[Prostar8.20]

I'm not sure what gear the EVO by passes but I've read and can feel it do it. I think this is silly, it almost has the feeling of bogging the motor and certainly can't be good for the tranny. Is there anyway of getting rid of this feature?

 

[dmaxhd]

So set your display to show Gear selection so you can see what it is doing. My guess it is when it is shifting from 4th to 5th and just as soon as it is shifting your torque converter is also locking up. When you are not using tow\haul 5th gear is when the converter will lock

 

[Zick]

So set your display to show Gear selection so you can see what it is doing. My guess it is when it is shifting from 4th to 5th and just as soon as it is shifting your torque converter is also locking up. When you are not using tow\haul 5th gear is when the converter will lock

Yup, just set the display to show gear selection. Mine goes through all the gears just fine. Some seem real quick though.

dmaxhd, does your TC lock in 5th gear before going into 6th? Mine will only lock in 5th only after it locks in 6th and then I slow to where it downshifts into 5th.

 

[dmaxhd]

Yup, just set the display to show gear selection. Mine goes through all the gears just fine. Some seem real quick though.

dmaxhd, does your TC lock in 5th gear before going into 6th? Mine will only lock in 5th only after it locks in 6th and then I slow to where it downshifts into 5th.

Zick, depends how hard I am in the throttle. In non tow\haul at around 45mph depending on the conditions is the sooniest mine will lock in 5th gear. Most of the time my TC will lock in 5th before it goes to 6th and when it does it stays locked

 

[Zick]

Zick, depends how hard I am in the throttle. In non tow\haul at around 45mph depending on the conditions is the sooniest mine will lock in 5th gear. Most of the time my TC will lock in 5th before it goes to 6th and when it does it stays locked

That's strange. Mine will not lock in 5th before it goes into 6th no matter how light on the throttle I am.

Looks like I'll have to check into this, I'd really like it to lock sooner in 5th for better mpg for when I'm going 45-50mph.

 

[CPacetti]

Probably a silly question, but what does it mean for the torque converter to lock up? What kind of feel do you get?

 

[JoshH]

My truck almost always locks the converter as soon as I hit 45 mph. Sometimes it occurs at approximately the same time as the shift to 5th gear making it seem like it shifts twice.

The torque converter is a fluid coupler. It allows you to sit still in gear and not kill the engine. Because it is a fluid coupling device it will not transfer 100% of the power coming from the engine to the transmission. There will always be some slip in the converter. The exception to this is a locking torque converter, such as the converter in our trucks (and most all GM trucks since the early 80s). There is a clutch in the converter that engages at a predetermined speed/gear/throttle position combination. Once this happens the engine is solidly connected to the transmission. When the converter locks it may feel like a shift, depending on how much throttle you are giving it, and you will notice a drop in engine RPM.