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Hello members! I am new to the this forum but members on other car forums as well. I am at a bit of a loss. I have had my 1993 LS400 for about 8 months. I bought it in Indiana, where I am from, as a wholesale car from a dealer. I bought it with some minor issues but in overall amazing shape. The car is from Florida so there is no rust on the car, (absolutely amazing find for Indiana). The previous owners took very good care of it and I bought it with 125,000 miles. It now has 131,000. Not bad for a 25 year old car at the time. I had to do some tune-up items on the car including plugs and wires and various other small things. The only thing that I am still trying to sort out is an issue when I go WOT to merge on highways or have fun. I love in Texas now so I need to go much faster, much quicker than I am used to! The symptoms are odd and I am a trained Automotive Technician and still am stumped on the issue. From a dead stop, the car is pretty quick and the transmission hooks up. It seems to be once I am moving and passed 40-50mph when I push the gas pedal all the way down or all the way down plus the little detent, the transmission shifts down ,RPMs increase but very little speed increase is achieved. It's like the transmission goes into neutral when floored.
I first thought maybe the kickdown cable was loose or tight. I adjusted that to factory specs. I then thought maybe fluid was low and it seems to be right where it should be. I then drained dropped the pan, cleaned out the filter and put new fluid back in. Just came from a test drive and it still does it. When in there, I also took out the 2 shift solenoids and cleaned those out as I had a 4Runner in the past that had a solenoid code and that fixed it.
I cannot think of anything else to look for but I do not believe that any clutches or anything major is messed up because when driving normal or slow it shifts just fine up and down. Any suggestions or ideas would help!
First thing that comes to mind is the little A/T shift solenoid (There's two of them actually). It is located inside the A/T pan, near those magnets there. Nineteen 10mm bolts hold the pan in place at the bottom of your car.
When I bought my car, it would absolutely not shift at all - I had to do it manually between 1st, 2nd and D. But I bought it like that, so who knows what things look like while solenoids are failing.
Did you pull any codes? I can't remember for sure, but I think mine threw a code for the shift solenoid.
Another thing that comes to mind is the TPS (Throttle position sensor). That sensor is supposed to send a signal when you floor the gas pedal - and it seems that your problem happens mostly when you floor it.
Yet another possibility is the ECU - have you checked your caps in it yet? It is located in front of the front passenger seat. Gotta take out the glove box first, then all the screws that hold the trim below it. The ECU is screwed into the lower middle panel, about knee height. Not too hard to get out those screws, as long as you don't mind being on your knees and sticking your head into the footwell.
Now I am no expert, so I am only guessing.
Another interesting experience: many years ago I drove a Nissan Stanza. The car was well maintained, drove like a rocket, but after holding it at 60mph for a while, it would start hesitating, and then stutter a bit, like I am releasing the gas pedal, and finally it would start slowing down. You can imagine how ugly that could be in a middle of a highway, just as you are trying to pass someone...
Anyway, no mechanic could figure it out. Finally I took it to AAA and asked them for help. They couldn't figure it out either. Then the guy there told me to go to a mechanic near San Francisco (They've been there long and are famous for being really good with Japanese vehicles). I took the car to them, and within an hour they called me back to tell me they fixed it!
I picked it up, and lo and behold - the problem was gone. I called them because I had to know what the problem was- it was an ECU ground wire that some bozo who repaired the stereo (before I bought the car) made contact with, but it was only doing it intermittently... they corrected the ground wire problem, and engine worked fine after that.
First thing that comes to mind is the little A/T shift solenoid (There's two of them actually). It is located inside the A/T pan, near those magnets there. Nineteen 10mm bolts hold the pan in place at the bottom of your car.
When I bought my car, it would absolutely not shift at all - I had to do it manually between 1st, 2nd and D. But I bought it like that, so who knows what things look like while solenoids are failing.
Did you pull any codes? I can't remember for sure, but I think mine threw a code for the shift solenoid.
Another thing that comes to mind is the TPS (Throttle position sensor). That sensor is supposed to send a signal when you floor the gas pedal - and it seems that your problem happens mostly when you floor it.
Yet another possibility is the ECU - have you checked your caps in it yet? It is located in front of the front passenger seat. Gotta take out the glove box first, then all the screws that hold the trim below it. The ECU is screwed into the lower middle panel, about knee height. Not too hard to get out those screws, as long as you don't mind being on your knees and sticking your head into the footwell.
Now I am no expert, so I am only guessing.
Another interesting experience: many years ago I drove a Nissan Stanza. The car was well maintained, drove like a rocket, but after holding it at 60mph for a while, it would start hesitating, and then stutter a bit, like I am releasing the gas pedal, and finally it would start slowing down. You can imagine how ugly that could be in a middle of a highway, just as you are trying to pass someone...
Anyway, no mechanic could figure it out. Finally I took it to AAA and asked them for help. They couldn't figure it out either. Then the guy there told me to go to a mechanic near San Francisco (They've been there long and are famous for being really good with Japanese vehicles). I took the car to them, and within an hour they called me back to tell me they fixed it!
I picked it up, and lo and behold - the problem was gone. I called them because I had to know what the problem was- it was an ECU ground wire that some bozo who repaired the stereo (before I bought the car) made contact with, but it was only doing it intermittently... they corrected the ground wire problem, and engine worked fine after that.
