Pause between gears LBZ
- Thread starter Fatboy
- Start date
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.
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?
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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?
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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.
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There is so much to defuel, and the trans relearn process that most people don't understand its not even funny.
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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.
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.
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.
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Before I would say its bad tuning or anything I would put it back to stock and drive it a bit.
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Valve body works off of control main pressure ( 85-125 psi max ). Not much chance of mushrooming.
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.
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?
That is what I wanted to check first mike.
You are way better at explaining stuff
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De-fuel adjustment on LBZ/LMM trucks is very simple, and much quicker than LB7/LLY adjustment in my opinion.