Transmission Lurch

[blake918]

My '95 LS gives a nice big lurch foward when I put the car in D or R. This is a very strong lurch...the car kinda recoils a little after the lurch(just to give yall an idea of how strong the lurch is). The tranny shifts through all of the gears flawlessly-down and up shifts are superb and smooth. The car idles perfectly smooth and runs like a top. Any ideas on what might be causing this lurch. I'm in the process of changing all of the tranny fluid; I drained two quarts on Sunday, and refilled with 2 quarts of Toyota T-IV. The shifts got even smoother, but the lurch is still here. The funny thing is the lurch is pretty much non existant once the car is warmed up.

[445187]

<_<

Ditto, same year, same prob, reverse too, can't wait to hear!

[VMF]

same here...

but i dont get it all the time

[93LSOwner]

Blake, I think I asked this question like two times before; and didn't get the answer. Lets see...... :(

[99lsguy]

blake,

Just called local independent lexus shop - they are very good - this is what they say:

All 95-97 LS owners have a similar complaint. The shop feels like it is due to the "higher idle" rpms that Lexus incorporated into the 98-97 design. On cold engine startup, rpms can go around 1800-2000! In about a minute or so, engine should "kick down" to around 12-1300 rpms, ANOTHER minute + and another kick down to 700-900 rpms.

They know of your problem/complaint from many other customers who own 95-97 model year LS.

Since you've said that the problem goes away after warming up (low 700 idle) - this seems to hit the nail on the head!!!

90-94's had lower ( 1300 rpms on startup) as does my Gen III ( 98-00) which has about 1200 rpms on startup. May I say it - sounds like a DESIGN FLAW for the Gen II LS's -

But not to worry, they say no damage can result - just annoying!!!

Anyway, check out the startup idling and time it out - see what happens to your car. Then wait at least until car is in 1200 rpm range for one test, and wait till it kicks all the way down to 800 or so for another. Let us know !

Good news is that you've got the right car for such a warm climate you're in!! should get to operating temp pretty quick!!

[VMF]

my startup idle rms are pretty high around 1300 rpm, but i have this problem even when engine is worm and rpms are around 600 i still get this kick

[99lsguy]

my startup idle rms are pretty high around 1300 rpm, but i have this problem even when engine is worm and rpms are around 600 i still get this kick

Does this (and perhaps every Tranny) have "steering linkage"???

Sounds like worn or loose connection??? Maybe from the shifter to the tranny??

[99lsguy]

Okay - been reading up on this.................

Every diag I've got about "harsh engagement" on the A650E tranny points to these parts in order:

1. Accumulator Control Valve

2. Solenoid Modulator Valve

3. c1 accumulator for Neutral to Drive

4. c2 accumulator for Neutral to Reverse

5. ECM

These are specific to Publication # RM579U................I don't have it :(

Blake, if your 95 is OK after she's up to op. temp.....then I think you're OK!

See what more of those pan drains do......and.......make sure your refill of fresh T-IV in only on the COLD / LOWER mark to start. This may be less than what was drained out, but don't go any higher than that until you've driven a few miles and got the LS up to temp. Then recheck, if its anywhere on the HOT marks (even the lower side) don't add anything. If you do have to add, only 2-4 ounces at a time!!!!

Run it for another day and check again - That T-IV expands all over the place , so give it time.......

[fromundr]

I have a 96 ls400 with about 140000 on it and it is currently doing the same thing when cold and stops once it is warm. I noticed that if the tap on the gas pedal before shifting, it won't do it. Give it a try.

As for the cause of the problem I have read that there is a Techniacl Service Bulletin for this model, here is what it says:

TSIB

Introduction Early Production 1996 Model Year LS 400 vehicles may experience an engine idle speed

reduction just before stopping the vehicle after a continuous long drive. To correct this

condition, the ECM logic has been changed.

