1998 Ls400 Shifting Issue

[hopmuzk]

Hi everyone. I purchased a 1998 LS400 a few months ago and have noticed when leaving my neighborhood, when I turn out onto one of the

streets with a dowmhill slope, at maybe 5mph the RPM's reach around 1800 and it seems the transmission is trying to play catch up. It's as if the

transmission changes to a much lower gear ratio or something.The transmission doesn't seem to change real hard or anything. I recently removed the transmission pan and replaced the gasket and fluid. I would have changed the screen but due to a certain auto parts store I was given the wrong screen and would have to wait for three days before the correct one came in so I cleaned the screen best I could and reused it. I did notice one of the magnets was missing and another was magnetized to the tranny. I placed them back where they belong in the pan. T-IV fluid is what I used. Noticed a few brass looking particles and greyish sludge on magnets. The same symptoms are still there. I've done a lot of reading and can't find anyone with a problem exactly like what I've been having. Is it possibly the throttle cable? Solenoid? No dash lights are on indicating a problem. The car seems to shift fine through all the gears going down the highway it just seems like the problem is only there when I slow down and turn into another street and start to accelerate again. This happens after car is warmed up. Any help would be so greatly appreciated guys. Thanks in advance. Tim.

[1990LS400]

It is normal on the 1998-2000 LS400 when the transmission is cold. Mine does the same thing.

[hopmuzk]

Thanks for the reply 1990 LS400. The thing is I'm pretty sure it does it after warm up. Seems like it doesn't do it as much on level ground as when I'm driving down a slight incline.

[1990LS400]

The car seems to shift fine through all the gears going down the highway it just seems like the problem is only there when I slow down and turn into another street and start to accelerate again. This happens after car is warmed up.

This may just be the nature of the beast. A number of people have complained about the transmission getting a little confused in a situation like slowing down, turning a corner and then accellerating. IMO, part of it is due to the engine's torque characteristic and transmission shift program which "remembers" the previous few shift cycles. I believe that most of it, however, is due to drivers not pushing the accellerator down and actually momentarily backing off the throttle before they apply it, confusing the transmission ECU and then lurching forward. I do this too occasionally. My suggestion is to drive a couple of similar 98-00 LS400's cars in similar situations. How many miles on your 98?

[hopmuzk]

Just turned 177,000 miles. I'm assuming you have a 1990? How many miles on it?

[1990LS400]

Just turned 177,000 miles. I'm assuming you have a 1990? How many miles on it?

I sold my 1990 LS400 in 2003 after driving it from new until 183,500 miles. I bought an off-lease 2000 LS400 earlier in 2003 at 38,000 miles and have driven it to about 152,000 miles. It is is remarkable condition.

The 1998-2000 5-speed transmission and the similar 2001-2003 LS430 5-speed transmission may be the most reliable and trouble free transmissions Toyota has ever made.

Does your 98 LS have a full maintenance history? Has it had occasional transmission fluid changes?

[billydpowell]

Just a friendly note: ALL auto tranny's are designed to operate under "pressure", or torque, if you will.. and they have no real brains.. so if they go from 0 to 149 you have a good one, and dont worry about what they do when they are "floating".

just enjoy them.

[hopmuzk]

Just a friendly note: ALL auto tranny's are designed to operate under "pressure", or torque, if you will.. and they have no real brains.. so if they go from 0 to 149 you have a good one, and dont worry about what they do when they are "floating".

just enjoy them.

Thanks Billy.

[hopmuzk]

Just turned 177,000 miles. I'm assuming you have a 1990? How many miles on it?

I sold my 1990 LS400 in 2003 after driving it from new until 183,500 miles. I bought an off-lease 2000 LS400 earlier in 2003 at 38,000 miles and have driven it to about 152,000 miles. It is is remarkable condition.

The 1998-2000 5-speed transmission and the similar 2001-2003 LS430 5-speed transmission may be the most reliable and trouble free transmissions Toyota has ever made.

Does your 98 LS have a full maintenance history? Has it had occasional transmission fluid changes?

It has a decent history. A few transmission fluid changes but this one I did was overdue judging by the look and smell of the fluid. I'll bet that 2000 LS400 is a beaut.

[1990LS400]

A few transmission fluid changes but this one I did was overdue judging by the look and smell of the fluid. I'll bet that 2000 LS400 is a beaut.

These transmissions don't really require much maintenance. I have the fluid in mine changed every 30,000 miles and I know that is overkill.

Photos of both my previous and current LS400's are in my gallery: http://us.lexusowner...157&tab=gallery The 2000 is very nice and I was surprised that I found it more pleasant to drive than the 2012 LS460L AWD I test drove last fall. It's going to be hard to part with it but, as it's value falls, its becoming a fender bender away from being totaled out.

[Yamae]

This may just be the nature of the beast. A number of people have complained about the transmission getting a little confused in a situation like slowing down, turning a corner and then accellerating.

This is about my 98 Celsior (JDM) and I used to have exactly the same problem mentioned above. Some people here were claiming that it was a nature of 98-00 Celsior but Others were denying it saying ours are not like that.

I happened to clean the throttle body aiming to improve the low idle rpm. It was sometimes below 300rpm or less at D. After the cleaning, the idle went up to 550rpm. Also the hesitation problem has gone away. I mean the poor acceleration after turning the corner then the sudden acceleration was not there any more. What a big difference, I noticed.

I am new here and this is my 1st post. I am a Japanese electronics engineer who used to work at San Diego CA before. I am still not good at writing English but I have some good experience to fix cars especially electronics related areas such as ECUs, motor controllers and sensors. I will be posting more in the near future.

[TREKKIEJAZ]

Hi,

Did you ever figure out what was causing your low speed shift problem? Mine does pretty much the same thing as what you described. If I accelerate, slow down and then accelerate again like in stop and go traffic, sometimes the engine rpm's will go way up and then it jumps into 1st gear again. Almost as if it went into neutral for a few sec's and then back into gear. Like the engine is having to catch back up with the transmisstion. It's pretty odd I think. I don't really remember it doing that until the last fluid change was done. Toyota IV fluid was used. I also notice a slight rpm flare say around 100 rpm or so between 1st and 2nd. I don't remember it doing that either. It actually shifts too smooth for my liking. I like to at least feel something between gears.

Thanks,

Jason