8.5 is way wrong. As other have said its got to be something else. I added a flowmaster 40 - K&N CAI and a flat bed cover and got more passing power and a few more mpg. I have been away for awhile and have not been following your posts but you didnt do all this at once did u? You should have done this 1 at a time and you would have seen what mod killed you. You computer must be mixing the fuel too rich. Might want to get a code reader and check it or take it in for a inspection. Sometimes a mod can screw you but I dont see anything on your list that is too bad.

Good Luck

 

I have read the above and it is all good info but he says he is down to 8.5 this says to me he was happy with what is was before. Or I should say happier.
Anyway before I would start spending money on up grades I would see what the heck the problems is first. Something changed driving habits, tune-up issue or mechanical.
could be some of the upgrades will be in order to fix the problem I know from experience with a jeep with the 318 that air and exhaust systems can be very important to both power and fuel MPG. But in my opinion until you find out what is causing this drop in mileage you can't fix what it is?
I know these trucks are notorious for poor MPG but I was getting twice that in my jeep due to mostly my driving habits. And I was on the higher side of average but you should do a lot better then 8.5 stock unless you only have two gas pedal positions off and full on.
Alex

 

the big problem is the weight of the truck and the aerodynamic profile it has (it's a brick). I also had a jeep GC and it was getting mid 16's on average. that was with only the K&N intake kit and a gibson exhaust. I would be curious to see how it would perform with my 360 in one... I bet it would scream!

 

Grand are bricks too i hear ya on the screamer part. I took out my Full time TC for a 242 talk about smoke shows even this didn't get me much in the way of added MPG 2wd But I didn't install the new case for MPG I just wanted better control over the 4X4 system.
16 was my city hwy adverage on trips I was getting 20-21 mpg I always like the sleeper appearence of these things.
the jaw drop whe they see what it can do is always the best.
Dam I can hardly wait..
Alex

 

if you havent already found this website... check out www.krcperformance.com they have a ton of info & parts for sale... check out their dyno page!

 

You basicly went the way I'm planning in change from a grand to the RAM how do you like the change?
I'm looking at the cummins but do you feel it was a good move?

 

i had a run in with a deer in the GC, right after putting in about 1800 bux into it in the form of a low milage motor tires and a few other odds & ends. it had about 200k on it but I just got it all dialed in to go another 150k when I hit the deer...

I took the ins bux and got the truck. I LOVE my truck even though it's a pita some times. I paid cash for it but if I were to go buy another, it would be a diesel...

 

I understand that it's going to get poor fuel economy, but when my friend's Chevy 6.0 blows by me like I'm standing still and get 15.4mpg it s_ _ ks. I'll replace things one step at a time and keep you guys informed. Thanks for all of the help.

- Rick

 

I hear U man... My buddy that I work with has a yukon w/ a 350 that is supercharged.... he gets like 14 or 15.. a lot of bull... i only get 10 but my foot I think is made of 99.99 % lead.. lol

 

What size tires are you running? If your tires are taller you are going farther than the speedometer reads. My 11MPG turned out closer to 13 mpg when I calculated using my buddies mileage on a trip. His truck was stock. If the speedo is off, then so is the distance your odometer reads.....