I realize that the computers do this to bring the transmission fluid up to temp quicker, BUT sometimes it simply seems to get stuck out of lock-up for a very long period of time, or will require me to come to a stop and resume driving (through all gears, then TC locks up like normal) maybe that's just a coincidence though?

Sometimes while driving I can put it into Neutral then back into Drive and she'll shift into 4th and lock-up TC perfectly.

It's frustrating because I work 8 miles from my house, and even though there are a number of lights and some traffic.. there are times when I can get home / to work and it will have never locked up! It's simply horrible for my mileage, since I'm just slipping the transmission/engine for my entire commute.

Anyways, I remember (once upon a time) seeing information on a service manual about requirements for TC lock-up. It listed temperatures, time periods, and driving speeds.. very interesting, unfortunately I can't find it in RAVE (you'd think it would be in the "description and operation" of the transmission, but it's not.

 

FWIW: I know it is temperature dependent. I work 5 miles from home. The past 3 years I have noticed an interesting tend. Whenever the outside temperature is above, say, 40* F, the torque converter locks within a mile of my departure, corresponding closely to the time when the engine reaches a certain temperature. However, when temperatures get down to the 20's, the torque converter doesn't lock until I'm much further in my drive, sometimes almost 1/2 way home.

I leave my HVAC on full auto, and usually when the mode switches from defrost to blend (based on whatever algorithms the HVAC computer uses to determine efficiency) the torque converter locks shortly thereafter.

 

Have you tried just letting it warm up in the morning for 5-10 min before leaving for work?
I agree with lordmorpheus, its a "this time of year" thing.

 

So i was just about to freak out on this one as my disco wouln't go into its highway gear...i would be driving down the highway and it would be running at really high RPMs and killing my gas mileage...after about 5 miles it would kick into the correct gear.

Glad i logged on...thanks for the post i will sleep better tonight and let the car warm up longer in the AM.

 

With 154K on it, I'll bet it is lacking on maintance and a little gummed up. How often do you change your ATF? At your mileage, it should be every 20,000 and a can of Lucas to keep the valves from sticking.
As for the lock up, once the ECU sees the engine at the 190 degree mark it will allow the t/q to lock up, and usually just above 3000 RPM's.

 

It's been pretty cold here lately (~10 to 15*F), and I've noticed this too. My commute to work is 90% city, so between the tranny not locking up right away, and me having to lock up the CDL to get through town, my mileage has been less than stellar to say the least. My new tires need to hurry up and get delivered...