Bill Dowd

I it's a good idea to change your trans fluid every 25,000 miles I also put in a transmission cooler and I pump 4 quarts of fluid every 20-25,000 miles and drop the pan at 60,000 miles. I've switched to mobil one synthetic fluid so far no problems at 236,000 miles my lasl trans went 529,0000 miles plus in a toyota cressida due to cost I recommend using type 4 toyota trans fluid the same as lexus fluid . CHANGING THE FLUID IS SO IMPORTANT ALSO DON'T FORGET TO CHANGE THE POWER STEERING FLUID AGAIN I USE MOBILE ONE and don't forget the rearend oil different years use different kinds due to limited slip.

PureDrifter

iTrader: (10)

LS400's never came with LSDs.....ever.

amcdonal86

Not so good for drifting, is it?

smokincigs

I flushed mine 35,000 miles ago and have had no problems. It seems to be much smoother.

dantampa

Thanks for all of the suggestions. This forum is wonderful. I made an appointment with Lexus for this weekend in order to have them inspect my transmission fluid. Once they've inspected the fluid, I'll likely have them replace it. I'm also having them change my rear differential fluid.

Based on the responses to the first part of my post, I now feel pretty comfortable about the fact that the car stays in 2nd gear for a while when it's cold out.

My second question, however, really didn't get addressed.

The other issue my transmission seems to be having is an over-eagerness to shift into low gears when slowing down. For example, if I'm going 40 mph down a road and then slow down to 5-10 mph in order to turn onto a side street, the car almost always ends up in a gear that is too low which causes the car to lurch forward as soon as I give it gas after making the turn. I know this can't be how the car was intended to act because frankly it's quite awkward feeling.

Can someone please help shed some light on this?

Thanks as always,
Dan

michaelwu5

dantampa,

Regarding your second problem, does it make any difference with AC on or off?

I have a 1998 LS400 with 113k miles on it. When the AC is on, car acceleration from slow speed feels awkward, the engine RPM needs to go higher compared to when AC is off.

dantampa

Nope, the AC being on or off does not change the slightly odd symptoms of my transmission. Good luck with yours though!

By the way, per the advice of some of the people who responded to this thread, I recently took my car to the local Lexus dealership and had them replace my transmission fluid (they told me they do it twice, back to back, in order to sort of "flush" the transmission.) Regardless, there was zero change in my car's shifting pattern.

I've been thinking... Maybe the people who owned this car before me drove with a really "light foot" (i.e. very slow to accelerate) whereas I am sort of a lead foot (I've already seen 140+ MPH in this car several times lol). Maybe this could be fixed by disconnecting the battery and allowing the transmission to "relearn" the driving habits of this new owner? It's almost as if the transmission is incorrectly "guessing" what my next move will be and that is why I find the transmission in the wrong gear from time to time. Who knows... Any thoughts?

michaelwu5

Hi, dantampa,

Have you got the problem fixed? I also have experienced the same symptoms that you have described and I think I have it fixed.

I also thought it was transmission related problem and I had the transmission oil and filter changed but did not help. My shift solenoid A on the transmission also malfunctions and got changed and did not help either.

What I did was de-carb the engine with 3M Foaming Engine Conditioner. My engine does pinging and knocking before the cleaning at around 1200RPM in 5th gear. I had a lot of carbon deposits on the piston head and I had to do the de-carb procedural several times. Because 3M Foaming Engine Conditioner only works wile the engine is hot, so I actually had to: run hot -> take off spark plugs -> clean -> put spark plugs back -> run hot -> take off spark plugs -> clean -> put spark plugs back.

My theory is this: When the car de-accelerates then give it more gas, it will want to use gear 3 with very high torque. This puts a lot of burden on the engine and is when pinging and knocking will happen. The ECU then decides that it has change to gear 4, this is where the sudden kick coming from.

I think my engine condition is very close to getting knocking on gear 3 under hard acceleration, so when I turn the AC on (putting more burden on the engine) things become much worse.

Hope this helps and good luck!

CalixCris

A.Drain Transmission fluid fill 3 parts transmission fluid & 3 parts Lucas Transmission Slip ... B. Test Transmission Sensors .. C. New Transmission

PureDrifter

iTrader: (10)

now why would you add an additive to a car that's extremely sensitive to fluid....

dantampa

michaelwu5,

Thanks for your interest in my transmission problem and for taking the time to let me know about your experience in order to try and help me. These forums are wonderful like that.

Unfortunately my car does still have weird shift behavior during lower speeds (< 20 MPH?). I am not really familiar enough with engines to know about the type of knocking and pinging that you've described.

However, here is something that is interesting. Even when I first bought the car, I noticed that it has quite a shake at about 2,000 RPM. When I was first testing the car before buying it, I decided to leave the car in park and slowly "sweep" through the engine RPMs up to about 3 or 4k RPM (don't ask me why I thought this was a "good test" LOL -- I'm kinda car stupid). Anyway, at about 2,000 RPM the entire car shakes! After owning the car for a while I brought it to the local Lexus dealership and they attributed this to me needing to "eventually" get new motor and transmission mounts as they said they are pretty much "shot". Could that contribute to what I'm experiencing with the weird shifts?

And recently, I started noticing some pretty intense sort of "reverberation" effect while driving along at about 60 MPH. The car is running fine and the engine RPMs aren't jumping or anything weird like that but the whole car is sorta like "wah wah wah wah". I can almost feel it like the cabin pressure is fluctuating or something. Honestly I know something weird is taking place but I'm at an almost total failure to try and describe this in words. Okay so this is really hard to describe LOL but try to bear with me.

Thanks,
Dan

L2KeepUp

Hey Dan, I know this is a REALLY old post but I was wondering if you ever found out what the reverberation was around 60 MPH? Mine is a 98 and around 45-50 mph if I leave my foot in place at a constant speed it does that reverberation. It only does it in the 45-50mph range. Its kind of annoying honostly lol. I checked the wheel balance and all of my tie rods and stearing is new so I know its not that. It has to be a tranny issue but I can't find a thread that states what it is.

Also, my transmission doesn't do the hight rev thing too often but when I back out of my driveway after the car has been sitting over night it will sometimes slip out of reverse and stop powering the transmission. All I do to fix it is put it in neutral real quick then back into reverse and it works again. It has 213k miles on it so I expect some tranny issue eventually, just wanted to know if anybody knows if it's serious.

Thanks for any help,
Ben

dantampa

Hi there Ben,

I had the local Lexus dealership replace the motor and transmission mounts on my car and the reverberation instantly disappeared. The car rides smooth as glass now. I had the motor mounts and transmission mounts replaced at the same time so I can't tell you if it was only one or the other or both that actually needed replacing.

Hope this helps!



--Dan

L2KeepUp

Thanks for the reply, I didn't expect any help due to the age of this post lol. I replaced the motor and tranny mounts when I got the car. It fixed a lot of the vibration but I still get a slight reverberation at around 45-50 mph. I did a lot if digging on the net and the only thing I found was that it might be in the rear differential. I'm going to replace the fluids and hope that helps but I'm betting its a bigger issue in the dif. Either way I'm just going to run it until it becomes a real problem. It doesn't effect the drive at all if I avoid 45 mph lol.

Thanks again!

Lavrishevo

iTrader: (1)

Might want to check the bushes at the differential. Good to change the fluid but your vibration is most likely related to worn bushes.