Early production 1996LS 400 with VINs before JT8BH22F3T00414045

Parts : Previous part- 89661-50302 New Part- 89661-50303 Part Name ECM

Warranty info

OPCODE DESCRIPTION TIME OPN T1 T2

895011 LS 400 Driveability Improvement 0.8 89661-50302 08 71

Warranty Coverage 4years or 50,000 Miles

This is what the Bulletin says

I found this in another thread so I give credit to Big50Daddy.

Anyway some people claim that once the ecm was switched out, both the idle problem and the lurching were fixed!!

I will try and change the ecm out this summer see how it works. Do a seach and you will find more info on this.

Hope this helps!!

[pachocco1]

My '95 LS gives a nice big lurch foward when I put the car in D or R. This is a very strong lurch...the car kinda recoils a little after the lurch(just to give yall an idea of how strong the lurch is). The tranny shifts through all of the gears flawlessly-down and up shifts are superb and smooth. The car idles perfectly smooth and runs like a top. Any ideas on what might be causing this lurch. I'm in the process of changing all of the tranny fluid; I drained two quarts on Sunday, and refilled with 2 quarts of Toyota T-IV. The shifts got even smoother, but the lurch is still here. The funny thing is the lurch is pretty much non existant once the car is warmed up. Please help!!!!!

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Just wondering if your problem still persists. I have the same problem on my 97 and am curious to what the root cause(s) is/are. My thoughts are away from the the transmission and towards another area(s). My car has been dealer serviced for 90,000 miles and shifts flawlessly while in motion. I cant help but think something is flexing (a differential bushing or driveshaft coupling) and allowing the driveline torque (at the higher cold start rpm) to impact the vehicle position forward slightly.

[blake918]

Yeah, I still have the problem; I never really tried fixing it other than T IV pan drains every 5k . These days(that post was about 25k miles ago) it seems as if the shift from P to R has smoothed out, but the lurch is still there when I go from P to D when the engine is cold. I've adopted a method of releasing the brake immediately after I shift to D, so the lurch gets lost in the foward motion of the car; it really minimizes the lurch-it's worth a try. ;)

RW, great work with all of the research(I need to note my start-up rpms)! Thanks! :D

[monarch]

I don't know if this could apply to the LS, but in years past "lurches" when shifting into Reverse or Drive when the engine was idling high in the morning were caused by worn drivershaft universal joints.

Obviously new LS's didn't lurch (or else no one would have bought them)

so something must be worn on your particular car .

[Lexusfreak]

Yeah, I still have the problem; I never really tried fixing it other than T IV pan drains every 5k . These days(that post was about 25k miles ago) it seems as if the shift from P to R has smoothed out, but the lurch is still there when I go from P to D when the engine is cold. I've adopted a method of releasing the brake immediately after I shift to D, so the lurch gets lost in the foward motion of the car; it really minimizes the lurch-it's worth a try. ;)

RW, great work with all of the research(I need to note my start-up rpms)! Thanks!  :D

←

I wonder if using Amsoil synthetic ATF would help out a little more? Just a suggestion. ;)

http://www.amsoil.com/storefront/atf.aspx

[nc211]

I've got a 95 as well, does the exact same thing. I've had the ecu changed to fix that 40mph buckling, and it still lurches, so that didn't fix it. I am in the process of replacing my differential bushings as one is torn pretty bad. The differential when shifted into gear flexes quite a bit due to the torn bushing. Once I finally have it fixed "it's a pain in the tail to get the old ones out" I'll post up on what it did. I agree with monarch, it's something flexing too much in my opinion. I think it's either these bushing mounts, or the flex couplings between the drive shaft units, or both.

[flash213]

I've got a 95 as well, does the exact same thing. I've had the ecu changed to fix that 40mph buckling, and it still lurches, so that didn't fix it. I am in the process of replacing my differential bushings as one is torn pretty bad. The differential when shifted into gear flexes quite a bit due to the torn bushing. Once I finally have it fixed "it's a pain in the tail to get the old ones out" I'll post up on what it did. I agree with monarch, it's something flexing too much in my opinion. I think it's either these bushing mounts, or the flex couplings between the drive shaft units, or both.

