I need some advice please. I bought a 1992 LS400 about a year ago. I had 58,000 miles on it (now 64,000). About a month ago it started "chugging." It's OK when cold... for the first 3 or 4 miles. After that it "chugs." It does this only when I'm trying to maintain a steady cruising speed (happens at all speeds... 30, 40, 50, 60 mph). It goes away if I accelerate or if I take my foot off the gas pedal. Sometimes goes away after the car gets good and warm. It shifts fine (goes into gear right away, no slipping, no hesitation, no tranny noise). My mechanic said it's the transmission acting up so he changed the transmission fluid (removed the pan and replaced the filter) then refilled with Toyota T-IV. Then he ran it, drained it with the plug on the pan and refilled again. I've driven it almost 60 miles since he did that and notice no difference.... at least not yet. I bought enough new T-IV to run it then drain 2 Qts by the plug three more times. Will it begin to clean itself with the new fluid? I don't want a trans flush. He said it was the original pan seal from the factory. He checked the engine and said it's OK. He had installed a new timing belt and new plugs 12 months ago. I use Seafoam periodically in the gas. So what's going on??? Jeff "byerjv@yahoo.com"

Does it seem to be doing it when its in overdrive, like when the lock-up converter is engaged?

Does the car ever stall out? This description may be somewhat helpful:

http://ezinearticles.com/?Torque-Converter...p&id=113485

Chugging... Did you happen to get the LS400 "Choo-Choo" edition?

By chugging, do you mean "surging"? Transmission "hunting"? Is the engine RPM fluctuating?
I am having a hard time visualizing this "chugging".

Thank you for your interest. I spent about three hours searching this site and found a couple other posts with this same problem, but I can't see where anyone has solved it. One post said "it only happens within the first 1/4 inch or so of pedal travel." Same with mine.... It's most noticeable after I feel the transmission shift at about 45mph. But, if I use the button on the shifter to take it out of overdrive, It still does the same thing, only at higher rpm, of course. I came to a stop light yesterday, then when I took it back up to 50mph, the symptoms had disappeared... only to reappear about 10 miles later. My mechanic thinks it's the lock-up converter sticking, but I'm still not convinced. Could it be the injectors are clogged or the the throttle valve needs cleaning? I drained another 2 quarts and refilled with T-IV after my drive yesterday and took the tape off the wires in the trunk. They all look real good, but I left them hanging there anyway until I get this resolved. Does a lock-up converter engage when in 3rd gear? I also disconnected the battery yesterday for about 15 minutes and reconnected to see if that changes the symptom - if only temporarily - as I thought it might be a computer problem. I've yet to drive it since I did the three things just mentioned. byerjv@yahoo.com

My mechanic used that word to describe it. I guess you could say it "jerks" kinda like it's "hunting" for overdrive. The RPM stays rock steady. It keeps doing it if I take it out of overdrive using the button on the shifter.

No, it never stalls.

That was some good info in that Torque-Converter-Lockup article. But, I don't seem to have any of the three symptoms described there (although possibly it's engaging in gears that it shouldn't be engaging in... I can't tell for sure.) It says the TCC is made to engage in high gear. I assume it could happen in 3rd or 4th gear since I have the button to take it out of overdrive. Third could be considered the high gear. Should I try to disconnect the TCC and see if the symptom disappears - as only a test... the article says "Most lockup converters are controlled by a wire or wires that plug into the transmission. It is possible on some models to simply disconnect this plug. This is not a problem and will only cause you to lose a little gas mileage. The RPM's will run slightly higher than before but will not harm anything or be an issue."

That might be a good place to start.

hove you checked for any trans. codes? My 93 ls does this now and then I have a trans code ( read off of the O/D light ) showing a code for one of the vehicle speed sensors.

I'm not sure if my mechanic checked for transmission codes. I'll ask... he said to bring it back if the drain and refill didn't help and he'll investigate further. Does the equipment to check transmission codes hook up at the same place as the engine diagnostic equipment? Do you check the transmission with the O/D on or off? Does yours jerk mainly at 45 to 55? Mine used to be OK after it warmed up... not so anymore... it seems like it does it every time I drive it. Not so noticeable on a rough road or when driving slow in town. But, I want it fixed. Jeff

Mine seems to be in that MPH range. I do not have a constant chug just one or two every now and then.

To check:

Use either DLC

turn ignition switch on, do not start

push O/D button on

use wire to jump E1 and TE1 on the DLC

read the O/D light flashes


I have cel code 42 for No 1 vehicle speed sensor

Thanks so much! That's a big help. I'm sure my mechanic will be able to use it. I'm not much of a mechanic. What does DLC stand for? Thanks again! I'll be sure to let you know (post on this site) how things turn out, but it might take a couple weeks.

