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98 LS400, Transmission Hard Shifting

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Old 06-09-15, 11:39 AM   #16
johnnyg66
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I have had my 92 for 5 years. I have done everything this site has recommended doing to fix all the gremlins.

For the last bit my tranny shifts slow under heavy acceleration. Floor it and revs up goes than its like the brakes are on. Last a few seconds than catches up with a kick.

Done all things ecu/many drain and fills /new filter. Etc etc.

Last thing I did was adjust the kick down cable found it loose that helped some but not 100 percent.

Thinking of replacing the solenoids next.

But this car is practically new throughout.

My 2cents.
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Old 06-09-15, 01:49 PM   #17
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Did you adjust the cable at the transmission side or the engine side? These are basically the same tranny but with the added 5th gear. Good idea, let me know if you have any ideas.

I agree with the brakes on analogy. It is almost like when you hold a line lock and build revs to flash the torque converter to full lock up and let the button go and you are off.

It is that pause between the throttle stab and the car taking off that makes me wonder. Once it does take off it chirps the tires and scuffs them again in second, even with the tire pressure softened to factory spec.

The thing is a beast once it goes but it is dead off the line. I have no idea when it will actually start moving. Putting it in snow for smooth starts sucks. It drives like it is dragging my boat and trailer.

At least it is safe in parking lots and commuting. Need to find a capacitor to do the ECU test Yamae came up with.
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Old 06-09-15, 03:58 PM   #18
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On my 92 cable on top was adjusted not on the trans.
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Old 06-09-15, 07:03 PM   #19
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Johnny,

Yes I know which one you are talking about, I'll have to take the engine cover off the 2000 and see if it is similar. Do you remember if you took out a ton of slop, or just like a 1/4 turn or something?

Cables do stretch, so it makes sense to me.

Yamae,

The transmission shop owner that posted in this thread said that he had fixed a similar problem like mine with 98-2000 LS owners that had come in and he found a gear ratio code that was set on the transmission side of the ECM. He went on to say a code scanner that can get into the transmission side can clear this code. It is set when the power/snow switch or shifter is bumped while the computer is commanding a shift itself and detects slip in the trans and calls for full line pressure to protect the transmission. He says clearing the code works virtually every time.

1. Is there a separate trans computer and

2. Does the ECU have a code area for transmission faults or events like he mentions?

3. Can I reset the transmission codes by killing power to this area/computer or is it written on a chip like the odometer and have to be reset manually?

Any insight you might have would be greatly appreciated and also where I can buy a CD - ROM or online download able full shop manual. I have one for my Honda and has eliminated the need for me to go to the dealer except for a few small parts like o rings and special fasteners.

With the CD, I have the exact oem PN and Google and amazon get me to factory parts at 1/3 dealer.

Sorry for the long post! I just need to know I'd there are any options before I jump in and recap my ECU, as a replacement is not an option unless I get it reflashed at the dealer. Ouch!

Debbie

Last edited by PlatinumV8; 06-09-15 at 07:07 PM. Reason: clumsy thumbsie
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Old 06-09-15, 09:39 PM   #20
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Before I answer your questions, I must inform you that the snow mode does not use the 1st gear. The 2nd gear is used skipping the 1st gear when the car starts. In other words, there's no gear shift from 1st to 2nd.

>1. Is there a separate trans computer?

No. The main ECU controls both the engine and the AT. There's no separate computer for the AT.


>2. Does the ECU have a code area for transmission faults or events like he mentions?

The ECU has 2 different code areas. One is organized by a RAM and is erasable disconnecting the DC supply. The other is organized by a NVM (Non Volatile Memory). To erase it, you need a tool or a scanner. If a scanner doesn't read any code, it simply means that both memories don't have any stored data. Regarding the info from the AT guy, I need to talk to him some more to judge.


>3. Can I reset the transmission codes by killing power to this area/computer or is it written on a chip like the odometer and have to be reset manually?

Serious failure codes and some studied results can't be erased by the power disconnection.
I don't remember well the detail since my own memory is getting old and it erases the stored data automatically.
Since you don't get any code, I think the ECU is not detecting any failure or it is not capable to detect or store the code due to the ECU problem or stored codes were already erased.

