1990 Lexus Ls 4oo Slows Down By Itself

[Mike Hoop]

My 1990 Lexus LS 400 seems to slow down on its own when I am going faster than 50 mph. I would say that the torque converter is stuck in lockup, but it glides around real nice at lower speeds, everything else seems to work right, and it shifts rather well. Maybe this is normal, but this is my first lexus, and I want to be sure that it is performing properly. Anyone else experiencing this same problem, or is it in my head...

[chilkoot]

sounds like your o/d isn't engaging, make sure it's not turned off.

[Mike Hoop]

sounds like your o/d isn't engaging, make sure it's not turned off.

I thought that too, but the trans shifts 3 times into all 4 gears, but it drags a little in fourth gear, my old chevy used to do that, so i replaced the torque converter and problem solved, i just wondered if that kind of thing was just the way toyota designed it.. I find it helpfull at sometimes when I want to slow down a little on the highway i just let off the gas, but it makes for a ruff ride, I mean for a luxurey car... I did a diagnostic on the trans and i'm not experiencing any electical problems with the trans, Is there anyone out there that drives a 1990 lexus ls 400 that can confirm that thier car almost mantains speed on its own when traveling on the highway, or does it tend to "naturaly slow down" when the gas is released at high speeds

[RFeldes]

If I'm not mistaken, O/D is your fifth gear, Like chilkoot said. The button on the shifter is O/D. You said four gears.

[Mike Hoop]

If I'm not mistaken, O/D is your fifth gear, Like chilkoot said. The button on the shifter is O/D. You said four gears.

It'a a four speed automatic, and i'm not a fool the overdrive is on. duh

[Mike Hoop]

If I'm not mistaken, O/D is your fifth gear, Like chilkoot said. The button on the shifter is O/D. You said four gears.

It'a a four speed automatic, and i'm not a fool the overdrive is on. duh

If i turn the overdrive off i it downshifts even at higher speeds, so no its not the overdrive ok. Any one driving a lexus ls 400 that experiences a slight drag if its not the overdrive brakes ect.. I just wondered if it was normal, the other car I drive seems to coast a little better...

[Vern Dias]

If I'm not mistaken, O/D is your fifth gear, Like chilkoot said. The button on the shifter is O/D. You said four gears.

It'a a four speed automatic, and i'm not a fool the overdrive is on. duh

If i turn the overdrive off i it downshifts even at higher speeds, so no its not the overdrive ok. Any one driving a lexus ls 400 that experiences a slight drag if its not the overdrive brakes ect.. I just wondered if it was normal, the other car I drive seems to coast a little better...

Low tire pressure, possibly?

Vern

[steve2006]

The autobox on the LS will not change up to top gear until the transmission fluid is up to normal temperature and I notice mine drags on over run when cold as it is still in 3rd.

[chilkoot]

I've never noticed any engine braking in either of the LSs I've driven, through good or bad mechanical condition.

There was recently a thread posted about how flushing the PS fluid helps mileage by reducing drag on the engine, how are the conditions of your fluid? How old are your idlers/tensioners? If it's slowing down by itself in O/D it sounds like there's undue drag on the rotating assembly somewhere.

[RFeldes]

If I'm not mistaken, O/D is your fifth gear, Like chilkoot said. The button on the shifter is O/D. You said four gears.

It'a a four speed automatic, and i'm not a fool the overdrive is on. duh

First off, if you seek help on this forum (duh) is not something to say that garners a lot of heartfelt help. I admit, I may have been wrong as I now have an 02. Getting older and really can't recall if I had a fourth to O/D drive on my 90. I do own my 02 and do apologize if I am wrong. I was trying to help, as most of us do. Good luck in solving your problem and I mean it sincerely.

[Mike Hoop]

Thanx for your help guys, I will try the power steering fluid idea, as for the autobox Idea, the engine reaches normal temp, what sensor, or device would fail that would cause the trans fluid to run at a colder temp, or are you saying I should change out the fluid... And for Rfeldes, I am sorry I did not mean to offend I was just trying to eliminate the obvious, sorry....