The DLC is the diagnostic connector. one on top of the engine drivers side. And one under the drivers side dash.

I asked because sometimes when mine is in overdrive around those speeds and I quickly release the accelerator and press it quick again, it will kinda jerk a couple of times, but I was assuming it was from my completely worn out engine mounts and transmission mount allowing slack to cause that.

Otherwise my transmission shifts flawlessly and smoothly through all gears.

Do you know where the speed sensor is located? Outside the transmission?

Not sure, but on my old 1991 Honda Accord it was on the outside of the transmission and was very easy to change.

I hope your mechanic is knowledgable in imports. a diagnostic check is always the first thing to be done (on most cars with OBD1 or OBD2) - and most likely it is a faulty sensor causing your woes(hopefully an easily replaceable one). These trannys are almost bulletproof and yours with such low mileage im pretty positive the Fluid and filter was fine. Glad you replaced it with the recommended type though. please post the results of your findings!

Good Luck!

This is a long thread. Speed sensor maybe. To me sounds more like "Off-Throttle-Shock". NC described it as "It's reverse torque through the driveshaft". Lexus has a TSB for it. Looks not a cheap fix, but apparently works:

I had seen that thread, but mine is a 1992. Also, someone said that if you take your foot off the gas with "Off-Throttle-Shock" then it would jerk... Here's part of the thread.... "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?................ Response: 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……...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."

So, I'm thinking it's the lock-up on the torque converter. I think it's probably meant to lock-up in both 3rd gear and in overdrive. That's when it jerks. I haven't been able to make it jerk if I drive with the shifter in 2nd gear and keep it around 1500 to 2000rmp, just like when driving about 50 mph in overdrive. I'm going to see if it can be disconnected. Does anyone know if the lock-up feature can be unplugged/disconnected on a 1992 LS400? Temporarily - as a test. Thank you!

does the car jerk when you shift to drive or reverse. if so then you might need to adjust your throttle cable. common problem on LS'. also you can check the engine and trans codes if you go to lexls.com. very simple you can use a paper clip or small wire.

It never jerks when I shift into drive or reverse. It only jerks when trying to maintain a steady speed on level ground in both 3rd gear and in overdrive (most noticeable at 45 to 55 when in overdrive).... never in 2nd. It's a continual jerking every 1/2 a second or so. It feels like the engine is stumbling, but I'm almost sure now that it's the transmission. I'll take a look at the codes.

I used a wire to check for engine and transmission codes after work today. All I saw was rapidly and consistently flashing Check Engine and O/D Lights. OK - no problems stored in the computer. So, I decided to clean the throttle body. I sprayed it until it was spotless then oiled the shafts of the throttle blade inside the throttle body. A 20 mile drive and no jerking whatsoever. I think it might be too good to be true. But I came across a 19 page explanation of the TOYOTA ELECTRONIC CONTROL TRANSMISSION today. Wow, it explains everything about shifting, lock-up, etc. It also said "says “The throttle position sensor (connected to the throttle body) gives the Electronic Control Unit an indication of engine load to control shifting and lock-up timing.” Hmmmmm??? It says that Toyota's lock-up works in all gears except first... If the shifter is in "D" position. It also talkes about the water temp sensor which prevents shifting into O/D or lock-up until the coolant reaches a predetermined temp. If anyone wants a copy, I'll scan it. email me at byerjv@yahoo.com.

This is fantastic news! I hope the problem doesn't come back.

Please keep us posted if it does!

My 94LS has the same "jerky" problem at around 45 mph. It's not getting better or worse, it just is always there. Seems like a tranny thing. But since the A/C went out at the end of the Summer (and I live in Vegas, whew), and that now there is a slight rat-a-tat sound when just starting to accelerate and then when stopping, I think the LS is ready for dismissal. I'm going to drive it to its end, and then buy a Kia, or a Honda, or a Fisker Karma (I wish). Sad, a beautiful car, bought it with 97,000 miles, only 119,000 miles now, but there comes a time when you must say goodbye to an old friend. Best highway cruiser ever....

Maybe it just needs an oil change and a tune up! Don't give up so fast! 120k miles is pretty low mileage for these cars.

