pm **Posts:** 137

CRD :-p

I get just under 30 with my CRD, right now running Firestone Winterforce 245/70R16. I have the currently have the Eco Tune and drive 65 to 70.

Sent from my Nexus 7 using Tapatalk 2[/quote]

I noticed your CRD isn't exactly stock could some of those modes be helping your MPG? What Mod do you think helps the most or is it a combination of all?

striperman36 · **Posted:** Fri Dec 28, 2012 1:44 pm

ChooChoo's head rebuild probably helps.

hucorey · **Joined:** Tue Mar 06, 2012 4:29 am **Posts:** 378

What gear ratio are your axles. I do believe they came in 3.55, 3:73, and 4:10. The latter will definitely give you the mileage your at.

Mine has the 3:73 and without the ECO tune I would get 28 on my trips up north. Its actually my wife's ride so I don't know what it would get if I drove it a couple weeks since my commute to work is 80mi round trip. Now my wife on the other hand likes doin hole shots in town :furious:

. For some reason she just can't wait to get to the next red light. So she only gets about 23mpg, which is mostly city driving.

papaindigo · **Posted:** Fri Jan 11, 2013 6:39 pm

IIRC in the US they only came with the 3.73 axle. It's possible the export market got other choices to go with the manual tranny.

As to mpg. Setting aside the host of factors that impact mpg (MAP sensor clean or not, air filter clean or not, winter vs summer fuel, leaky injector seals, terrain, head wind, tow, lead foot, tire weight and pressure, etc) folks who comment on what mpg they get need to be clear on how they compute that figure. The EVIC is a known source of error and can be worse with a GDE tune so that's not a reliable source of data between vehicles although it can give you a hint on your vehicle if you know what the EVIC error is. Computing from the odometer and gallons used is better but still a problem as the odometer is commonly off by up to 5% and don't get me started on the "accuracy" of mile markers. Computing using GPS corrected odometer data is good but be sure to run several GPS vs odometer calculations to get an accurate correction factor. Finally the only way to be absolutely sure that the amount of fuel being put in at each fill is comparable to the last fill is to at least fill until you can see unfoamed fuel in the filler neck, ideally at the same station same pump.

I can tell you for an absolute fact using GPS data and the fill to the filler neck techique that I got an average of 32.0mpg on a 2,000 mile trip, mostly interstate at 1800 rpm. Mpg ranged from a low of 29.7 (some rain and consistent headwinds) to a high of 33.9 (61-62 mph or 1,800 rpm with/without AC). Do I get that on the highway all the time - no but I expect 29-33. Similarly in town I expect 20-24. Have I done worse - your darn right and I don't even want to mention what I got to>from North Carolina dragging a heavy as you know what flat trailer with a big ramp sticking up in the air like a drogue chute. Felt like I was towing (more like dragging) an anchor and felt much worse than the cross country tow in stoutdog's fully loaded 06 with kayak on roof pulling a fully loaded 5X8 Uhaul.

PS without the GDE tune I'd expect 26-28 hwy and 17-19 in town which is what I got from both my 05s without the tune.

hucorey · **Joined:** Tue Mar 06, 2012 4:29 am **Posts:** 378

papaindigo wrote:

IIRC in the US they only came with the 3.73 axle. It's possible the export market got other choices to go with the manual tranny.

I'm sure you're right about the axles. The one I was looking at must have been a mistake on the dealer listing because the 4cyl gassers came with 4:10

PS without the GDE tune I'd expect 26-28 hwy and 17-19 in town which is what I got from both my 05s without the tune.

I would think with trans upgrades and a quality TC one may be just fine to install 3:55's with the GDE tunes.

hucorey · **Joined:** Tue Mar 06, 2012 4:29 am **Posts:** 378

LIBERTYinLIBERTY wrote:

Also the winter blend diesel is thinner.....

At least in NWOhio winter blend is either 20% biodiesel or 20% kerosene. Depending on the gas station.

Fuel Mileage

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