valve adjustment and mileage

[dustoff]

my gas mileage has never been as good as i thought it might be... best on the road had been about 17. 5... . now its down to about 15 on the road and i was wondering how much effect on mileage out of adjusted valves would have... . does valve adjustment have a big effect on mileage?? thanks

 

[Cooker]

I agree your fuel mileage seems a little off. Is this all highway or all city driving?



Have you changed tires sizes recently and forgot to correct mileage for speedo error?



How about fuel filter/air filter, have they been replaced recently.



Maybe you timing has slipped?



Do you notice if your top boost or EGT's have changed, perhaps you have an intercooler leak.



I know this doesn't address your question, but these are just a few other things to consider when it comes to fuel economy.



-Ryan

 

[Jim Fulmer]

Dustoff

Look at our combos and how similar they are except you have a #6 and I have a #8. I get 19 around town with fast highway driving and 21 this weekend on the highway at 70(2k rpm) so your mileage is a bit off.



Jim

 

[dustoff]

cooker... . it is mostly highway driving... i religiously change filters at 4,000 miles and always check intercooler connections... boost and egt have been steady all along... the previous owner stated he got 20mpg, but i have never seen that... tires are not larger ones so i figured it must be either the valves or possibly the timing... . it has plenty of kick @ss if i get into it, but mileage has never been that great... . thanks

 

[Howard Durand]

Dustoff,



I think the previous owner was stretching the truth a bit.

I averaged my total miles per gallon over the entire time I have owned my truck and it comes out at about 17.

I get between 13 and 14 towing at a gcw of about 15,000#



I have never seen 20 mpg. The highest was just a little over 18.

I attribute that to the fact it is a 4X4 and auto transmission.

I also have a canopy that is cab high in front and increases in height toward the rear.

 

[RBrunson]

Milage

I just made a run up I-5 and back home, about 250 mi. at 70-75 mph. 22. 6 mpg. I have heard of others getting better than that with mild mods. This was the first good test since I installed the DD2 plate. Before (two years of driving) the most I ever seen was about 20mpg.

 

[Dennis Garrett]

Don't forget to figure in odometer error. You'll want to check it for about ten miles. & see what it says. Make sure you find a place where the mile markers are correct. Mine says about 9. 85 for ten miles traveled, but when I first got it , it was about 12% off. Had to regear it go get it this close. Makes a big difference when trying to figure out fuel mileage.

 

[Steve Roseman]

Dustoff, One of the biggest factors(besides pulling trailer)that I've noticed affecting my mileage is where I buy my fuel. Some stations just seem to have a better quality fuel, it might not hurt to try around a little.