GLE wierd shifting.

[scubabri]

Ok, if I'm in D or 3 and I'm going down a hill, say I dunno 50 mph, so my foot is off the pedal, when I slightly tap the brake pedal, just the slightest touch, my rpm drops about 500 rpm. I can feel that its almost like the transmission has disengaged somehow.

Makes it very challenging to use the engine to help braking going down a hill for when I even touch the brake pedal, I speed up due to the lack of engine resistance.

Also, does the APP control shifting? I've noticed that when in cruise control and I start to climb a hill, I will downshift, whereas with cc off, I almost have to floor it to keep it down shifted. This was something with the stock chip that always annoyed me.


Any ideas?

 

[Acesneights1]

Mine does that too. Normally with stock program the ecm makes the TCC unlock right away. Heath's tune makes it hold a bit longer. it feels weird at first like something is wrong with the trans but you get used to it.

 

[NVW]

As Kenny said, it's normal.

 

[TMHark]

My stock tune would go to "coast" almost immedately when letting off the throttle. Great for mpg, but hard on brakes

With the Kojo tune it feels even more like this. When you let off there is a very brief "surge" and then free wheel (almost feels like you threw it in nuetral)

So I've never had any engine braking of any kind in this truck

 

[great white]

Sounds like the boys have been messing with this table or one of the others in the tune:

TCC disengage with brake application is a "survival mode" of the TCC. You can either use engine braking of you can keep the TCC locked up (depending on your defined parameters), not both.

Brakes without disengaging the small "bands" in the Torque converter that it uses for lockup would quickly destroy the friction material.

Just the way it has to be....

 

[Matt Bachand]

Mine use to do that too, but something with my brake switch under dash approaching failure prevents this from happening anymore and I like it that way.

It started when trying to diagnose why my high idle stopped working, Brake lights work, and when I wiggle wires underneath the brake switch it engages high idle as it should.

After noticing this, I noticed that when I hit the brakes my transmission does not 'freewheel feeling' down to 500 rpm like it did before.

This leads me to believe there is a way to do this intentionally.

I have a really steep offramp off a highway exit that I use very often. Being able to leave it in 3rd and hit the brake without it freewheeling (for lack of better word/feel) is much more satisfying.

Been this way for about 20,000 miles or so.