Regarding the manuals.
Since many years have passed after coming back to Japan and I don't know much about the latest situations there in US regarding the availability of manuals. There are many kind American members here and I hope some one could pop in and answer your question about the manual.


I need to ask you below 4 items +1 to give you some more advise. Inform me the "rpm" of your engine at following conditions.

At the AT position "P".
1, Idle rpm when the engine is cold and just started.
2, Idle rpm when the engine is fully warmed up.

At the AT position "D" with brake pedal is pushed by your leg ( to give some load to the generator).
3, Idle rpm when the engine is cold and just started.
4, Idle rpm when the engine is fully warmed up.

Start your car and
5, at a speed bump or at an equivalent, slow down your car(down to 8mph) and after that, speed up to 20mph in 3 seconds. Does your tachometer jump up to more than 2400rpm and do you feel any unusual acceleration? I mean that the car run too slow at first then too much quick acceleration?

I need to know these 5 to see how the ECU is acting up.

Last edited by Yamae; 06-09-15 at 11:24 PM. Reason: To add about the snow mode at top.
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Old 06-09-15, 10:00 PM   #21
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I did have to dial it back some I went with the manual recommended adjustments. It had some slack and think it was set for softer shifts.
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Old 06-10-15, 09:13 AM   #22
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Quote:
Originally Posted by Yamae View Post
Before I answer your questions, I must inform you that the snow mode does not use the 1st gear. The 2nd gear is used skipping the 1st gear when the car starts. In other words, there's no gear shift from 1st to 2nd.

>1. Is there a separate trans computer?

No. The main ECU controls both the engine and the AT. There's no separate computer for the AT.


>2. Does the ECU have a code area for transmission faults or events like he mentions?

The ECU has 2 different code areas. One is organized by a RAM and is erasable disconnecting the DC supply. The other is organized by a NVM (Non Volatile Memory). To erase it, you need a tool or a scanner. If a scanner doesn't read any code, it simply means that both memories don't have any stored data. Regarding the info from the AT guy, I need to talk to him some more to judge.


>3. Can I reset the transmission codes by killing power to this area/computer or is it written on a chip like the odometer and have to be reset manually?

Serious failure codes and some studied results can't be erased by the power disconnection.
I don't remember well the detail since my own memory is getting old and it erases the stored data automatically.
Since you don't get any code, I think the ECU is not detecting any failure or it is not capable to detect or store the code due to the ECU problem or stored codes were already erased.

Regarding the manuals.
Since many years have passed after coming back to Japan and I don't know much about the latest situations there in US regarding the availability of manuals. There are many kind American members here and I hope some one could pop in and answer your question about the manual.


I need to ask you below 4 items +1 to give you some more advise. Inform me the "rpm" of your engine at following conditions.

At the AT position "P".
1, Idle rpm when the engine is cold and just started.
2, Idle rpm when the engine is fully warmed up.

At the AT position "D" with brake pedal is pushed by your leg ( to give some load to the generator).
3, Idle rpm when the engine is cold and just started.
4, Idle rpm when the engine is fully warmed up.

Start your car and
5, at a speed bump or at an equivalent, slow down your car(down to 8mph) and after that, speed up to 20mph in 3 seconds. Does your tachometer jump up to more than 2400rpm and do you feel any unusual acceleration? I mean that the car run too slow at first then too much quick acceleration?

I need to know these 5 to see how the ECU is acting up.

My 98 does as follows :-

1- 1400 rpm
2- 650 rpm
3- 1100 rpm
4- 300 rpm
5- i have this exact issue

thanks Matt
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Old 06-10-15, 11:52 AM   #23
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Johnny,

Thanks for the intel! I'll just take it a bit at a time. See how it drives and then adjust in increments.

Alien,

I was checking out the new posts late last night and found the the LS460 is plagued with the same kind of problems as our 98-2000. It is the VVTI system acting up after oil changes and other oil related issues. It seems there are small passages and screens that are incredibly sensitive to using non factory recommended oils or switching from conventional to synthetic.

I asked for recommendations about how it might impact the same kind of units on the LS400 and was told quite rudely, to get off their side of the board and go back where I belong.

My response was not without its own coarseness...

VVT-i is simply variable intake paths and variable valve timing.

