some advice
 

my truck is getting really bad gas mileage. ive replaced all spark plugs, all coils, intake manifold, pacesetter longtube headers, sct x3, spectre CAI, no cats and and flowmaster muffler. pipe is all 3 in. now i have been getting really crappy gas mileage. like 170 miles and used 3/4 tank. i have the 25 galllon tank. now since i have these things do i need a good tune? and will my little tuning be fine? also i have a lift and tires and a big custom bumper. please let me know what you might think it is. also how many miles per tank do you guys get?

What is your MPG (hand calculated, not the what the scanner says)? You know that not all gas gauges are real accurate and they differ truck to truck? Going by xxx miles for this much on the gauge is not how to figure it out.

First thought would be your O2's incorrectly reporting causing it to burn too rich. Also, 3" all the way might be a little big.

If you have codes, get them scanned and post them.

i dont have any codes. the truck runs absolutely amazing just uses alot of gas. the rear 02 sensors are deleted, and the front 02 sensors are new. im not going of mileage off of any scanner. but if i cant get 250 miles per tank im getting worse than 10mpg. also i heard 3in isnt to big for single pipe. its got longtube headers to offroad y pipe to flowmaster super 44 out the side like the lightnings

also idk if it matters but sometime in the morning when i first start it it revs real high then drops and barely wants to idle

We have close to the same truck, minus the mods. 10-12 mpg is common for me and lots of other people. Mostly city driving, short trips and letting it warm up because it's winter (not by the calendar).

Exact MPG helps to know, especially when troubleshooting a mpg issue :wink:. I mean...it's really silly to not figure it out if you think you are getting bad mileage.

My guess is yours is running too rich without any cats. Or, you drive like me and are not the lightest on the go pedal.

A custom tune would help, depending on your goals (power vs mpg) and who does your tune.

Does it ever die? How high is "real high"? Again, could be your O2's, they can cause a bad/inconsistent idle.

well i had my dad edge cts and ECOavg was 16.5 mpg i thought it was to good to be true. is there a good way to tell mpg? and i get on her every once an awhile and usually drive at 2k rpm or below

it goes to lioke 3500 rpm then drops and sputters itself back to life and runs fine. but sometimes if its real cold it will die.

You adjusted your tire size on the sct right cause if not you're going further then what the trip says since bigger tires cover more distance per revolution then the smaller stock ones

Fill up, clear trip meter, drive until near E, fill up, divide what's on the trip meter by how many gallons you filled it. Miles per (divide) gallon.