I am going to look at the TPS. I have had an issue with it in the past and I have tried adjusting it and the RPMs never change and I did it the factory adjustment as well with inconsistant readings. I never thought of that causing the issue. I know it was replaced by the previous owner before but I'm thinking it may be bad.
I took the shift solenoids out and cleaned them but I have no codes so didn't expect those to be the issue.
If it were my car I'd try two things - going a little higher on the fluid level and/or a couple drain and fills with Castol transmission fluid.
I've done 2 drains and refills with Valvoline Maxlife. The fluid is pretty clean coming out and just some small gray matter in the pan when I took it off. I think it's something electrical. The TPS was mentioned and I've had problems with it before so I'm thinking that may be the issue. I'm to order a new one and see if that helps it.
I'm hoping someone else chimes in, ONLY USE TOYOTA T-IV FLUID IN THE TRANS. I'm sure Castrol and valvoline are quality fluids, at least for most cars, but this transmission was designed for the specific Toyota fluid. After doing a pan drop and clean on my 1997, I ran out of Toyota fluid and added a quart or so of Valvoline Maxlife (I use it for the power steering fluid in my LS and my girlfriends ES) and the transmission did not shift the same or hold the gears at high RPM and throttle like it used it. It was definitely noticeable, especially on cold starts and pitting it into gear, it just felt a little less connected. And yes, the transmission was at the proper fill level with the car fully warmed up and running. I have since done 2 or maybe drain and fills (its about 2.5 quarts per drain) and the shifts firmed up and bit and made a big difference. No hesitation putting it into gear (even on a record -60F this past winter). Grab a 6 quart case of T-IV off amazon or Ebay or even your local lexus dealer and put the good juice in. It's not expensive and rules out the possibility.
I'm hoping someone else chimes in, ONLY USE TOYOTA T-IV FLUID IN THE TRANS.
i'll chime in, yes only use transmission fluids that meet the JWS 3309 or GM 9986195 standard (type t-iv, mobil 3309, etc...)
and as you said it's not like it's crazy expensive either for the toyota fluid, if one needs to save $8 on a transmission service then owning this car might be beyond their means
Thank you Bradland! I want to make time to watch that entire video, and that man knows his stuff. Every single transmission is made differently; different oil passages, different clutch material, different everything. Lexus/toyota spent BILLIONS on the research and development of the ls400. they have been servicing these cars for 20 years. nobody who exclusively has their car serviced at lexus is having transmission failure, but there are plenty of stories of cars with questionable service history and dead transmissions. would anyone make the argument "you put in the oem fluid and your trans died, you shouldve put some ford mercon V fluid in because it says on the bottle its awesome for every import and domestic car"? thats a big nope
Thank you Bradland! I want to make time to watch that entire video, and that man knows his stuff. Every single transmission is made differently; different oil passages, different clutch material, different everything. Lexus/toyota spent BILLIONS on the research and development of the ls400. they have been servicing these cars for 20 years. nobody who exclusively has their car serviced at lexus is having transmission failure, but there are plenty of stories of cars with questionable service history and dead transmissions. would anyone make the argument "you put in the oem fluid and your trans died, you shouldve put some ford mercon V fluid in because it says on the bottle its awesome for every import and domestic car"? thats a big nope
Looks like my mechanic didn't use Toyota t4 stuff...maybe that's what's causing the whine or rather didnt get rid of it. He used NAL PureSyn Multi Vehicle LV. What would be best, to drop pan or suck it out and replace with t4?
So funny all the people that are LS transmission experts as far as fluid to use. You can use what you want. But if you want the transmission to outlast everything else on the car use the proper stuff. Only the Toyota T-IV like mentioned above.
The guy in the video is great. Though I thought that type T would have been for the 89 LS transmission not in 93???
As we see there was a TSB not to mix dexron, in a type T transmission. Valvoline maxlife is dexron (wow per video its not even dexron). People just don't understand the huge difference between the different Automatic transmission fluids and types, many hours and many $ are spent on test rigs to adjust the friction materials and the shift pressures and schedules to perform to the additives in the transmission fluid type to be used. Read all you want on some fluid manufactures charts for compatibility, they are going to say what ever, when your transmission breaks from their fluid they will deny it was their fluid, all they have to say is its an old and high mile car what do you expect.(And I learned something new on the video about the licensing, just wow, that guy knows his stuff) I wrote some of this post before watching the video. It was a good 40 minutes spent.
You have to question that Valvoline maxlife says its okay for Mercedes, and all sorts of other brands, sorry there is no one size fits all fluid for transmissions. And using it in your LS or your Mercedes is asking for trouble.
Looks like my mechanic didn't use Toyota t4 stuff...maybe that's what's causing the whine or rather didnt get rid of it. He used NAL PureSyn Multi Vehicle LV. What would be best, to drop pan or suck it out and replace with t4?
Only real way to ever get mixed up mess transmission fluid out of an automatic transmission is an overhaul and torque converter replacement.
Looks like my mechanic didn't use Toyota t4 stuff...maybe that's what's causing the whine or rather didnt get rid of it. He used NAL PureSyn Multi Vehicle LV. What would be best, to drop pan or suck it out and replace with t4?
neither, both of those will only get a fraction of the fluid out
05-31-19, 12:32 PM
New Member- Transmission "slipping" on WOT
