SilverSquared

I have a transmission (4L60) in my 02 Silverado. Its behind an 05 LQ9. The transmission doesnt want to shift from 3 to 4 at wot.
I have to let off 100% for it to shift. If Im not wot going in, it's fine. I have a tune on it via HPTuners and my tuner is trying to see
what's the issue. It did it well before the tune was done. Any advice....without the 4 pages of symptoms that dont apply to 3-4 shift?



Instead of editing the original...it is 2 to 3, NOT 3 to 4. I went back and checked multiple times just a bit ago.
All from a dead stop to make sure. My issue lies from 2 to 3, at 75mph.

MaroonMonsterLS1

The only thing happening during a 3-4 shift is the application of the band. So it makes it easy to troubleshoot

First make sure the pcm is actually commanding the shift. You can watch the solenoids with a scanner.
Typically issues that come right after a tune aren't a fluke.

If it IS commanding the shift, Then you have a mechanical issue. First thing to do is attach a pressure gauge and see what the pressures are doing before/during/after the shift.
If you make more power after the tune it could be making enough power to slip the band now. If it shifted fine 3-4 at WOT before the tune, i doubt the band was that marginal but I suppose it's possible.

03sierraslt

iTrader: (22)

So at what speed does your WO 3-4 shift occur?

MikeGyver

iTrader: (5)

He must be going about a zillion mph!

SilverSquared

I'll have to go back and check, under 90mph. I will get onto that tomorrow. BTW...Nice color for the 109s. They looked killer in white, I had a K6 Black.

It did this before the tune, so Im not 100% sure whats going on.
The transmission is new as of late April. Being it's under warranty still I will bring it in for a checkup.

I'll let my guy know to check what you said

FFDP

iTrader: (2)

What gears is this thing running??

Depending on that it's normally the 2-3 shift that is somewhere between 75-88mph give or take. 2nd gear is really long in a 4L60e and 3rd gear should go well over 100mph before you ever need to shift into 4th gear.

03sierraslt

iTrader: (22)

What rpm do you shift at? That doesn’t make sense for the 3-4 to happen at that low of speed at wide open. I’ve never done a wide open 3-4 shift ever.

MikeGyver

iTrader: (5)

I’ve never done a wide open 3-4 shift ever.

SilverSquared

Im an idiot that cant count.
Its 2 to 3 at 75 mph.

Going read up on issues for 2-3.