In the old days like my Mach 1 Mustang, you had 4BBL heads for racing and 2BBL heads for street driving. Our hesitation is exactly what you feel when you have a 4BBL head car in gear with idle rpm and you floor the accelerator. Nearly nothing happens. The tach slowly rises and hardly any sound from the motor. Then as the revs build above 3K the engine comes to life and tosses you back.

Heel toe shifting back then was mandatory, because you needed to keep the sky high revs or the car would fall on its face when you let the clutch out.

The VVT-i system from what the LS460 owners that are nearly being rear ended entering freeways on the OTHER SIDE of this board, say oil flow runs the system. It is hydraulic fluid basically.

So when we floor it or go to part throttle at slow speeds and the engine is on the 4BBL profile, you will be stuck going next to no where or lurch when the blockage or flow is cured as pressure builds.

I'd say, based on other complains OVER THERE, it can also get stuck in 2BBL mode where the car falls on its face over 4k, like a big block carb motor with a street cam. Rev it all you want, it won't go any faster and you will break things.

Motors are motors, and these are all Quad Cam 32V V8s. No matter what Devh, thinks of LSs without a 460 designation.

Last edited by PlatinumV8; 06-10-15 at 12:05 PM.
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Old 06-10-15, 11:58 AM   #24
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Yamae,

Thank you for your time and help. I will get you those numbers ASAP, here on the forum.

Also, since Audi did an oil change and valve cover gasket replacement before I picked up the car, is it plausible the VVT-i system could be involved. I'm searching for a service manual on CD now.

I'm quite sure your memory losses are for useless data to make room for virtual memory! I've a few friends in the auto shop racket, I'll see if they have experience getting into the ECU on these cars.

Looked for that cap to do the test today. Radio Shack is torn down for good here.

Debbie
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Old 06-10-15, 02:51 PM   #25
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Quote:
Originally Posted by PlatinumV8 View Post
Johnny,

Thanks for the intel! I'll just take it a bit at a time. See how it drives and then adjust in increments.

Alien,

I was checking out the new posts late last night and found the the LS460 is plagued with the same kind of problems as our 98-2000. It is the VVTI system acting up after oil changes and other oil related issues. It seems there are small passages and screens that are incredibly sensitive to using non factory recommended oils or switching from conventional to synthetic.

I asked for recommendations about how it might impact the same kind of units on the LS400 and was told quite rudely, to get off their side of the board and go back where I belong.

My response was not without its own coarseness...

VVT-i is simply variable intake paths and variable valve timing.

In the old days like my Mach 1 Mustang, you had 4BBL heads for racing and 2BBL heads for street driving. Our hesitation is exactly what you feel when you have a 4BBL head car in gear with idle rpm and you floor the accelerator. Nearly nothing happens. The tach slowly rises and hardly any sound from the motor. Then as the revs build above 3K the engine comes to life and tosses you back.

Heel toe shifting back then was mandatory, because you needed to keep the sky high revs or the car would fall on its face when you let the clutch out.

The VVT-i system from what the LS460 owners that are nearly being rear ended entering freeways on the OTHER SIDE of this board, say oil flow runs the system. It is hydraulic fluid basically.

So when we floor it or go to part throttle at slow speeds and the engine is on the 4BBL profile, you will be stuck going next to no where or lurch when the blockage or flow is cured as pressure builds.

I'd say, based on other complains OVER THERE, it can also get stuck in 2BBL mode where the car falls on its face over 4k, like a big block carb motor with a street cam. Rev it all you want, it won't go any faster and you will break things.

Motors are motors, and these are all Quad Cam 32V V8s. No matter what Devh, thinks of LSs without a 460 designation.
I find that appalling for other LS forum members having that bad attitude, at the end of the day we all driver lexus, incidentally i have had that wont rev over 4k at 50mph kickdown, only occasionally though. MATT
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Old 06-10-15, 07:55 PM   #26
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Quote:
Originally Posted by alien1974 View Post
My 98 does as follows :-

1- 1400 rpm
2- 650 rpm
3- 1100 rpm
4- 300 rpm
5- i have this exact issue

thanks Matt
I bet your throttle body and the air mix path are clogged badly. Due to the clogging, the amount of air which passes through the limited opening of the throttle valve is quite limited and the data table in the ECU is out of the range. The ECU is confused and it can't control the engine rpm well enough and also the gear selection is not done properly.