Another 30 miles today on a smooth, level road running at 55 to 60mph... no jerking. It used to start jerking at 45mph... I think it was the lock-up feature trying to engage. Now at 45 I can't feel anything, but can watch the rpm drop. I attribute it to cleaning the throttle body. WELL, I SPOKE TOO SOON. THE COLD WEATHER RETURNED AND THE CAR IS JERKING AGAIN AT AROUND 40 - 55 MPH. I READ THAT SOMEONE ELSE HAD THIS PROBLEM AND FINALLY AFTER A FEW YEARS OF REPLACING NUMEROUS ENGINE TUNE UP PARTS TO NO AVAIL, INSTALLED A NEW TORQUE CONVERTED AND IT SOLVED THE JERKING PROBLEM. I THINK I'LL HAVE TO DO THE SAME. byerjv@yahoo.com

Hi Everyone!!

I hope you're OK.

I have to admit - this is a VERY interesting topic for me. I've had that 'chugging' problem ever since I bought my 1993 LS400 in October of 2003. I have often described the feeling as if I was towing something. [And the weight of the imaginary thing trailing behind me was jerking the car as the wind hits 'it' - or something like that] A Lexus troubleshooter finally figured out [After I had already replaced several parts and cleaned the throttle body, etc., etc.] that it was a problem with my torque converter. He said [And this is going back a couple of years now - but my car still has the same problem because I can't afford to buy a new TC] that if I press on the brake pedal just enough to cause the brake lights to go ON [Which you can see - when it's dark out at least - in your rear view mirror as the third brake light reflects on the back window] the TC clutch will UNLOCK. When MY car is 'chugging' or 'jerking' at around 80 km/h [50 MPH] and I cause the brake lights to come on - the 'chugging' and/or 'jerking' instantly STOPS.

That said..... just around town - the car is fine - for the most part. And can accelerate quite quickly. But once the clutch starts to act up - the power from the engine TO the transmission is noticeably and negatively effected. [Or is that affected - I can never figure that out!!]

If you're still having the same problem - try that - and see what happens.

That said - I'd love to know if it's possible to unplug something and keep the TC clutch from engaging.

Craig!!

My 1991 (218K) is still doing it as well. Yes, it kinds feels like you are towing a small trailer and its bumping the car back and forward at certain speeds. I am not yet ruling out the engine/transmission mounts though since they are still the originals @ nearly 220K and I am also getting horrid vibrations!

If its the torque converter causing this "bumping" issue, I am NOT fixing it... I cant even imagine how many Ben Franklins (thats 100 dollar bills for you that dont live in the states) that will cost to repair on this junkyard fodder. I will sell it, junk it, donate it to charity and take a $4000 loss and give the Mercedes rather than the Lexus to my mother and buy me another car. I could have bought a nice 2001 LS for what I have spent/going to spend in repairs on this car!

Alot of people always says what "excellent" transmissions these cars have, but seems like I read alot about these torque converter issues lately. I hope thats not mine (or anyone elses here) problems.

I hate to have to complain and be a downer all of the time, but this car is really bumming me out. Seems like when I get one thing fixed, there is something else to replace. IF I can ever get ahead (this car is driving me to bankruptcy), I will replace the engine/transmission mounts and see if this clears up most of my problems (as some here have said it may).

I'm still having problems with the car "jerking" when the lock-up feature of the torque converter tries to engage at about 45mph. It comes and goes. Last week the car was fine, but it's been chugging again for four days now!!! I'm considering just disconnecting the electronic lock-up feature. Does anyone know exactly where it's located on a 1992 LS400? Is it attached outside the transmission? Is it easily disconnected? Thank you!

YES, IT STOPS CHUGGING/JERKING IF I PUT THE BREAK ON AND MAINTAIN 45 MPH USING THE GAS PEDAL. IF I TAKE MY FOOT OFF THE BREAK IT STARTS CHUGGING AGAIN. THAT'S WHAT I'D LIKE TO DO... DISCONNECT THE LOCK UP FEATURE OF THE TORQUE CONVERTER. I'M THINKING I'LL ASK MY MECHANIC. HAVE YOU TRIED DISCONNECTING IT YET?

Nobody seemd to ask if the R (reverse) light comes on when you use the brakes. If this is the case, it is a simple fix. Mine did exactly the same thing and it was caused by a broken wire in the trunk hinge. I spliced in a new section and everything was back to normal. Just a thought.

Mine did this when I got it (used), right around 45mph. It also hesitated off the line under light throttle.

I did a lot of maintenace, so it could have been a combination of many things but having the transmission fluid and filter replaced, cleaning the throttle body and having a tune up including new spark plugs and wires made it go away. The throttle body was the biggest improvement but the tune up finished the job.

Well, my '91 is still doing this and I hope with the tranny mount I am soon replacing will stop alot of it. If not, I am going to have the throttle body replaced and see if thats it. Mine seems to do it worse during the first 4 to 5 miles of driving when first driven for the day. I do also get that momentarily hesitation when I first accelerate too though. The car pulled out, it hits 1200 rpms, its like it hold back/hits a dead spot, then takes off again. Dont know if the problems are related though.