←

Any improvements after changing the diff. bushings? Any other thoughts?

[blake918]

I don't know if this could apply to the LS, but in years past "lurches" when shifting into Reverse or Drive when the engine was idling high in the morning were caused by worn drivershaft universal joints.

←

That's a good suggestion, but the car is totally smooth going in to gear after it's warmed up. Wouldn't a worn u joint or bushing make a jerk all the time? <_< Any thoughts?

[nc211]

Flash, good timing on your question. The car is at the shop today to have all the rear control arms, struts and those rear differential bushing replaced. I'll let you know the results soon. They're a real booger to get out on your own. It's beginning to be seen by a lot of us that the drivers side bushing gets the brunt of the force from the differential. I also think it might be the propeller shaft's flex couplings. I agree with Blake's response as well, but I'm wondering if the high rev's simply put too much force on the worn out couplings, more so than the lower revs would.

Hopefuly the mechanics will get the bushings replaced today and I'll post up the results. I'm also getting hard up shifts now too, like their is a gap somewhere in the line causing a thump whenever the pressure changes down the drive line.

[JPI]

Blake,

Make sure your engine mounts and transmission mount are in good condition. Also there are two bushings in the rear diff, We never see the U joints on the lexus go out ever. Also you might want to look at the kick down cable. Give us a ring if you can't figure it out.

JP Importz

[nc211]

JPI, I'm curious, do you see a lot of those differential mounting cushions "bushings" go bad? The dealership guy told me almost never, but I didn't have the utmost confidence in his diagnosis. Seemed to be a young guy straight from training. Said my "clunking" noise in the front was actually my brakes! I'm tempted to take the car over there this week and show him my new control arms I put on myself and invite him to drive it for himself....no more clunking. I'm having my diff. bushings replaced today, driver's side is torn pretty badly. I've got 99,500k miles on my 95.

[VBdenny]

My cars gives a good jerk when you put it in gear right after start up. I thought it was normal. Once when our cat was sick and my wife was in a hurry to take it to the vets, she started the car and threw it in reverse. We now have two (posi) burnout marks in our garage.

[nc211]

Fixed! Just got it back, started it when it had been sitting for a while, idle was high, put it in gear, and a very noticable REDUCTION in that lurch. Now I'm not sure if it was the struts, strut rods or diff bushing because I had every control arm in the rear replaced, plus new struts in conjunction to the diff bushing. But, she's a smooth as glass now. No wobble, no shimmy. I did look at the old diff bushings, the driver's side one was damn near ripped in two. Car feels much much tighter. They did have to remove the rear differential however to get them out, but said it was only a 2.5 hour job. Total bill for 6 control arms, 2 struts and 2 rear diff bushings....$630

Not bad if you ask me. 10 old parts removed, 10 new ones put on. I'm ready for another 100k. Blake, I'm comin' for ya' son! :D

[nc211]

forgot....that bill also included a 4 wheel alignment.

[JPI]

JPI, I'm curious, do you see a lot of those differential mounting cushions "bushings" go bad? The dealership guy told me almost never, but I didn't have the utmost confidence in his diagnosis. Seemed to be a young guy straight from training. Said my "clunking" noise in the front was actually my brakes! I'm tempted to take the car over there this week and show him my new control arms I put on myself and invite him to drive it for himself....no more clunking. I'm having my diff. bushings replaced today, driver's side is torn pretty badly. I've got 99,500k miles on my 95.

←

The rear diff bushings do go out. I'm a young guy myself but I do know my lexus <_< .

JPI

[nc211]

Man you must, you're recommended by a LOT of people on this site!

You ever head out my way, let me know!

[flash213]

nc211 Which two control arms did decide to not to replace ? Was that $630 for labor ? At what mileage did you start to see the "ride" go? Curious for myself down the road.