Following links might be useful for you to fix your issues.
https://www.clublexus.com/forums/ls4...ml#post8906720
https://www.clublexus.com/forums/ls4...ml#post8164859
https://www.clublexus.com/forums/ls4...les-on-it.html
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Old 06-11-15, 09:17 AM   #27
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Quote:
Originally Posted by PlatinumV8 View Post
Johnny,

Thanks for the intel! I'll just take it a bit at a time. See how it drives and then adjust in increments.

Alien,

I was checking out the new posts late last night and found the the LS460 is plagued with the same kind of problems as our 98-2000. It is the VVTI system acting up after oil changes and other oil related issues. It seems there are small passages and screens that are incredibly sensitive to using non factory recommended oils or switching from conventional to synthetic.

I asked for recommendations about how it might impact the same kind of units on the LS400 and was told quite rudely, to get off their side of the board and go back where I belong.

My response was not without its own coarseness...

VVT-i is simply variable intake paths and variable valve timing.

In the old days like my Mach 1 Mustang, you had 4BBL heads for racing and 2BBL heads for street driving. Our hesitation is exactly what you feel when you have a 4BBL head car in gear with idle rpm and you floor the accelerator. Nearly nothing happens. The tach slowly rises and hardly any sound from the motor. Then as the revs build above 3K the engine comes to life and tosses you back.

Heel toe shifting back then was mandatory, because you needed to keep the sky high revs or the car would fall on its face when you let the clutch out.

The VVT-i system from what the LS460 owners that are nearly being rear ended entering freeways on the OTHER SIDE of this board, say oil flow runs the system. It is hydraulic fluid basically.

So when we floor it or go to part throttle at slow speeds and the engine is on the 4BBL profile, you will be stuck going next to no where or lurch when the blockage or flow is cured as pressure builds.

I'd say, based on other complains OVER THERE, it can also get stuck in 2BBL mode where the car falls on its face over 4k, like a big block carb motor with a street cam. Rev it all you want, it won't go any faster and you will break things.

Motors are motors, and these are all Quad Cam 32V V8s. No matter what Devh, thinks of LSs without a 460 designation.
I saw nothing in Devh response that would lead me to believe that so don't take these things personal. Heck you will get crazier responses right here in this forum. Just keep searching and asking questions. Yamae is probably your best bet but I had similiar though not the same issues. I cleaned the MAF and eventually changed my drivers side OCV which helped alot.

Quote:
Originally Posted by alien1974 View Post
I find that appalling for other LS forum members having that bad attitude, at the end of the day we all driver lexus, incidentally i have had that wont rev over 4k at 50mph kickdown, only occasionally though. MATT
Like I said there are plenty bad attitudes right in this forum.
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Old 06-11-15, 10:53 AM   #28
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I cleaned the air mix path, maf, and throttle body a month or so ago, using the correct cleaning products
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Old 06-11-15, 01:29 PM   #29
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I cleaned the air mix path, maf, and throttle body a month or so ago, using the correct cleaning products
I've done it multiple times. And had my injectors cleaned by the dealer (the chemical flush, not ultrasonic cleaning). No change whatsoever. It always seems like it's better for a day but I think that's more of a false positive.

The only thing I haven't done is replace ecu caps and take the throttle body completely off and clean it as well as behind it. I plan on doing it someday. Hopefully it'll help something.
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Old 06-11-15, 09:35 PM   #30
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Yamae,

Tests all done at four hours after parking car from commute home, no accessories on but daytime running lamps.

Idle in P cold at 70 F ambient air temp : 950 rpm (Best guess)
Idle in D with foot on brake same start up out side temp : 600 rpm (Best guess).

Idle in P fully warmed up : 600-700 rpm The needle fills the empty spot exactly on tach.
Idle in D fully warmed up : 300-400 rpm The needle is steady between 2nd and 3rd hash mark.

I'm beginning to think dirty intake plumbing or oil control valves and their screens.

This weekend I have flash flood warnings in my area, so no working on cars. May have to move them at a moments notice.

BTW, The temp gauge reads right in the middle of the range at full warm up.
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