Transmission Shudder

[dougs 400]

I have a '95 LS400 with 96,000 miles. It has a shudder in the driveline at approximately 45-50 mph. It seems like it goes into overdrive, then out, then in. Over 60 mph it is perfectly smooth. Anyone have any idea what is going on? Thanks for your help.

[pishta]

I have a '95 LS400 with 96,000 miles. It has a shudder in the driveline at approximately 45-50 mph. It seems like it goes into overdrive, then out, then in. Over 60 mph it is perfectly smooth. Anyone have any idea what is going on? Thanks for your help.

Sounds like the lock up clutch in the torque converter. A flush and fill with type T 4 transmission fluid will help out loads. Probably needs a filter change while they are in there. Lexus doesn't fix these, they just install a rebuilt one from Lexus according to some posts. If you go independent on this job, insist that they use the type T 4 fluid, no Dextron or other fluid will do, bring it with you if in doubt.

[nc211]

Doug, crucial question: Is it doing it when you take your foot off the gas, like it's jerking a bit? Say you're just cruising at that 45-50mph window, nothing aggressive, then you take your foot of the gas to coast....is it jerking then?

[dougs 400]

Doug, crucial question: Is it doing it when you take your foot off the gas, like it's jerking a bit? Say you're just cruising at that 45-50mph window, nothing aggressive, then you take your foot of the gas to coast....is it jerking then?

It is just jerking when I let off of the throttle just a bit. If I am accelerating, even very slowly, there is nothing but smoothness.

[nc211]

it's you engine computer...you have what is known as "Off-Throttle-Shock", which is part of the largest technical Sevice bulletin ever issued on the car. I had this too on my 95 and forced the dealership to replace my computer under their 90 day window warranty. What is happening is that when you take your foot off the gas ever so slightly, the computer is cutting the fuel to the engine too quickly, which is creating a reverse-torque in the driveline, which is the buckeling/shutter you're feeling. Do a search for "Off Throttle Shock" and "ECM" you'll see some posts and attachments, one of which is the actual TSB issued for the fix. The computer is not cheap, but there are ways to have it reprogramed in the aftermarket world. I guarantee, it's your computer.

[dougs 400]

Thank you for your input nc211 and Pishta. It's really great when knowledgeable people will take their time to help other people who don't know as much. I now know that my Lexus dealership was probably !Removed! me around, and knew it. Just looked at my records, and I had it in to them three times for this problem (when it was still in warranty). They changed my fluid once, and said that would fix it. When it didn't, they conveniently said later that they couldn't reproduce the problem.

What is the prognosis of this malady? Does it get worse with lots of miles, or just stay the same. If it doesn't get worse, I am going to have to ignore it. If it does get worse, I will have tochange the ECM.

I have had the fluid changed recently, but no help. They said they changed the filter, but who knows. It was not at the dealership. I have no idea if they used T4 fluid or not. Is that of primary importance?

Once again, thank you for your answers.

[nc211]

Thank you for your input nc211 and Pishta. It's really great when knowledgeable people will take their time to help other people who don't know as much. I now know that my Lexus dealership was probably !Removed! me around, and knew it. Just looked at my records, and I had it in to them three times for this problem (when it was still in warranty). They changed my fluid once, and said that would fix it. When it didn't, they conveniently said later that they couldn't reproduce the problem.

What is the prognosis of this malady? Does it get worse with lots of miles, or just stay the same. If it doesn't get worse, I am going to have to ignore it. If it does get worse, I will have tochange the ECM.

I have had the fluid changed recently, but no help. They said they changed the filter, but who knows. It was not at the dealership. I have no idea if they used T4 fluid or not. Is that of primary importance?

Once again, thank you for your answers.

T4 fluid is very important if you ask me. I've only used it, never would diverge from it.

You say you had the car into the dealership 3 times for this same problem while it was under warranty? How long ago was that? I'm assuming it was years "original owner?". If not, if it was recent, then the clock is still ticking on the warranty, and you have legs to argue that they are dodging the problem to avoid having to pay the $2,300 for the computer, which is exactly what my dealership was doing when i bought mine back in 04'. Thankfully, I found this site, found that TSB, and marched right back in there and said "out of all of the TSB's ever issued on this car, this is the ONLY ONE that is HIGHLY recommended by LEXUS/TOYOTA to be performed. You didn't miss it, you just don't want to own up to it!" Guess what, they fixed it. I don't know what the long-term life of the ECM is, but I do know you can hammer down on them by pointing out the fact that this is the one problem that has been repeatedly reported to the NHTSB by numerous owners, the dealership failed 3 times to fix it, and you now have proof as to what SHOULD HAVE BEEN DONE the FIRST TIME!

I guarantee you, freakin' guarantee you, that if you were to go back to the dealership now, out of warranty with this problem, they'd go straight for that TSB and charge you the thousands of dollars to fix it. No doubt about it... On their dime? "we don't know what's wrong"...on your dime? "it's your engine computer, well known problem for the 95-96' series, $2,300 for part alone".

