Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

If you experience loading issues with the login/register form, please completely disable ad blocker or use an incognito or in-private window to log in.

Chevy Silverado and GMC Sierra Duramax Fuel Mileage



  • Good morning everbody. Hey, I just took a look at powerup diesel . Biz. The tuner I bloged about is on sale for 427. Check the site out
  • I chopped my truck as soon as I got it. I can dial in economy or power. It saves my truck and my wallet. I suggest that the way the truck ahs been used and maintained is the most important thing to look at.
  • went to powerup diesel and bought their programer. noticeable throttle responce on the lowest setting, but do to the cold weather, can't determine if mileage has improved as of yet. I just want to make sure how everyone is determining their fuel mileage. Gallons in, divided into miles driven. Not what the DIC average tells you. EVERY one I ask how they determined their miles and they're to content with just using the drivers information center. So far, my best mileage has been 17.5 hiway staying under 70mph on flat terrain with the stock settings. Stay tuned to see if the programer improves mileage.
  • Hi everyone, merry chrismas to all. Glad to hear you have the programmer. Reprogram to the 60 hp setting. This is said to give best economy. Now a few facts about winter fuel. Where do you live? Is your fuel cut with kerosene? This is what is called 1d. Gives the fuel a higher cetane rating. Kerosene is 60. But lowers the btu of the fuel. You will get poor milage with this. Fuel quality varies from one pump. Brand and another. What year truck do you have, what gearing? Me I have 06 with 3.73 4wd. With the tune I have to drive In fifth gear. Get engine up to 1900 rpm. I'd say around 22, 23 mpg at 63 mph. As far as checking your milage, fill it to the top of the neck, drive and then recheck.
  • Hi all, I'm not sure this is the correct forum. I have a 2004 GMC Sierra 2500HD. I have an Afe cold air intake stage 2 system installed. I am constantly getting a "check engine" light on all the time. No matter what I do the "check engine" is usually on. I have tried cleaning the air filter but to no avail. Every once in awhile the "check engine" light will go off but only temporarily. As soon as I accelerate the light comes back on. Someone told me it could be the max air flow sensor that is mounted on the intake pipe that comes from the filter and goes to the engine. Does anyone know what causes the "check engine" to stay on and is there a permanent fix? It is driving me crazy. Any help would be greatly appreciated.
  • coontie66coontie66 Posts: 110
    edited December 2010
    Exactly a year my check engine light on my 06 started coming on and never went off. Chev folks look at it 4 times or so and cleaned the turbo and other turbo related things until they replace it. Problem solved.

