BOGGING BADLY! - SOLVED

[mikez71]

So you are saying, if there is no drag down, that the converter is semi locked always?
I haven't noticed it stalling coming to a stop.. ?

Would it be noticeable in the TCC slip and Trans slip graphs?

 

[hagar]

Yeah. Trying to think of things that can load the engine down at low rpms. I am not sure with a 6l80 if it would stall the truck, i have never tried locking the converter at idle on a 6l80, but I have had a customer car with a 4l60 that had a converter solenoid fail, and it loaded the car down hard at idle and low rpms. I guess you could also do it the opposite way and turn it off while driving in commaned lockup and see if the rpms change. It would also be a way to see if the converter itself has failed. It should be a very noticeable change.

 

[hagar]

You can also try driving down the road in a safe open stretch, then pop the truck into neutral and let it coast without touching the brakes. Nothing to do with the converter, but another test to see if something in the drive train or brakes is dragging it down. You would think you would feel it acting like it has engine braking just normal driving if that was the case, but just trying to eliminate anything that can be loading the engine.

 

[mikez71]

One thing I am now noticing that COMPLETELY lines up with your theory, my TCC slip used to spike to ~400 rpms after a shift (1-2)
Now it seems to only slips 100-200 rpms after 1-2 shifts..

ruhroh.. I think you nailed it hagar!

nice looking TCC slip rpm peaks 1-2-3 shifts, BEFORE


No nice looking peaks, AFTER


Regarding TCC pressure, do you know if there is a pressure sensor or if it is just calculated?

DO NOT CHANGE regulator gain from 1.5 -> .375. Different OS, different math I suppose. .375 x 4 = 1.5.
My guess is the 2015-2018 settings retain similar actual regulator gain but with different values... (some newer settings are refinements I believe)
Wanted to give it a quick test because the TCC ramps in so slowly stock.. (taking 3-4 seconds to fully lock, feels like a light roll on surge)
Probably needed only to adjust the TCC apply ramp and not mess with regulator gain..

 

[j91z28d1]

could you just disable lock up?

 

[mikez71]

It has always been disabled in 1-3!
The light blue graph of tcc pressure is all 4th gear.

Did something get jammed up or start leaking?
Still slips around 800rpm at idle in gear. Doesn't bog coming to stop, so it's not stuck stuck..

Hopefully I'm flat wrong! (boo no 10l80 swap!

Or could it be the knock retard slowing acceleration enough that the slip looks different?

I have noticed REP mode does retard timing 15 deg as well as limit throttle to 6%.!

 

[mikez71]

So theres a missing front driverside upper motor mount-to-block bolt that ran away. And his neighbors were upset, starting to leave and go look for him!



I guess the weakling that did this (me) couldn't do any better.. or forgot to tighten one side.. or a combo. theres no telling anymore..

Did replace knock sensors since they are cheap, but I know the old ones worked, I'm not sure my new knock sensors do! (Until I finally log some knock I suppose)
I'm happy! So far so good, fingers crossed. Leaving my liners off until I finish (re)tightening everything..

To clarify, while Knock Retard went as high as -16 degrees, there is a maximum knock retard map that limits it to 10 degrees.
So the most retarded timing bottoms out at -10 degrees. What a difference!

 

[petethepug]

You could retitle this thread: “How to slow down your mother in laws truck because she drives too fast”.

 

[gooffeyguy]

So the missing motor mount bolt was causing the knock sensor to pull timing?

 

[Foggy]

So the missing motor mount bolt was causing the knock sensor to pull timing?

Sounds like it ! That would cause some noise right at the engine block
So the knock sensors would certainly pick it up and think its real knock