Engine/Transmission (1994 - 1998) Help - need to get better MPG

[gwizpro]

Okay, ever since I have been on this board, I have seen MPG figures that truly astound me. I'm thinking "are these figures for real". Most everyone claiming mileages in excess of 15 MPG. I am getting 10. 1 MPG on a consistent basis with in town driving. I do not have a lead foot, I do not accelerate hard and there are very little hills in my daily driving. Highway sometimes goes as high as 12MPG with tail wind (this is at 70 MPH and 2200 rpm) (55mph yields 12. 4 MPG). The Air Filter is clean and I always check it for cleanliness. I understand the fuel is different in my area during the winter and that winter driving tends to lower figures, but the mileage is the same no matter what season it is. Different bombs (see signature) on the truck have had no appreciable effect on the mileage either. These figures are also with an empty truck. I do have 4:10 gears but my mileage seems at least 30-35% lower than anyone here on these forums. WHAT are the possible reasons for this low a mileage. My signature shows what I have on the truck. Heck, just had a new complete DTT transmission installed and the mileage stayed the same. The old transmission slipped horribly. Tires are 295's. Some suggestions would be deeply appreciated. Thanks, Tom

 

[JFaughn]

Is your K&N in the stock air box ? or at least sheilded from the exhaust temps? The 4:10s are a 3-5mpg part , but can be partialy mad up by changing tire size, then what are the lubes in the drive line ? dif-transfer -thiner, synthetic , see if theres any drag , bearings , brakes ect , and this one you should like more mods , more fuel ,injectors , DVs. I've seen a lot of post were bringing in more fuel - inj, DV , add MPGs.
Just some ideas.

 

[Berrigan]

Somethings not right. You should be doing better than 10-12. 4. First verify odometer accuracy. Your tires are taller than stock. That will make your speedo and odo read lower than they should. After that look for dragging of brakes etc. Your 4-10s wont hurt your town mileage very much unless you can drive 50 or 60 in town. Im guessin 10 to 15 percent increase just with an accurate speedo. Bill

 

[jtwcummins]

I have same gears and an auto. Got new in Jan 1997. Have consistantly got 13+ MPG in city driving and about 17-18 hiway at 70 MPH. Can barely crack 20 MPG if I keep speed just below 2K on the tach, between 60-65. The Banks plate is a little less aggressive than a 10 and it is as close to the position of the factory plate as I can get it. Timing and other things are at stock levels. Under hard accel I get smoke but it is not heavy black smoke. Kinda brownish/gray.



Are you fueling to much for the way you are driving? Moving the plate forward and AFC springs make the fuel come on harder at the low end and it doesn't letup. I am interested since on Feb 1 I will be at DTT getting a trans, 3K gsk, timing bumped to 15. 5, and bigger injectors. To date nothing I have done has made any noticable difference in fuel economy, except right after I installed the power pak, heavy foot thing started and stopped when I saw the cost in fuel.

The only thing I can think of is dragging brakes if engine is smooth and not looking like a destroyer laying a smoke screen. Smoke is cool but always happening costs $$$

 

[JFielding]

Mileage Woes

My '94 just got filled up and hand calc'd 20. 4 mpg. I alway fill up until I can see the fuel in the neck so I am roughly repeating each fillup the same. That is low by 1 mpg over spring thru fall driving. Mine is a 2wd regular cab with auto and 3. 54 axle. On the hwy I drive the thing at 60 mph to keep that kind of mileage going. When I get to 70 and over I run at 17 mpg or less.



I also noticed a big problem with mileage if I ran around with overdrive locked out.



The Banks package improved the mileage about 2 mpg over stock. Your mods should have helped too.



I've got to believe that 4wd and 4. 10 axle is the major cause of low mileage compared to mine. Try a smaller shoe on your right foot too.



A gear vendor's unit would probably help. But how much fuel can you buy for the cost of that unit?



My '05 gets up to 20 mpg hwy depending on my foot. The idea of a new truck can be appealing too but again a lot of extra dough just to get better mileage than you've got now.



The ricers are great on mileage. I got 28 mpg on my 2002 Subaru Outback but it physically fell apart at 42000 miles. Thats why I got the '05 Dodge.

I get 8 to 10 mpg less but I sure got a better ride!



Lee Iococa said something like "people will pay any amount for economy". It may be that you are ok with the truck you've got.

 

[Johnstra]

I just filled up yesterday. 579 miles on 28. 4 gallons... 20. 4 MPG.

-john

 

[J Shocik]

From Gwizpro:

I do have 4:10 gears

I have the same truck, except I have the 3:54's. IMO this is the problem. When I was looking into buying a CTD, everyone told me in order to get the good fuel mileage, go with the 3:54's. I met one guy who had the 4:10's in his CTD, and he changed them to 3:54's for the mileage reason. He was getting the #'s you say you're getting. So when it came time for me to buy, I bought the truck w/3:54's and get 16 mpg in the city, close to 20 on the highway. I got 21 mpg's while visiting in Fla.

 

[burnin oil]

Make sure your tires are aired up and adjust your valves if has been a while. Many people have seen a gain of 1-1. 5 MPG by adjusting the valves! My 04 saw a 1 MPG gain airing the stock tires up to 70 PSI all around instead of 40 PSI. My 95 has 35" tires with 3. 54 gears in a 4x4 and consistantly gets 16. 5-18. 5 MPG. Most of its driving is short trips and I get stuck in traffic half the time. I picked up some MPG when I started running a little waste oil also. Do you run additives. They realy do seem to help. Only time will tell what the milage is like now I got the 10 plate installed.

 

[TRCM]

Well, I get 13-14 mpg towing 10k @ 2200 rpm, 15-16 mpg combined city/highway, and the only time I have had it on a trip long enough to verify, I got an average of 18 mpg. Highest tank was 19. 3 mpg.



I could have gotten better if I had driven @ 2000 rpm, but I was compromising between better economy and less drive time.



My speedo is off due to the slightly larger tires. I had been thinking it was off by 4% strictly from calculations, but today, I drove by one of them cop things that shows your speed, and using that number and my speedo, it is off closer to 7%.



So, when I thought I was doing 65 on the road trip, I was actually doing 69.



I am really curious now to see what it goes to when I get the new injectors in it, and the governor arm adjusted better. Maybe I'll break 20 mpg ??



Nah... not with my truck... .....

 

[Johnstra]

Well, if your speedo is off by 7% on the low side, then you're already getting 19. 26 as an average. If it's off by 4%, then you're getting 18. 72.

-john

 

[TRCM]

I wish... but the numbers, at least for the road trip, are corrected for the speedo error.

 

[Johnstra]

Aww, too bad. Just trying to help