Hi All,

As my title says I have lost nearly 3 miles to the gallon on my last 3 tank fulls, I was getting 19.5 -19.8 :) hand calculated and on the DIC now I am getting 16.2 - 16.6 :mad: . Nothing has changed and everything seams the same on the truck, I have 19,550 miles on it and I have been averaging 19.5+ for about 10K miles now. Any help would be greatly appreciated and thanks ahead of time.

Dont forget to reset the DIC. Took me almost a year to figure that one out. :(

Air filter? Have you been sitting at idle longer?

Have the dealer check for codes. Somebody on here had the same problem. The CEL was not coming on, but the EGR was still throwing a code.

I had a similar experience recently. My around town mileage dropped from a very consistent 16.9 to 14.8 in one tank. I use Power Service (Grey bottle) additive every few tanks, but had not used it in 4 fill ups. I figured I had nothing to lose, so I gave her a quadruple dose of the stuff. I drove it about 20 miles and then let it sit for 2 weeks while I was out of town. When I started driving it again, the mileage was 17 and has remained there.

My guess is a dirty injector. Maybe I should be more diligent about the fuel additive.

SCA that was were I was leaning, I don't have any CEL's so I thought I would give it a shot on here first. I will clean the air filter and replace the fuel filter this weekend. I also use Stanadyne performance formula every tank so I hope I'm not having injector problems. Thanks for the replys guys.

It also helps to reset the DIC every once in a while. If you drive with it for a long time and don't reset it, it will continually go down. Dad had that trouble too. Just replace the filter and try some cleaner. I ran some Lucas in mine and it came up a little. I need to get some and run it all the time. I think it was like $8-10 a bottle and it would last prolly 5 fills.

Ryan

My truck just came back from Chevy they had to replace the EGR (17K miles) the truck feels much better but I havnt put enough miles on it to get accurate milleage yet. I used to average 16+ plus but it had suddenly dropped to 11!!

P.S. They also reflashed the ECM with a newer code...

Well I had the truck into the dealer yesterday, they could not find anything wrong. They said the EGR was working properly , all the injector numbers were right on the money, and I had all the latest ECM updates. They checked the code history and it's never thrown a code they said, they were stumped and I'm stumped. Anything else it could be? I replaced the fuel filter this weekend and checked the air filter, it's clean. Thanks guys.

How is your fuel filter? When mine got below 20% the milage went in the crapper. Changed it now I am back up where it belongs.;)

I replaced it over the weekend but no change.

How is your fuel filter? When mine got below 20% the milage went in the crapper. Changed it now I am back up where it belongs.;)

Ditto!

Tire pressure? Draggin a brake?

I dont know how you got 19 to begin with. My truck has lost about 3 mpg but I also just put on some 33" Toyos and a leveling kit. I used to average 16 mpg on stocks (i dont have a fancy calculator dash, I used the old fashion hand held calculator) now I average mid 11's...

Do you guys that go to bigger tires account for that when you are trying to figure milege? Just for fun I tracked my milege with my GPS and found that with my tires, my odometer is off about 10%. (just like my spedo) Meaning I have traveled 10% farther than my odometer shows, so when you calculate mileage you should adjust for the extra milege that you have actually traveled and I doubt your MPG has dropped as much as you think.

Do you guys that go to bigger tires account for that when you are trying to figure milege? Just for fun I tracked my milege with my GPS and found that with my tires, my odometer is off about 10%. (just like my spedo) Meaning I have traveled 10% farther than my odometer shows, so when you calculate mileage you should adjust for the extra milege that you have actually traveled and I doubt your MPG has dropped as much as you think.

:exactly:
Big wheels and tires change the effective final drive ratio which will drop your mileage slightly, but the biggest drop occurs because the speedo is inaccurate (on the low side). I guarantee most people with larger wheel/tire combos that complain of poor mileage aren't doing as badly as they think.

I am having the same issues as MudMaster. I was getting 16.5 -17 gallons before 15,000 mile around town. Shortly after it went over 15,000 miles the mileage started to decrease and I am averaging 13 - 14 gallans, I now have 17,545 mile on the truck. As MudMaster did I took the truck to the dealer they stated that everything was fine and up to date. Changed oil, oil filter, fuel filter, cleaned air filter, checked tire pressure and my milage still does not get pass 14 mpg. I love the power but I thought that the mileage should be getting better not worse!

Do you guys that go to bigger tires account for that when you are trying to figure milege? Just for fun I tracked my milege with my GPS and found that with my tires, my odometer is off about 10%. (just like my spedo) Meaning I have traveled 10% farther than my odometer shows, so when you calculate mileage you should adjust for the extra milege that you have actually traveled and I doubt your MPG has dropped as much as you think.


I lost my mileage before I put the 265/75/16 tires on, I have only had these tires on for a week and I lost the mileage 5 weeks ago. Tire pressures are good and I don't think I have a brake dragging but I will check that, thanks.

I know that the "roll out" gear ratio is changed by tire size but I only went to 33" and according to police radar my speedo is off by only 2mph. I havnt done the calculation but im betting that doesnt account for 5+mpg!! :cool:

My truck just came back from Chevy they had to replace the EGR (17K miles) the truck feels much better but I havnt put enough miles on it to get accurate milleage yet. I used to average 16+ plus but it had suddenly dropped to 11!!

P.S. They also reflashed the ECM with a newer code...
My truck has never been flashed.......did you notice a difference in response with the reflash? My last trip showed a 2-1/2mpg drop from previous trips, but I did travel faster and with the AC on. Curious to here what your mileage is with your next fill up

My truck has never been flashed.......did you notice a difference in response with the reflash? My last trip showed a 2-1/2mpg drop from previous trips, but I did travel faster and with the AC on. Curious to here what your mileage is with your next fill up

I just filled up the other day after towing my new 24ft hauler around and got 10.5mpg which included a steep up hill for about 5 minutes at 3/4 throttle.

As far as throttle response it doesnt seem any better, sometimes even worse maybe...:mad:

We wouldn't be getting winter blend already would we?
I noticed something similar. I always fill up at the same Valero. Noticed the drop for two tanks. Went to a Shell the other day and it went back to "normal"

We wouldn't be getting winter blend already would we?
I noticed something similar. I always fill up at the same Valero. Noticed the drop for two tanks. Went to a Shell the other day and it went back to "normal"

Uuhhh...leave the truck idleing a little more then usuall?? Put your foot in it a little more?? :cool:

I dont know about other states but B5 is in a lot of pumps around here. If you dont realize it, that might effect things. Not sure if 5% is enough to make a milleage difference, but B20 prolly would be noticeable...

Uuhhh...leave the truck idleing a little more then usuall?? Put your foot in it a little more?? :cool:

I dont know about other states but B5 is in a lot of pumps around here. If you dont realize it, that might effect things. Not sure if 5% is enough to make a milleage difference, but B20 prolly would be noticeable...

That is the funny part. We have a BIO plant at West Point (not 30 min away) and you can't find a BIO delear within an hour at highway speeds. Everything around here is normal #2.

Oh and to answer your question.....Nothing has changed. I drive for as much mpg's as I can and do not idle unless I'm in traffic.

HDpullingpower (http://dieselplace.com/forum/member.php?u=48567) vbmenu_register("postmenu_1987460", true); how did you get the 20% figure on your fuel filter rating?