ck90211

New owner of 95 LS w/150K miles, so my issue may be a none issue.

At faster speed (40mph+), when I lift off gas suddenly, the car feels like it lunges forward before slowing down (like the tranny is just fraction of a second behind the foot). Is this something normal with LS or drive by wire kind of car? Always had direct linkage accelerator in other cars, or low power drive-by-wire models (hybrids). So need some guidance. Thanks.

Lust4Lexus

it might be the torque converter. (non- issue)

91LS400LEX

Could be your transmission mount. Its cheap and easy to replace. Do that first. @ 150K, if its never been done, its probably time.

My 1991 LS400 would jerk at low acceleration at certain speeds. I thought it was a torque converter and part of the issue was the transmission mount, but a dirty throttle body was part of the issue. After a new tranny mount, it helped alot and a throttle body cleaning took care of it completely.

7schulz

I have the same issues no concrete answer yet, could be ECU with a bad program 95's have. When you find an answer let me know. If you search I have a thread or two about this issue.

https://www.clublexus.com/forums/ls4...will-jerk.html

https://www.clublexus.com/forums/ls4...-95-ls400.html

I have found if you think about it and slide your foot off instead of pulling it off fast it doesn't happen.

http://www.alldatadiy.com/TSB/31/95310210.html
EG00396 OCT 96

ck90211

7shulz, you are right, if I feather off gas pedal it is very smooth, only happens when I lift off quickly (like when someone cuts me off, etc..). Will give trainny mount replacement a try first since it's cheap and quick to replace. This isn't a big driving issue, just afraid it might lead to something big (like transmission metldown).

7schulz

It doesn't do it if you have the CC set and use the cruise to cancel it. I don't think its tranny mounts but can't hurt to replace. I think it has something to do with lock up in the torque converter and not getting out of lock up when the engine idles down to fast after you let off the gas. Which would lead to the ECU which is probably the case. I have asked on here if we can use a 96 or 97 ECU to take care of it. I also found a place to reprograms ECU's but they couldn't tell me if there program had the fix or not. Seems like more 95's are popping up with this issue recently. I also found a junk yard that has a 95 ECU but had a date of 2005 so maybe that car had the upgrade ECU from the TSB done. I might give that a try.

ck90211

Funny you mention 96-97, because I test drove a 98 before buying the 95, and the '98 doesn't feel as harsh.

7schulz

98 is a different engine vv-ti
All being the same get the 98, my 95 was too good of a deal to pass up.

Oops I read that wrong, went all dislexic.
I would think the ECU would be the same for 95-97, and 96-97 should have the correct program in it. All else in the vehicle is the same as far as I know. If you can get your hands on a 96-97 and it works let me know.

Amskeptic

In the other thread I mentioned that the torque converter lock-up may not be releasing quickly enough when you release the accelerator. This gives you high-compression V8 engine braking for an instant. Throttle position switch is responsible for signalling the solenoid. Moving the switch clockwise as you face the rear the car will signal the torque converter release a tad sooner.
A totally fun and easy test of this being the problem, is to lightly apply the brake with your left foot (no need to drag the brakes, just get the pedal down far enough to trip the brake lights) while underway, and then release the accelerator quickly. If no herky jerky from the engine, there you are. You see, when the ECU determines that the brakes are on, it automatically releases the torque converter by means of cutting off the voltage to the throttle position switch.
Colin

7schulz

Do you have a picture of the TPS so I know what the heck I'm looking at? I'll probably test this theory on the way to work tomorrow and if it works I'll try the TPS.

Amskeptic

Let's use the power of the language to "create" a picture.

You know where the throttle cable pulls open the throttle plate by means of a "throttle lever"?
This throttle plate pivots on a shaft called the "throttle shaft".
If you can rev the engine inside the engine compartment by pulling on the "throttle lever", you cannot help but see the throttle position switch, because it is just on the other side of the "throttle body", attached to the very same throttle shaft as the the throttle lever.
Colin

7schulz

Amskeptic - I tried your partial brake while cruising and letting off the gas, and you were right. I drove normally and let off and it jerked. Then I put on the brakes just enough to see the tail light, light up and let off the gas in the same manner and no jerk. Guess tonight I will have to check the TPS. A picture would still be great if someone has one. Otherwise I should be able to figure it out.