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Discussion Starter #1
I have a 99 that I believe has a little bigger after market exhaust and a K & N air cleaner other then that it it stock. My mpg is only about 16 and most of that has been 50 mile trips at 65-70 mph . Is there anythiong I can do to atleast get it to 20 mpg without alot of add ons or what are your thoughts? I jsut got the truck so I am new to the cummins thing, Thanks
 

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Get a bigger exhaust, a 4" turbo back is perfect for a lightly modified/stock truck. Use 2stroke oil at a 1:128 ratio. If you want look into diffrent chips. Or check out Mopar Man 1973's stuff he has a full page devoted to his trucks.
 

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atleast get it to 20 mpg
Well first off, remember that your truck weighs 7,000lbs and 20mpg's is a lot, but not impossible. Second, how long have you had it? I'd check the fuel filter for sure, maybe search the tech articles for MAP sensor cleaning? How's your tire pressure? :popcorn:
 

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what he said; check out mopar1973man's stuff...:thumbsup he seems to have the juice on good mpg's...
 

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yes 3.55 gears, I have had it a mounth, and yes I need new tires but they are up and I was going to try the 2 stoke oil, I think it has atleast 4" exhaust on it now but I will check, I ahve no idea of what chips to check out but I will, thanks
 

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Just to chime in.. mine's a 2WD auto with I think 3:55 gears. I have a 4" turbo back exhaust with a 4" resonator and an donaldson like muffler with a block off plate in the center preventing free flow. I had a BHAF on it and all my filters and oil change were new.

I get 16.5-17 in town and 22 hwy.

Since then I have put the stock airbox back on minus the rubber boot that goes into the fender to allow a bigger opening for air to come in. That didn't have any effect on mpg that I can tell.

Now I put an Edge EZ on. Level 3 worked out to about the same mileage with better performance. This tank I dropped it down to level 1 which is still way better driveability than stock, and it looks like I'm going to get a couple more mpg. Maybe 18 in town and 23-24 hwy?

Oh yeah, brand new tires 50psi front, 70psi rear and 1oz per gal two stroke in every tank.
 

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Like stated, better intake, bigger exhaust (if not already 4") and a chip or programmer that does timing. Then drive like a grandma.
 

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Grandma drives like a bat out of hell. Grandpa on othe other hand drives like a snail
 

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Oh yeah, brand new tires 50psi front, 70psi rear and 1oz per gal two stroke in every tank.
just a thought..unless your bed is full of stuff (weight) you might want to reverse your tire psi, as the front of the truck is waaaaay heavier than the rear, I haul 0-2200lbs every day (intown courior) and I found 60psi front &back works for even tire wear, If I was not hauling weight I'd have the rear at 40psi (and fronts at 50-60psi.)

I've found with higher rear tire pressure the center of the tire wears out leaving lots of tread depth on the edges of the tire, another note is if you use the reccommended tire pressure guide inside the drv door, you have to keep in mind that is the tire pressure with the truck FULLY loaded
 

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just a thought..unless your bed is full of stuff (weight) you might want to reverse your tire psi, as the front of the truck is waaaaay heavier than the rear, I haul 0-2200lbs every day (intown courior) and I found 60psi front &back works for even tire wear, If I was not hauling weight I'd have the rear at 40psi (and fronts at 50-60psi.)

I've found with higher rear tire pressure the center of the tire wears out leaving lots of tread depth on the edges of the tire, another note is if you use the reccommended tire pressure guide inside the drv door, you have to keep in mind that is the tire pressure with the truck FULLY loaded
Good tip, thanks. I didn't realize that was loaded pressure. I might lower the back to 60.
 

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definatly check the fuel filter. and throw a can of sea-foam in the fuel filter housing and one in the tank too. made a big difference in my truck
 

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Smarty is a good chip for fuel milage,keep it on fuel saver
 

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Get a bigger exhaust, a 4" turbo back is perfect for a lightly modified/stock truck. Use 2stroke oil at a 1:128 ratio. If you want look into diffrent chips. Or check out Mopar Man 1973's stuff he has a full page devoted to his trucks.
what he said; check out mopar1973man's stuff...:thumbsup he seems to have the juice on good mpg's...
Thanks guys for the great comments... Here is my page on how I'm pulling 21.7 to 23.3 MPGs...
Better MPG's

definatly check the fuel filter. and throw a can of sea-foam in the fuel filter housing and one in the tank too. made a big difference in my truck
OMG! :thud: That is the absolute wose thing you can do to the Cummins fuel system. You just wash out all the lubricate in the IP pump and injectors! 2 Cycle oil is much healther than that poison (Seafoam)! :thud:If you need injector cleaners you need a better filter system (2micron) like whats on AirDog 150 or FASS 150...:w:

Smarty is a good chip for fuel milage,keep it on fuel saver
Smarty is good... But Even a Edge Comp on 5x5 can do the same. Just keep your foot out of the boost and pyro and high numbers will happen...:w:
 

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Discussion Starter #16
thanks guys, I am going to study all that and see what I can afford to do to it, I have a lot of learning to do but I am excited about that, Thanks again and keep the suggestions comeing I am sure others could benifit as well.
 

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clean or chg map sensor this worked on mine then the cps went out changed it out and got 2mpg more now up to 20mpg as long as i keep the foot off the floor with fuel the price it is now it is much easier to keep off the floor and drive like a sensible madman
 

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you have to keep in mind that is the tire pressure with the truck FULLY loaded
I didn't realize that was loaded pressure.
This was on Car Talk a few weeks ago, they had some physicist professor as a guest. Your tire pressure doesn't change when you put a load on. Just like it doesn't change when you put your truck on jackstands. I mean, yes, theoretically it does, but its less than 1 psi so it doesn't justify filling them differently.
 

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The tire pressure may not change (not sure I understand that theory) but the footprint of the tire certainly does! so higher pressure on the rear with no load will wearout the center of the tire, and the reverse is true too low and the outter edges will wear. sooo on an unloaded truck with 50 front 70 rear you gonna have issues.
A few years ago, I was on a course the Military ran for its Vehicle Techs. They had a Michelin Tech come and explain theory on Military tire stuff, (all Canadian Military pattern Veh have Michelin tires)any way he explained that they found fuel tsp trucks were having braking issues mostly when they were empty,(meaning they could not stop) the drivers are susposed to inflate/deflate depending on load, but one one does,and it was not practical so what fuel companys do now is when the truck leaves the refinery with a full load. it goes to its further most delivery first then it drops fuel at different stations along his route. this way by the time the truck gets back to the refinery it has travelled the shortest distance while it was empty. he had a couple of photo's of tire footprints empty and loaded with the same pressure, the empty footprint was smaller than the size of a hockey puck, while loaded was 4-5 times larger, next time you see a semi locking/smoking his tires when he brakes, you can bet his truck is empty
 

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dont drive it! I get killer fuel mileage just watching it sit.
 
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