Well I decided to post because the other guy is complaining about 12mpg with a 5.9L. I would be happy to get that. I have a 99 Ram 1500 4x4 ext. cab short bed with a 01 5.2L with about 83000 miles and 3000 miles on new tune-up. I just installed the motor about 4 months ago and was getting 11 mpg before I adjusted the fuel sync. I was about 7 degrees on the fuel sync. and adjusted it to the recommended 0 degrees. Now I am getting anywhere from 8 to 9.75 mpg. I don't know whether to turn it back to 7 or more to get better mileage. I don't really recall any noticeable change in performance from 7 to 0 degrees. The truck seems pretty gutless anyway, I think do to oversized tires and ****ty gears more than anything. Anyway anyone have any good ideas or maybe suggestions on how to get better mileage. Or maybe this is typical. Thanks Rob

 

What kind of tires and gears are you running?

 

+1

how is the plenum gasket,, maybe also a bad o2 and running a little rich

 

heres a tip dont open it up i got 17 high way i have an 01 1500 reg cab 8ft bed 4x4 5.9l auto 245/75/16 w 3.55 gears. that was on 87.

 

i run 87 octane always, and with my 95 reg. cab, longbox 5.2L stickshift, with a stage 1 cam and no exhaust, i can get 17 highway, 16 city....definitely need a stick for better mpg's in these trucks

 

Don't agree with that. I can't get over 13 in the city with my stick. Hwy has gone as high as 18 but that was at 62mph without stopping or wind. Typically I see 13 average. But who cares? Gas is cheaper than 2 bucks!!!!!

 

Thanks guys for the replys. I am running 285/75/16 tire size and not sure what gear, I would guess maybe a 3.55. As far as the plenum gasket it is all new. That is the other thing that I did, I installed the top end of my 99 motor just to stay away from swapping out the injectors. It could have a bad O2 senser but wouldn't it throw a code? I haven't had a CEL on since I finished the engine. By the way these mpg readings 8 to 9 are driving like grandma would drive.

 

well i do have the 35 gal. tank, so when i have to fill up, my calculated mileage is actually based on half city, half highway, so i usually fall around 16-17 mpg. the exhaust helps alot cuz it doesnt bog down, and the tonneau cover is prolly helpin a bit too, plus i dont carry any weight in the bed of the truck, so its not loaded down. it seems higher than normal, but its what i get, and im quite glad i get that kinda mileage

 

I have a 98 QC short bed 4X4 with a 5.2 and a manual trans and I get 17 mpg @ 65-75 mph unloaded and 12 mpg @ 70 mph towing a full car trailer with a car. It has 3.55 gears and LT265/75R16 tires with 139xxx original miles plus I run the cheapest gas I can find.

Will

 

So basically I have something wrong with my truck and I have to find out what it is. I think I'll set it on fire and buy a Chevy. Hell I had a big block 3/4 ton suburban and got 10 mpg and could pull and haul anything I wanted. Anyone else have any sugguestions?