    You need to put it on the computer and see what the error code is.
  • I think you have messed with a complex computer system. It could be you have too much restriction. I know the people who sell those systems say they flow better but do they have as big a stake in it working correctly as GM. Check the package or web site it will basically say use at your own risk. My 06 filter seems to let nothing through for the passage behind it is very clean. Just checked it less than a month ago. I have replaced the filter 4 times so far. I can not imagine changing the intake setup without other major changes such as new higher flow turbo along with intercooler, piping, manifold and electronics changes. One can get slightly better power by reducing exhaust restrictions which also leads to cooler EGT temperatures. My Guess would be you are having EGT problems which can happen with too much air(runs lean) or too little. A diesel is a simple engine but made more complex be the turbo. Messing with intake can be a route to turbo failure.
  • I agree with the guy who told you to find out what code your getting. A thought I'm getting right now, clean your mass air flow sensor. Use either or carb cleaner. Engine OFF. SEE what happens
  • Thank you very much for your input. My truck is not a diesel and does not have turbo. It has the 6.0L gas engine. With that in mind, I don't believe it is having EGT problems. Along with the Afe cold air intake, I also had dual Areo turbine mufflers installed. I don't know if that makes a difference or not. I guess I will need to get it on the computer to see what the error code is and then go from there. Again, thanks for you input and time.
  • A gas engines computer system is even more complex than a diesels due to the emissions control system and the ignition system. Many, Many of the check engine light on situations with a gas engine are due to some component of the emissions system getting old and worn out. A computer code check should tell you what is wrong or at least what system is failing. Most common is EGR valves getting gummed up or Oxygen sensors that are in the exhaust manifold along with an EGT sensor getting literally burned out. Your truck is 7 model years old and was most likely built in late 03 to very early 04 so it most likely has enough miles to make these things a problem. You can replace them yourself if you get the correct diagnosis. Good luck
  • Thank you very much for your input. Just some added information, my truck is not a diesel and does not have turbo. It has the 6.0L gas engine. Along with the Afe cold air intake, I also had dual Areo turbine mufflers installed. I don't know if that makes a difference or not. I guess I will need to get it on the computer to see what the error code is and then go from there. Also, I will try the mass air flow sensor cleaning and see what that does. Again, thanks for you input and time.
  • The guy who wrote post 558 was right on the money. I thought you ran diesel. The reason I said clean the mass air flow sensor is you said you cleaned and I presume reoiled the air filter a few times. The engine will pull oil into air intake, and coat the sensor. You said it went out sometimes. Try it see what happens. If not go get the dtc codes. Hope you find your trouble
  • barrailbarrail Posts: 27
    To hillsdale56 , I responded on 1/4/11 but can't find my thread anywhere. So lets try this again. I havea '05 lly with 373's and line in the suburbs of chicago. 500' above sea level. I agree with filling the throte on the fuel tank to check mileage. always buy my fuel at the local Farm Service where the local school busses fill up. Did I understand you correctly to say that you can't run your truck in 6 lockup? Hope this thread gets to you.
  • Hey what's up? What you read is true. When diesel domination reprograms the ecm, it brings the max torque to 1900~ 2000 rpm. I have 373 also. My engine runs around. 63 mph. The engine runs stronger in fifth now. The easy tuner has a feature to monitor engine performance. That is sure way to tell. I have to have someone with me to watch the screen and see where the highest turbo boost is. I will post a thread when I do this
  • keygmckeygmc Posts: 1
    I Have Solved my mileage problems on my 2008 duramax crew cab 4x4. I was getting 14.7 MPG . I did some research and found that in order for GM to meet the new emission standards they installed a particulate filter in the exhaust. This filter has fuel injected directly into the exhaust for it to work. This results in clean exhaust and poor fuel mileage. Now for the solution. I ordered a tuner the brand is H&S this tuner has a dpf ( Diesel Particulate Filter ) Delete which will allow you to replace the entire exhaust system from the turbo back and not set any codes in the ECM. I installed a new 4" exhaust and cold air intake system ( Banks ) . I could not believe the difference. The H&S system has 4 different power levels I rum on the hot or highest power level for best milage. I am now getting 20.2 MPG around town and 26.1 Mpg Highway.
    I used to have the bully dog tuner on this truck with no milage improvement but good power but with these mods. This truck is pure mean I recomend everyone make these mods. It cost me about $1,200.00 for the tuner and exhaust. Well worth it especialy when I can out run just about any car or truck on the road.
  • Glad to read about your good results. Right now I have a half a ton of wood in the back of my ride. With all the snow we are getting here in new york, I'll. Never get stuck. But its killing my city fuel economy. Stay warm
  • I'm real interested in the results you experienced with the H&S tuner. I to have a 2008 2500 duramax that averages around 14 mpg. Which exact set up did you purchase ? Whats involved with the installation? How many miles have you driven with the new tuner? Are you precise with your mileage estimates? What are you getting city and highway? Thanks for your response.
  • With this price just over the horizon again, like back in '08, I know that I can drive my '06 Duramax diesel for much better than the 18 mpg I have been accepting for quite awhile. All I have to do is slow down my acceleration after 30 mph and drive at 55 mph as much as I can. People have short memories but I can say that back in '06 to late '08 drivers of all kinds of vehicles did slow down and did save money. I would expect that driving 15 mph slower will result in a mileage increase of 6 to 7 mpg highway and 5 to 7 mpg city. This is all based on my '06 Duramax results over the last 5 years. I have always tried to drive for better mileage since fuel has rarely been below $3.00/ gallon since I have owned the truck.
  • Hi, sorry it has taken me so long to get back to you. We are all feeling the pain at the pump. The mideast is in flames and oil has gone over 100 dollars a barrel. Know the name denise rich ? One of bill clintons inner circle. Her x husband marc rich is the one who put crude oil on the comodities market. The real reason I wanted to answer you is this. Remember my last post I said the wood I was driving around with for almost a month was killing my fuel economy?. Wasn't the wood. It was number 1 diesel. With this winter we have had. They have put a lot of kerosene in the fuel. When it hits 5 bucks a gallon, buy that time we will switch back too 2d . It was 8 degrees in upstate ny, last Sunday morning. What a winter!
  • The tip about getting the engine to run at 180 degrees made a little difference in the trucks mileage. If nothing else, the cab warmed up sooner. Bottom line, if you want better mileage, stay off the throttle. I presently have the easy tuner set at 80 e. at the engine responce is very noticible. Fun to drive. Doing more highway driving now, but the mileage still is not 20 mph. stay tuned and thanks for all your input.
  • Interesting reading...

