So i finally got a chance to take the Sierra out to the garage where im gonna be pullin the motor (which is about an hour away) and on my way out there the truck was ****** screamin. Granted I do have a 4000 stall speed ive never seen it that bad, it almost felt like it wasnt shifting into overdrive. Recetly i posted that i was getting a code that my syncro was stuck due to the stall speed beings o high... which ive determined the code just needs deleted and never did it cause the Sierras been parked. Anyways do you guys think this is a result of that code or is it just the converter and i never noticed it before???

im running

factory 3.73s
SS4000 converter
255/60/17 = 29.04" diameter
built 4L65E

 

sounds like the converter might not be locking

 

I agree...converter not locking up.

 

def. the converter not locking up man.

 

how long did ya drive it..when its damn cold outside sometimes i gotta drive mine 6-8 miles before it will lock..my 40,000 gvw cooler dont help that

 

Hell it doesnt even sound like it went into overdrive.

 

I would say the converter didnt lock up. I see your in PA and its definatly cold here, You do know the engine temp must get above 140 degees before the PCM will allow lockup?

 

Really? That is a good thing to know! No wonder my MPG sucks most of the time, but truck is barely warmed up by the time I get to work (I only live 5 miles from work).....

 

3500 rpm is in 3rd gear.

 

yeah i think it's not shifting into OD. even with a 4K converter i don't think it'd be that high in rpms at 70mph if it's just an unlocked converter.