Honestly, I have this issue myself. But I also know mine is down on power. Likely due to needing tuneup, catalytic converter, etc.

When mine was 100%, I never had any issues, and when the weather would start cooling down, the 30mph downshift to first was darn near brutal, even though it is not supercharged.

Keep in mind yours is also a 92, a year they ran no EGR. They are known for excessive combustion temperatures, and like to burn valves and heads on occasion.

Another thing too, your final drive ratio is likely 2.84, which also can make an engine in need of some help even more groggy.

Yet more good info, cool..

Ok, so if I'm following you correctly,
the car can be prompted to come out of OD AND/OR unlock the converter
by either lightly brushing the brake pedal
or completely releasing the throttle.. Correct..?

As for the momentary switch wired into the brake light switch (to temporarily kick it out of OD or Lockup on grades): Is the recommendation against it related to the Caution in the Owner'* Manual against using the 'D" range for over 5 miles? Or is there another reason?

The following quote is either going to keep me up all night or give me nightmares:
Excessive combustion temperature and the damage it causes (in other words, "lugging" - IE: exceedingly low engine rpm under load) is the very reason I am concerned about the car'* propensity to be in Lockup and/or OD at inappropriate times - IE: Pulling one of the many grades in this region.
Lugging can occur on even a very shallow grade, and flat stretches of road are the rare exception around here, you're either going up or down a decent grade 95% of the time.
This isn't a state of tune issue, as the car runs great - very smooth, plenty of pull (when it'* not in Lockup or OD). And I realize that I can't compare this '92 LeSabre to my classic cars, which feel entirely different. However, I've driven many later-model cars over the years, and none of them ever "lugged" like this.. As a truck driver I'm very aware of when an engine is "happy", and in a suitable rpm range for the operating parameters. And I'm also aware of the devastating results of continued "lugging". So this car'* propensity to be in Lockup and/or OD at inappropriate times is buggin the hell outta me lol.. But I love the car otherwise..

Honestly, now that you mention it, mine doesn't like kicking down either when it starts pulling a hill. When I start dropping speed, I usually pull it down out of overdrive for that very reason. I can give no explanation why the manual discourages it. I figure as long as the engine and transmission temperatures are where they should be, it should make no difference. The only down side is worse fuel economy, maybe that is why they stick it in there?

Yes, if you are cruising at say 60MPH and you are approaching a small incline, just gently let go of the gas pedal and get back into it. This will unlock the TCC. Depending on how much you push it down, it will either stay in 4th or, go into 3rd.

Reason I said about discouraging a switch is, if you forget to turn it back on, your going to have no TCC lockup and probably a check engine light.

to almost everyone in this thread w/OBD1: acquire BURN2 from Moates, program your own shift points and TCC lock thresholds. that'* my advice.

or find someone to do it for you, either way.

EDIT: also, the NAPA link is broken?

double EDIT: part number ATP 17783?

on every fwd gm v6 ive ever had (there have been quite a few) 50mph in 4rth locked is when you find out the plugs and or wires need replaced because thats the first trouble that pops up. feels like the engine isnt happy sorta vibratey. this is before the mileage starts decreasing because at this point your gap is significantly enlarged. that being said many big cars with sub 3 gears are alot happier running in drive, you may get better mileage if its all hills. cant see any reason why they would say not to sometimes they do that for political reasons who knows.

i have my tune setup to lock the TCC in 4th at 36MPH if my foot isn't in too much throttle... hell of a lot better than having to pull myself up to 45MPH for the converter to lock in the stock tune.

keep in mind this is a W-body with a small port 3100/4T60E/3.33 FDR. your mileage may vary (pun intended).

Good stuff in this thread. I might grab an adjustable modulator one of these days and see what that does.

My car (4T60-E, 2.84 FDR) has done the same thing since day one: approach a gentle incline at about 40 mph, then speed up to about 46-48 and watch your transmission shift into fourth and overdrive. Don't touch the gas, and you'll be back down to 40 in no time. On slightly hilly terrain (some parts of the Saw Mill Parkway, for you locals), I just keep it in third unless traffic lets me get up to at least 55.

Plenty of great info & food for thought in this thread, thank you everyone

The NAPA part# for the Adjustable Transmission Modulator is ATP 1-7783
- a NAPA nearby had 1 in stock ($24.49)

I've been driving the car and based on what I've read here the transmission is shifting perfectly normally, exactly as described on this thread.

Knowing now just what is occurring (and why the car sounds and feels as it does) and that all of it is considered normal for this transmission is a relief.

And all of the tips for controlling it'* behavior with the throttle (and brake) have been very helpful. Observing the shift points, converter lockup and OD engagement, all occurring exactly as described, and then manipulating them
using the various methods, has been fun..

I've been doing some further reading on the 4T60-E transmission,
and OD is actually considered 4th Gear (it just happens to be of a ratio that makes it an overdrive). So when we drive our cars in "D", we are essentially forbidding the trans from ever shifting into it'* 4th (and final) gear. Maybe that has something to do with the caution in the owner'* manual against doing it for over 5 miles..

4T60-E Gear ratios:

1st - 2.92
2nd - 1.56
3rd - 1.00
4th - 0.70

>>> There were no adjustment instructions in the Adjustable Transmission Modulator box, but I did notice that there'* a set-screw inside the vacuum fitting.. I presume that'* how you adjust it, but what is the exact procedure? Turning it in makes it firmer, or vice-versa..?

I also liked the idea to "acquire BURN2 from Moates, program your own shift points and TCC lock thresholds"
- Although I don't know what a BURN2 is (or who Moates is) nor have the slightest idea of how to program said shift points.. but I like the concept lol

Thanks again to all for all the great info

That screw you saw in the vacuum line connection is the adjustment. I recommend adjustments in half turn intervals. Just keep track of it, as you don't want to get lost. Once you get lost, it can be really hard to find where the original setting was. Somewhere between a half turn and a whole turn is where most like it (myself included).