    Our '07 2500 Classic is great but for the mileage... avg. 13 mostly hwy and between 9-11 towing a tiny little 2 horse bumper pull with 2 ponies! Grrr. It's got 55K miles and has been well maintained.

    My old '03 Duramax got 21 hwy 17 city... and towing got around 16 pulling a bigger trailer with bigger horses. I was hoping to get the same or better.

    When I did the research before I bought this truck, all said the mileage was similar to the '03... now I see these threads and wonder what's going on?

    Is anyone out there getting good mileage at all? If so, enlighten us!
  • rgferrirgferri Posts: 3
    edited March 2011
    I have a 2006 2500hd crew cab with a 3.73. i was wondering if anyone has some advice for better milage. right now im getting about 11 in the city. was driving a 2004 sierra 2500 and getting 17.5 in city. both truck are bone stock. any pointers?? thanks!!!!
  • first question: is it a diesel??? If not that is about the best you are going to get. Crew cabs weigh a lot more. If it is a diesel then I recommend you decide if you like the acceleration more than mileage. Take it easy on the diesel and you will get better mileage. If that doesn't work then the next easy step is disconnect the batteries, causing a transmission computer reset and then drive it easy. The Allison tranny behind the Duramax is a learning computer for shift points and the more hard acceleration the less up shift and fuel savings. Also the faster you drive the less fuel savings from the engine computer and tranny computer. An '06 diesel is the best one GM has produced lately for mileage.
  • rgferrirgferri Posts: 3
    thanks for the advice. Yes it is a diesel. I just purchased it used and the computer said 10mpg and after a few days of driving i brought it up to 11.1 mpg. i have only been driving it for about 3 days now. i am hoping it keeps going up from there. I guess i was expecting mileage like my fathers 2004 duramax. is it taking me longer to raise the mpg because it has been at 10mpg for so long. would re-setting the computer on the instrument panel give me a more accurate reading??? any aftermarket products you guys suggest??? the truck has 104,800 miles on it so i am not worried about the warranty.
  • Oh yeah, reset that stupid display. The DIC that you are getting your MPG stat from arrives at it's calculation from the float position in the tank and the throttle position which means your pedal position as you drive. It is horribly inaccurate and the longer you leave it the farther off it will be. Mine say 14.4 mpg right now because I haven't changed it all winter. Winter is when a diesel gets the worst mileage for a diesel engine is most efficient when the engine is hot. I do not know where you live but here in MN I not only have the "Winter Front" covers on the grill and bumper, I added cardboard from the radiator down in front of the tranny radiator plus I covered the 2 holes left open on the bumper for the tow hooks with cardboard. This winter has been really cold but my drivetrain temps have been good thanks to the block heater and all the covers. No tendency to overheat either even on the few days that have been in the upper 40's or 50. So my calculated mileage at the pump has been 17 to 19 this winter. Close to the lowest I have seen in 50,000+ miles. Spring through fall I get 20 to 22 city(with No load) and when I tow our 16,000 lbs of boat we get 13 to 15. It really matters how you handle the drivetrain. I moderately accelerate to 35 mpg then back off and let it shift to 4th and if needed keep accelerating easy to highway speed. Maximum economical speed is 65 to 67 mph depending on head wind. I can hear the engine start to work harder in 6th with the torque converter locked up somewhere around that speed. It is the complete lack of aerodynamics of the truck which is like shoving a large stack of bricks through the air. But the dash MPG estimate is always off by 3 to 5 mpg or more for me since I have a steep driveway that it has to climb. Also you do not need to idle the truck when you stop to keep it warm for it has a huge amount of fluids that stay warm quite awhile. If you need more advice feel free to let me know if you need my email addy. Oh and if you wish to "chip" your truck get a tuner that connects in the wire connectors under the hood. The ones that plug in inside are DANgerous. For mileage without a load the lower program settings add air to the engine with the higher power setting adding fuel and air. High power settings are for people who need or wish to show off the diesel power but they can easily damage a transmission. The Allison is the "weak" point in the drivetrain but it can handle as much as 15% more power if it is in good condition. To check that have the fluid changed for the external filter has a magnet in it to detect how well it is operating.
  • rgferrirgferri Posts: 3
    Thanks a lot. Great help!!! I'm not an aggressive driver by any means, i just want to get better mpg. we never reset my dads in-dash mpg display and for some reason it always ready about 17 city and 21 highway. hopefully like you said with me resetting that mpg feature it will start to show more accurate readings. as for idling the truck, i usually don't let it idle......its garage parked so it doesn't get really cold even though this winter was one of the harsher winters Ive seen. I'm from Michigan by the way....sorry if i didn't give you that bit of info...ha ha so yea we have had a cold one this year as well, maybe not as cold as you guys but close enough.