I have a 1991 LS 400 with 130K that has shown similar problems lately. I found this thread because I need to fix it, it is driving me crazy. About six months ago I replaced the power steering pump and had the alternator rebuilt. In the process I cleaned the throttle body and of course disconnected a few other things. Since then the missing or "chugging" has been pretty consistent throughout the gears and I have found that it does it less if I turn the overdrive button off. This changes the rpms (although I havent fixed the tach yet) you can feel it.

I always thought that it was fuel related, electrical or sensor related or that maybe moisture got into something when I cleaned the engine. I have run seafoam and other stuff to try and clean it but nothing. The only thing that helps is the overdrive. Sadly it makes me want to drive faster to keep it from missing which isnt good. I never thought about the transmission or tourque converter. I would be interested also in un hooking and seeing what happens. Any response to where the sensor is located? thanks for any advice

Well, mine is still doing it and honestly, it feels like the torque converter to me, but I hope not... I am hoping its either the tranny mount, or the throttle body. My transmission shifts smoothly in all gears, even when going into and out of lockup mode. Its mainly when changing between an incline or decline on light acceleration... it kinda jerks back and forth, almost like a bobble.

Hey just read this topic and well guess what exact same symptoms but in my car ls400 89 (celsior) i get the engine light and the trc off light goes on. At first it wasnt that bad, but now my car stalls at the lights. Sure its the torque convertors? anyone fixed it and found it is the answer?
oh and also i cant turn the trc on or off when its in this state too.

AFAIK, no one is really sure yet. I am not getting the engine light issue and my car dont have trac control, so I am not sure about that. I am going to try to get my throttle body cleaned soon and a new tranny mount and see what happens... if OK, then onto getting the PS leak repaired. Useless piece of junkyard fodder.

Just too let you know that in Australia these cars are going for about$10k private sales and from a import dealer $13-15k. Not chump change lol
Msut be different scenario in the US.

Even for a 90-94 LS/Celsior? They wanna buy mine for $4K?

After new spark plug wires, distributer caps and new throttle position sensor, my engine missing/chugging at 45-50 mph disappeared for 2 months. It has come back (but not nearly as bad) with the cold weather (40 degrees in the morning). I'm thinking it could be the thermistor which monitors the coolant temperature and once warm enough allows the transmission to shift into overdrive or the converter to go into lock-up. I think I'll let the car idle for 15 minutes before I drive and see if it still misses/chugs. Maybe the throttle position sensor setting has changed and needs to be reset. At any rate, my normal car mechanic is good and won't work on a Lexus. He says you fix one thing and something else breaks. I think this is the last Lexus I'll own. I like the car, but it's aggravating.

AMEN to those last two sentences you posted! Me too! I used to love my car, but all of these little annoyances that I cant repair myself, or cant afford to repair myself is so disappointing. Last LS I owned I said I would never own another, then I took a chance and bought this one. Fool I am. I honestly dont think I will ever buy another... not a gen 1 with high miles. If I ever do buy one, it will be a 2001-02 LS430 with good miles, but it will be awhile before I can afford that.

Anyway, there is another person on another Lexus site that mentions this issue. His LS is in the shop as we speak. He thinks its the transmission, so its in a transmission shop to be checked and will report back. I mentioned that I was most interested because his symptoms sounded like the issues I have. I will post his results.

I thought new transmission mount would help mine, but it didnt. I still even get that gear shifter "shake" at certain times at highway speeds, so I am at a loss as to whats going on (my Mercedes shifter is a still as a frog on a lilly pad lol.). I still get that "chug" or jerk on light acceleration as the grade of the road changes. I have been told it could be the throttle body needs cleaning, so I am going to have that done and see. My main concern now is the big loss of power steering assist (I have very little assist from the power steering). Most recently my car has started that ever-so-dreaded "clunking" from the front suspension on certain bumps in the road. It is so annoying and my last LS did this since day 1 I owned it and I really hated it. Seems like as soon as my car hit 224K, this started, which was the same mileage my old LS had about the time I bought it.

As I have said before the plan was to sell this car to my mom, but I am not sure I would pack this car off on her, but she still seems to think its a good car, but I would rather her buy my Mercedes and me sell the LS and buy me something else.

We will see. Good luck with your car, hopefully you can get yours up to par. I think mine is too car gone (for ME to bring back) and it only has 224K miles. I am sure that someone with the ability or money to get it back up to standard would enjoy this otherwise fine car.