Pause between gears LBZ

SmokeShow

Well-known member
Nov 30, 2006
6,818
34
48
43
Lawrenceburg, KY
Tony, what do you make of the idea that the truck clicked off shifts perfectly on the same tune that is now apparently defueling? Doesn't seem totally tuning related does it? I understand you can tune out any defueling if so desired but why would shift perfectly before & not now on the same tunes? You really think that's all in the tuning? Pretty wild if so.
 

jkholder09

New member
Jan 8, 2012
1,188
0
0
Maryland
Maybe loverich will chime in but could the fluid not be slippery enough and the valves sticking in the bore?
Can you watch commanded shifts and the subsequent successful stroking of the valve in the bore validated by a rapid and consistant change in tfp logic?


Sent from my SPH-L300 using Tapatalk
 

IOWA LLY

Yes, its really me
Feb 23, 2007
2,275
4
0
Tony's right. The reason it shifts fine sometimes and not others is because as the trans learns and adjust to the tune a lot of time it will start feeling slower and lazy. Especially if the defuel isnt correct. Reset the adapts and it will probably go back to shifting fine for a while....

There is so much to defuel, and the trans relearn process that most people don't understand its not even funny.



Tony, what do you make of the idea that the truck clicked off shifts perfectly on the same tune that is now apparently defueling? Doesn't seem totally tuning related does it? I understand you can tune out any defueling if so desired but why would shift perfectly before & not now on the same tunes? You really think that's all in the tuning? Pretty wild if so.



Sent from my SCH-I535 using Tapatalk 2
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
232
63
Fullerton CA
If the TCM detects slippage it will pull back timing and fuel. That is a fact. Tuning is static and doesn't change. Resetting taps is a 5 block band aid if there is a problem. It will make you worm and fuzzy for a little while till the problem comes right back.
 

GMC_2002_Dmax

The Still Master
Adjusting shift defuel is different between models, the LB7 and LLY use a combination of Throttle Based Inj Qty/Torque Limited Inj Qty/Base Tq/Main Inj with and without pilot/Fuel Pressure Base.

The LBZ and LMM have Pedal Position to desired Tq/Torque Based Fuel and No/NONE for a Torque limited injection quantity table.

There is a very specific way to adjust the defuel on an LBZ and LMM that took a long time to figure out.

If you trans shifts good at part throttle and WOT and defuels badly between say 35-80% TPS your tune is poorly written and it has nothing to do with saving the trans, at least on my opinion, does the factory tune shift like crap ???

If the answer is "that is the way it" is the wrong answer , that means, in my opinion, whoever wrote the tune has not completely figured out how it all works.

;)
 

jkholder09

New member
Jan 8, 2012
1,188
0
0
Maryland
It does take some time to get a quick shift on a 6 speed. In the middle of speeding up timing and everything else I think some guys might get the valves moving too fast in the bore and it starts to mushroom them. The coating and bore plugs only help to an extent.
Before I would say its bad tuning or anything I would put it back to stock and drive it a bit.

Sent from my SPH-L300 using Tapatalk
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
232
63
Fullerton CA
It does take some time to get a quick shift on a 6 speed. In the middle of speeding up timing and everything else I think some guys might get the valves moving too fast in the bore and it starts to mushroom them. The coating and bore plugs only help to an extent.
Before I would say its bad tuning or anything I would put it back to stock and drive it a bit.

Sent from my SPH-L300 using Tapatalk

Valve body works off of control main pressure ( 85-125 psi max ). Not much chance of mushrooming.
 

Fatboy

I need a $$ tree!!
Feb 15, 2013
75
0
0
Newnan, GA
From the note on the fluid. Could the fluid be inferior and it has taken the last 3-4k miles and has broken down and not able to provide the correct lubricity for the valves to operate correctly? If the valve is hanging it could cause a pause between shifts?
 

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
15,681
232
63
Fullerton CA
From the note on the fluid. Could the fluid be inferior and it has taken the last 3-4k miles and has broken down and not able to provide the correct lubricity for the valves to operate correctly? If the valve is hanging it could cause a pause between shifts?

If the shift valves are hanging you will get codes because they won't ground the pressure switches and give feedback to the TCM. If the trim valves are hanging; you probably won't get codes but you will have some nasty flairs and cluncks on the up and down shifts.
 

Fatboy

I need a $$ tree!!
Feb 15, 2013
75
0
0
Newnan, GA
Okay so that theory doesn't pan out. I don't have any codes or clunky shifts, just hangs longer than it should between gears. I put it on 100hp this morning and drove like a grandpa and it was pretty smooth sailing. 1/4 throttle was good but a noticeable difference than creeping. My biggest confusion is why it went from great to horrible with no codes or changes. It was overnight. Silly question but could the DSP5 switch cause confusion to the ECM?
 

jkholder09

New member
Jan 8, 2012
1,188
0
0
Maryland
Maybe loverich will chime in but could the fluid not be slippery enough and the valves sticking in the bore?
Can you watch commanded shifts and the subsequent successful stroking of the valve in the bore validated by a rapid and consistant change in tfp logic?


Sent from my SPH-L300 using Tapatalk

If the shift valves are hanging you will get codes because they won't ground the pressure switches and give feedback to the TCM. If the trim valves are hanging; you probably won't get codes but you will have some nasty flairs and cluncks on the up and down shifts.


That is what I wanted to check first mike.
You are way better at explaining stuff

Sent from my SPH-L300 using Tapatalk