    Thanks again for all your input and info!!
  • kula_jonkula_jon Posts: 1
    Hi, I bought the H&S XRT Pro package with the cold air intake and DPF delete pipe. I just unplugged my EGR and air intake valve connections. I just switched to "hot". I have not seen the gains that you're speaking of, up to this point. I was getting 13.3 and it went to 14.4 but that's all. Am I missing something? I seem to have copied your setup (except I don't have Banks, I have S&B intake).I have a 08 2500 HD with the 6.6 LMM Duramax, extended cab, Allison trans, 4x4 LTZ. I upgraded so I could haul my backhoe. Since it's so dang slow I'm not hauling anything these days.
    I'd appreciate any pointers. Thanks.
  • My quick reply would be that if you didn't replace the computer with one that can work with the stock system you bought the wrong computer. Banks, Edge systems and another all have the purchaser install a "Y" connecter under the hood in the main wiring loop between the stock computer and the engine. They also add an EGT sensor on each manifold. The cold air intake + the bigger intercooler + the bigger exhaust w/o obstructions is how you get to run power levels higher than 2 steps above stock. The upper 3 or 4 power levels are NOT recommended for a stock transmission. Stock Allisons of that year are capable of around 750 ft-lbs without damage. I found all this out for I exceed the GCWR of my truck by about 4,000 lbs when towing our 18,000 lbs of boat & triple axle trailer with us loaded out for a vacation in the bed and cab of our '06 Duramax which still can get 14 to 15 the way I drive it under load with the first 2 power settings. At stock I get 11 to 13. My installer did not disconnect any of the stock systems, just added systems onto the stock which quails more mileage and performance. I did this because I lost so much when 500 ppm fuel became unavailable after '08. My guess is that you have actually hurt your performance and perhaps endangered the engine and transmission. good luck with that.
  • jerryeljerryel Posts: 2
    My fuel economy is 14.8 mpg empty according to the truck computer. My 02 Duramax got over 20 mpg empty and around 12 mpg pulling my travel trailer. I only have 1200 miles on the 2011 and baby the engine. I never drive over 65 and most of the time I drive 55 mph. I recently took the truck to the dealer for a diagnostic check and they couldn't find anything wrong? All the reports I have read state that this truck gets from 18 to 22 mpg on the highway empty driving at 65! Is mine just a lemon? or do I need to wait 5000 or 10,000 miles for the fuel economy to improve? My 02 Duramax had a Bully Dog chip set at "towing". It also had the 4" exhaust(no catalytic converter), an Air Raid air cleaner and the Air Raid air intake ring. I love the new 2011 Chevy Silverado but not the fuel economy....Jerry
Sign In or Register to comment.