If your service was recent, and they're doing this cat n' mouse routine with you even after you present this finding to them, and the fact that they've never fixed the problem, and won't acknowlege the computer, then call Lexus Corporate in California and complain. Let the Corporate Office put the pressure on the dealership to perform it's responsiblities, as perscribed by Lexus. They'll do it then I bet!

[Sanpete]

Strongly agree with nc211 about the warranty issue. They should have fixed this under warranty, and are still bound to do so because of their misleading you about it when it was under warranty (whether it was an honest mistake or not--it's hard to see how they could have missed it, though). Don't let this go; it will decrease your car's performance and resale value.

[lihtemup]

Doug, crucial question: Is it doing it when you take your foot off the gas, like it's jerking a bit? Say you're just cruising at that 45-50mph window, nothing aggressive, then you take your foot of the gas to coast....is it jerking then?

I have a 98 LS400, seems very similar...when I take my foot off the gas the rumble/shudder continues. Usually if I give it more gas it shifts and is smooth...been told I need to put an additive for shudder in but I'm nervous...150,000 mls. Any advice would be greatly appreciated!!! Nick

[nc211]

The computer issues were resolved in late 96 - early 97 models, so you're clear of that monster!

Who told you to add an additive? The dealership, or someone else? I would not introduce anything of the sort into your transmission!!!!! When was the last time you had your transmission fluid replaced? Was it with genuine Type 4 Toyota fluid? How about your transmission mount?

[dcfish]

100% Agree with the use of Toyota T-4 Fluid only, Never add anything to your tranny except T-4 fluid, You would be asking for problems....................

[lihtemup]

The computer issues were resolved in late 96 - early 97 models, so you're clear of that monster!

Who told you to add an additive? The dealership, or someone else? I would not introduce anything of the sort into your transmission!!!!! When was the last time you had your transmission fluid replaced? Was it with genuine Type 4 Toyota fluid? How about your transmission mount?

Mom and Pop shop recommended the additive, I didn't like the sound of it so I came here....Lucas is what most people say, but I'm still hesitant to put anything but tranny fluid in it...at around 110,000 mls I did the maintance at the dealership that includes fluid flush, new timing belt etc. the dealership said everything about the transmission checked out great. It seems my problem was improved with the new fluid (and I assume the Lexus delearship used correct fluid) but not eliminated. Over time it continue to get worse, but very very slowly....With my last oil change I decided to do the drain 2 qts and add new. My fluid was very dark almost purple in color. I plan to flush two more qts soon....

It assumed it would be more than a fluid issue just because it is as bad today (if not a little worse) as it was 2 yrs/40,000 mls ago before Lexus gave me new fluids and I thought tranny fluid lasted longer than that, or is thi sjust a bad assumption?

It's good to know I'm clear of the computer issue. Thanks!!! Here's my plan, I'll check my paperwork and call dealership to see if transmission mounts were inspected. If no, I'll look into that, not sure how difficult that is.... I read a post where it was recommended to turn OD off to see if the issue on the highway persist. I'll try that too.

I've heard replacing too much transmission fluid at once can shock a transmission...is that true with Lexus as well? If I want to do the routine where you drain two qts at a time, how often should I do it at the most? Every 500 miles too often? Or every 5000 mls?

Thanks again, will keep you posted!!! I love my 98 and don't have the cash on hand for a tranny so I want to do everything I can now to get 100,000 mls more out of it...I'm sure you understand!

[nc211]

Chances are, you're due for a new tranny mount. I'm guessing it's probably the original. The two motor mounts are probably due too. It's not so much the mileage on a mount, but the time. My 01 GS has only 58k miles, but the mounts are compressed to the point of needing replacement. The tranny mount is very easy to do. If you're doing your own fluid changes, you can easily do the mount yourself. www.parts.com is a good spot to buy one, they're called the "rear mount". You only need one. You need two "front mounts" if you want to replace the motor mounts. That's not a diy job for most "me included".

Doing the 2 quarter out/in routine is a good thing, and you can't "shock" the system that way. The only way you can shock it, is if you use a highpressure flusher at a point in time where the old fluid is just so bad, the pressure of the machine forces all the gunk through the system too forcefully. Do the drain n' fill at each oil change (5,000k on full synthetic) until you see the old fluid starting to look like new "red". Then, I'd do it every other change.

At your car's age...the mounts are probably pretty well compressed, which will create some vibrations and funky "slack" feels in the operations of the car.

I'd swing by your local TOYOTA dealerhship and buy a case of Type IV fluid ($50-$60 bucks). Use that until it's gone (should last you a good long time). Don't use anything but oem fluid (or amsoil compliant fluid - lots of guys on here like that stuff too). I wouldn't buy the fluid from the Lexus dealer, unless you want the added retail markup. It's all the same stuff!

[lihtemup]

100% Agree with the use of Toyota T-4 Fluid only, Never add anything to your tranny except T-4 fluid, You would be asking for problems....................

I've seen a Castrol Import Transmission fluid at parts stores, it says it can be used on Lexus in place of type IV. Any opinions on the Castrol brand fluid? I'm using it for my power steering today....

[nc211]

It might work, but oem will work. It's ok in the power steering system, but do you want to risk it in your transmission? Is the cost savings really worth the possibility of transmission problems?