my tahoe gets about 12mpg and is stock besides tune and muffler. but it is awd. my t-case has a 60/40 split or 40/60. so i drive all 4 tires all the time and you can tell. if i'm doing say 55mph and go up a very slight incline my tcc will unlock untill i flatten out then it will lock back up. it does this all the time. lke increase speed just a little or what ever. i know i can change the lock up tables but i am giving it quiet abit of gas during this so there is a reason it is unlocking. now what if i swap in a autotrac t-case where i can select 2wd will it help my mileage. and my front axle does not have a disconnect like the 4wd rigs do. so if i use a newer type auto trac that does not spin the front drive shaft all the time will it work? and will my front axle not being able to disconnect affect shift on the fly 4hi? i need to do something. when SSS people get better mileage than me something isn't right. i understand there viscous coupling does not drive the front wheel all the time unless the rear tires start to spin then it will "engage" the front end through the viscous coupling.

 

i would be suprized if swaping the tcase did anything for your mileage especialy if you didn't do the front diff that can disconect too, that stall isn't helping especialy if your lock up is coming unlocked a lot. some mileage helping ideas would be nice if anyone has any. i get 15.7mpg with my tahoe, mixed driving and only 13mpg with the sliverado. they are both stock and almost identical. there must be something wrong with the truck doesn't there? i can see the 02's switching and have done a filter and oil change with no effect.

 

well what about a 2/3 drop and some 30" tires that are alittle lighter also? i know the stall unlocking is sucking it down but i can tell its the drag or something causing the bog i have to give it a bit of gas in overdrive to speed up. but in 3rd gear at 35 with the tcc locked i can roll into the gas and it feels like a stick shift and just pulls great. but in overdrive its just a dog everywhere(all speeds). unless i'm doing like 85mph.

 

what about the SSS t-case? another question, when i build my 383 should i leave in the TT3000 or put the stock one back in? i know the 3000 would be a thrill, but would i need it being that i would have so much more low end torque?

 

Have you run a scan recently on your tune, it sounds like something is out of wack. My 04 Escalade ESV, one heavy mother, gets 15.5 in all around driving and 13+ in city only driving. Hauling my 24ft enclosed trailer with a vette in it I still get 10.-10.5 on flat terrain. After a trans tune I now get 10.5-11.0 towing.

 

is yours the AWD model? and what gears do you have?

 

Its a LQ9 and AWD with 3.73 gear

 

maybe its the extra power you have over coming the drag of AWD

 

You might look at the tune you have for the trans. Using EFILive and lots of suggestions from their forum I was able to develop a trans tune that helps in acceleration, more usable speeds on the TCC, about 25% of torque management removed, etc. This allowed me to get into OD at lower speeds without the TCC unlocking and made the "around town" mpg to increase.

 

damn I would also like what to do for mpg? cause I used to get 15mpg, then I installed a stock muffler and it all went to ****, 12-13mpg, street or highway, that was with an 87 tune.... now I just installed a magnaflow muffler, electric fans, and got an 93cot tune that feels real good in the street, I'll have some numbers sometime next week to see if that worked... I havent used the truck since I carpool with some other guys at work, I'll be using it this weekend...