6.4 weak 3rd gear / xrt pro

[liesel]

bbbbbbbbbbbbbbbbbbbbbb

[torqueshift]

Originally Posted by liesel

2008 6.4L; 36k miles; tuned with xrt pro, s&b, dpf/doc delete pipe for the past 12k miles or 1 year

anybody else have this experience. feels the same now as it did stock: 3rd and 4th gears feel like a dog until 4th + tc lock on s1M or s1L. Not as bad on default hot +250; more noticeable on mild +80; most noticeable when stock a year ago.

but why does this thing feel awesome in 1st and 2nd, weak in 3rd and 4th, and then back awesome again at 4th + tc lock and 5th? when it hits 3rd it feels like a lot of stuff's happening under the hood--it clatters loud like it's just kicking butt, but it doesn't translate into more power at the wheels. no smoke, no codes--just feels cheesy. i can't wait until it hits 4th + tc lock, because it feels like it should--lots of smooth, quick power when I push the accelerator.

haven't found any related posts. most comments are by the diesel guru guys. i'm just a regular guy whose level of involvement entails dpf delete, tuning, air box install, own oil and fuel filters changes, and putting diesel kleen in at fill-up.

i can tell you that on +250 s1L i can get 19.2 mpg IF i keep it under 68 mph (about 1850 rpms) with 3.73 rear end. it took me a while to figure that one out.

about to take the 5000# rv, wife, and 4 kids on a trip just in time for rising fuel prices, no doubt, and want to know what's the best xrt pro settings. as of now i plan to use +80 / s1M. pretty sure i'll be giving up some mpg's i normally get on the +250, but don't want to sh**wreck the truck to gain a couple of mpg's. any advice?

thanks...i would know even less than i do now about diesels without this forum.

i was just reading old trans post...when i read yours....

have you solved the 3rd to 4th problem????

i was having a HARD 3rd to 4th shift in S1L & S2L

my trans fluid was a little low...so i added 1 qt of of the Motorcraft LV
3rd to 4th got firmer ...i checked the trans dipstick after running he truck...i was in the HOT range...but there was an 1/8th of an inch available to still add fluid...so I did.. and the 3rd to 4th shift got even better (softer and firmer)

my MPG's are rotten in S2L...but I'm not a fan of the 4th gear TCLockup
I got good MPG's in S1L...but again that 4thgear TCLock was not for me.

I have 38K on my 2010 and I run a Mini Maxx on the "HOT" power setting.