What can i do to up my fuel mileage? Its a 97,reg cab,long bed,V6,5spd,3.08 gears, 265/70/17,2 cats removed, 2 cats replaced w/ high flow ones,vortech muffler and full length "normal" tail pipe. I do almost all highway driving at speeds between 65-70. Any performance would be a pluss too. BTW truck has 185K engine replaced w jasper at 150K..............HELP gas is killing me i'm spending almost $200 a week

 

buy a Honda Civic

 

No... those are a waste too... buy a bicycle.

 

No sugestions? I'm only getting like 15mpg

 

Try driving 65 in 4th as a test - see what mileage that gets you. 3.08's are pretty steep gears for a V6, especially with oversized tires. Is your speedometer/odometer recalibrated for the big tires?

 

The spedo is not recalibrated for the bigger tires but i do the math and they are 8% larger in diameter

 

glc why would you drive around in 4th at that kinda speed??

 

As a test to see if it gets better mileage - it just might. Remember - he has 3.08's and oversize tires. At 65 in 4th he will be doing 2100 rpm, in 5th 1700 rpm.

 

the only thing that i can think of is that you can consider changing your belt driven cooling fan to an electric fan but mayb u should do some research first because this will free up horsepower which means that your gas consuption might increase but mayb it will help your gas i really am not sure

 

well i just filled up today.381.42 miles X my 8% tire difference= 411.93 Total gallons of gas was 24.9. 411.93\24.9=16.54 Thats an all time high!!!! Never used 5th(od) not once. Once out on the highway i just set the cruise. my trip consists of 45 miles of highyway and 5 of some traffic lights each way. I may have been able to do better putting it in 5th going down hill. I'm going to try that this tank.

 

By the way. How can i recalibrate my spedo for the tire diff. Can i change it back if i put 245's back on?

 

If the tires are 8% larger, then your speedo will be that amount off. For a 65mph speedo reading, should be doing about 70, for 70mph speedo, will actually be doing 76.

Don't know about your generation truck - the newer ones can be reprogrammed for the different tire size, the older ones involve a speedo gear change. I just put a sticker on the speedo to remind me how far off it is, then adjust my speed according - usually just go about 5mph below the posted limit on the highways.

Slowing down is one option, but it will cost you time. Once you get over 60mph or so, mileage nosedives with speed.
It appears that the 4th gear thing is working out for you.
Lower profile (smaller) tires will decrease the wind drag somewhat, but won't save enough to justify buying a set of smaller tires.
Perhaps one of the many tuners available has an 'economy' profile.
Make sure you're not hauling around extra weight that isn't necessary.
Tires at the correct inflation.
Engine is in good tune, no active fault codes.

By my estimates of the numbers you've given, you're putting on somewhere around 900 miles per week. Don't know that you're going to get a great deal of relief, but I would think the truck should be getting at least 20mpg???

 

You can do it with a lot of the hand held OBD readers and/or programmers like the XCal.

 

I figured that 60 on my spedo is approx 64.8 in reality . I bought this truck figuring 20 plus on the highway.I got rid of a probe gt that i was averaging 32 but i couldnt put anything in the #H!+ box

 

3.73 or 4.10 gears. Maybe 3.55s are a decent combo...

I almost guarantee that even if the speedo was recalibrated, that 4.2L is running way too low RPMwise out of its peak powerband to run efficiently for you. You don't have a diesel.

I am quite sure you have to mash the go pedal to get up to speed and if I'm running ~1300 RPMs at 55-60 MPH with 3.55s and 255/70/16's, you're probably not doing much more than idle speed while trying to maintain speed. That's awful and it's lugging the engine, I bet.

Regear and you win. Skip the fans and all that other jazz that was mentioned, that's not the problem. Never was.

Case in point: You stayed out of OD and your MPGs went up.

There.