Trying to see if someone can shine some light on an issue Im having with a pickup truck.


Its an 09 Sierra Denali, with a whipple, stalled, and cammed.
Back story of this truck is, apparently it was originally cammed, stalled, and tuned.
After some time, they slapped a whipple blower on top of it and never had it retuned.


The truck now, idles okay, drives "okay" under normal conditions, but when I step on it, and then let off, the rpms come back down, but the truck wont drive.
Its as if it goes into neutral, and the only way for it to engage again and actually drive, is if I slow down till about 15 miles an hour, and then it starts driving again.


There are no signs of rough gear changes, or slippage that I know of, its only when I step on it.


Ive had a couple shops give me some hypothesis on the issue, some think it needs a tune, but I think the tune might be locked up by the previous tuner, and idk who that is. And some think the trans needs a tune or something along those lines.


Anyone have any idea what kind of issues I might be looking at?


Thanks!

 

Stuck valve in the valve body....

 

How tedious would it be to get this fixed, or even fixing it myself?

 

If it is a valve, get a good used valve body from ebay or something.

The bigger question is if its a VB issue, whats causing things to stick? Clutch material, metal? You got a ton of power going through that trans and an unknown history of abuse. 6l80e are picky about tuning when you're hitting them with a ton of TQ.

I'd try to pull codes first, then maybe get a shop with tuning software try to log the issue when it happens. Pull the pan then to see what you find. My gut says be prepared to $$ out for a total rebuild. That trans has had a haaaard life

 

Find snap on dealer get special torx ep10 socket, drop pan, filter, disconnect electrical connector, drop valve body after remiving 6 bolts separate all the parts of valve body.... Check valves for sticking or hanging up, screen on tcm for punctures, etc...go to dealer get new valve body(probably the upper portion) reinstall all bolts to 71in lbs... Reinstall tcm/vb assembly... Not sure if there is a fix for the valve body halves on these yet or not....

 

So would I need a rebuild or not?
Considering im able to replace the VB myself?

 

Hard to say, if theres metal and a bunch of fristion material in pan, or if you can see damage on the 3-5-R housing or the other reluctor you can see through the case when valve body is off... Then yes, but it sound slike a sticking valve i just had a camaro yesterday would after accelearating to around 50mph and coming to a sudden stop, when you started again it would downshift violently and barsically bark the tires... Ended up being both of the valves for the 1-2-3-4 and i forget what the other valve was but wasnt letting it kickdown and had no engine braking at all.... Put the upper vakve body in it and worked fine..... 6l series transmissions are a cake walk to rebuild..... No bands and the clutches fall together a hell of a lot easier than the 4l60/80 do.... Biggest this is the snap ring from hell right in the center of the case....

 

Sounds good boss.
Ran into a video on a Camaro forum where a guy shows the disassembly of a 6L80, doesn't seem to hard aside from that snap ring.


Had the truck dropped off today at Circle D, gonna see what they tell me.

 

6l80/6l90s have cheap checkballs in the valvebody...ive had a lot come in with a checkball stuck to the separator plate causing a lot of issues..just had a 09 denali in last week that wouldn't move forward at all and all it had was a stuck checkball..pull the pan first to inspect for any clutch material..

 

Metal or torlon?