95 Ls400 Transmission Issues

[NWFLS400]

I searched a bit and was not able to find this issues discussed so far.

This is a bit difficult to explain, but what I think it is doing is when you let off the accelerator, it immediatley downshifts, rather than letting the transmission coast in the higher gear. Not sure that is what it is really doing, but it feels like it is falling on it's face for a split second or hesitating, but it is coming from the tranny and not the engine.

It is worse if the ECT button is set to normal, but does it either way. It also seems to it mainly when you go to give it gas, but then light turns or something and you let back off all in the same 2 seconds or if you let off too quickly.

Not real consistent, but enough that I want to eliviate the issue.

I do not have a lot of history on the car, it had 125k when I bought it last spring, I now have about 148k on it, I have had the tranny fluid changed by a regoinal high class tranny place, but not a dealer. I did not want to do a flush, since I was not aware of the last change and I know that it may cause more of an issue, lets say of the last owner had never changed it in the 1st 125k.

I did notice that someone had posted that the tranny's like Toyota fluid, how different is it really from a high grade aftermarket? Maybe it is, just wanted to get some more opinions.

A person I did have test drive it for me thought that either the EMC for the tranny (which I think is shared with the engine?) may need to be replaced or maybe needs a flash update to the firmware.

Any help or advice would be appreciated.

Charles

[Kennyr]

Getting a fluid change without a flush is worthless. 2 qts. maybe a little more came out. Have a complete flush with or with out a flush machine and use only Toyota fluid or a universal synthetic fluid for your transmission. I hope the high end shop didn't charge you more than 30 bucks for the 2 quarts they changed. Waist of time and money. That's like changing your baby's diaper and not cleaning his butt. If you start with a new or clean trans and change the 2 quarts often enough I guess it will be better than nothing. I'm not in the camp that says flushing an older trans will hurt it. I think that is an old fairy tale that someone started and enough people will believe anything. Just my opinion.

[nc211]

This sounds like a variation of the "Off-Throttle Shock" syndrom produced by the engines computer. You'll see below in my signature that I replaced my ECU unit. Let me ask you this...what are the conditions for this? What speed range, uphill, downhill, flat? That sort of thing.

edit: I just saw your other posting about your check engine light. My problem I described above won't trip the engine light. I'd follow the engine light problem first before considering my suggestion.

[99lsguy]

I would only put Toyota T-IV tranny fluid in the car....

You can buy it by the case at Toyota dealer for under $4 a quart. They will also do the tranny flush for you if you wish - cheaper than the Lexus dealer.

[91ls400]

My toyota dealer I work with doesnt have the T-IV fluid by the quart, but they said they could sell it by the gallon if i brought them a container in. Im going to take this as a good thing and demand a better price, what do you think I should offer to pay for a bulk gallon of trans fluid?

[gennadiy008@yahoo.ca]

I just got the same problem whith my LS, 1995 , when you go to give it gas and then you let off the accelerator it does BOOM , sounds like it upshifts and right away downshifts, just funny trany behaviour. Also can hear that freaking Boom when u going to stop at the lights just before complete stop.

I thought that trany flush will help, so just got it done whith Toyota T-IV, - but it didnt. :cries:

Any ideas?

[NWFLS400]

Kennyr - I appreaciate your opinion and wander myself, although I had an issue with an old nova that I bought, ran a bunch of marval's mistry oil to clean it up and ended up with a knocking noise (many moons ago as a teenager) Never the less the idea was to change the fluid and filter every 5 or 10 thousand miles several times, then do a flush, but may be a waste of time. But will insure that I have Toyota flush it this time. I usually do most of my own work, but have always had pickups usually and can not get used to working on the bottom side of this thing, next garage will get a pit to work in... :D

nc211 - Thanks for the reply. The syptom is similar to what gennadiy008@yahoo.ca stated in a reply, but mine really does not make any noise when it does it. The situation is difficult, as right now it does not do it very often, yet most of my driving is hwy - I drive about 140 miles round trip to work :o gas prices - :cries: Either way it does not seem to matter what the speed is or what the grade of the road is. As long as you are moving forward with power or you are accelerating or complete declerating without your foot on the pedal it never does it. It only happens in the transition between adding power and taking it away. Which is why it seems to happen when I think I am going to accelerate, but the light changes or someone hits there brakes, so I go from adding power to accelerate to quickly taking it back off to apply brake. Hope this helps explain it better, but either way I am going to have it flushed by Toyota and take it to a guy I know that has a scanner and go from there. I don't think the trouble for the engine light has anything to do with (as I have driven it 20k miles and the issue with the tranny has been there since I bought it and the engine light is a recent issue) also the flush will probably not do anything but it needs it anyway, plus I do not want to have a compounded issue.

gennadiy008@yahoo.ca - The only thing I have noticed when coming to a stop sign is that if the A/C is on, sometimes the idle kicks up just as it is going into 1st gear, so as you apply even brake pressure it feels like it wants to take off again. Nothing major, but it is noticable.

Any further information or sharing of experiences would be great. Thanks