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Transmission Hesitation?


j4649
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Hi I purchased 99 LS400 with 111k miles a week ago, So I don’t know much about this car. However, I just noticed that the car has transmission hesitation when giving it gas after I slow down to almost a complete stop. There is a hesitation up to 1500rpm then suddenly start moving. Throttle seemed responding but transmission is not engaging up to 1500rpm..... Otherwise up shift and down shift is smooth. So I just did Trans fluid flush with T-IV, Drain and fill 3 times. It was dirty However, nothing changed so far. Does it need any update on ECU or need reset?? or new transmission?? Hope someone can help me out... Thanks :)

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I have also been experiencing this problem with my 1998 LS400 - 92k miles. When I slow down to between 5-10mph, the car hesistates to accelerate again. Otherwise the transmission operation is smooth. So far I haved drained and filled my transmission, and reset the ECU for the car. I'm wondering if anyone else has had this problem?

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It's common, and normal actually. The LS went to fly-by-wire setup in 98', and instantly created a "moment of confusion" in the transmission from the gas peddle while the computer thinks about what you're asking it to do. It's normal, and most folks find that after a while with the car, they've adapted to it and don't really notice anymore. All Toyota's do this, even the ones being built today. Infact, I think the EPA is requiring it on all new cars now, as it seems to reduce pollution. I know our 07 Mazda 3 has the fly-by-wire setup too, but it isn't nearly as bad as Toyota's. I hear most complaints about it from ES and IS owners, especially the IS, as they tend to drive a bit more aggressively. My 4runner does it, my folk's solera convt. does it, friends ES330 does it, neighbors new camry does it.

But it began in 98' for the LS when the new VTI engine was introduced to the car.

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I have also been experiencing this problem with my 1998 LS400 - 92k miles. When I slow down to between 5-10mph, the car hesistates to accelerate again. Otherwise the transmission operation is smooth. So far I haved drained and filled my transmission, and reset the ECU for the car. I'm wondering if anyone else has had this problem?

Question, After you did drain and fill ATF and reset the ECU, do you feel any better? or same?

It is hard to accept for me that is normal things on LS400..... <_<

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Yeah, it started in 98' with the new engine, and the new transmission (5 gears instead of 4).

You can swing by a dealership and ask if they have any updates for the softward and reflash the ecu, but to my knowledge, I don't think they do. But throttle lag has been a sore spot for Toyota cars for nearly 10 years now. It's better, but still there.

You want to experience some serious throttle lag though, go test drive the new Chevy Malibu. That think must have a Nintendo 64 computer in there.

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Question, After you did drain and fill ATF and reset the ECU, do you feel any better? or same?

It is hard to accept for me that is normal things on LS400.....

I didn't notice a difference after draining and filling the tranny fluid with T-IV. However, when I reset the ECU, the problem seemed to go away for a bit (a day), and come back later. I'm convinced that there may be a fix for this, but haven't really looked into anything yet. Since, not a lot of 1998+ LS400 owners have been discussing this issue, I feel that other owners may not have this problem.

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Actually, it's been discussed quite a lot, but just not in a dedicated thread setting. It's mostly been odd comments here and there for the LS. But most of the folks who have noticed it usually notice their driving technique simply adapts to it over a little bit of time. If you find a permanent fix, please post it up for everyone else to see! I'm sure that would become a sticky on the top of the index page!

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Thanks for your info

My LS is feel not throttle lag, more like transmission engage delay....

The engine RPM is going up but car is not moving till RPM reach around 1500rpm...

what I feel is same as throttle lag???

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Thanks for your info

My LS is feel not throttle lag, more like transmission engage delay....

The engine RPM is going up but car is not moving till RPM reach around 1500rpm...

what I feel is same as throttle lag???

Are you saying when you put the car into drive from park? or when you're already in drive, the engine revs but the transmission doesn't catch until you hit the 1,500 rpm mark? If it's slipping, then you're probably due for some fresh toyota oem fluid. if you think you have anything but oem fluid in there, then I would suggest a visit to your dealership for a flush. If you do have oem in there, but it looks brownish on the stick, then I'd do a search for "drain n' fill" to learn the easiest service you can possibly do to the car.

But eitherway, the computer hunts on that car a bit. It's not nearly as bad as others, even far more later models. A very good buddy of mine has an 03 or 04 IS300 in Florida. It's so bad on his, that he nearly got T-boned when he first got it trying to jet out into traffic. He said GO...the car said "WAIT, I'M NOT READY, I'LL GO WHEN I WANT". Last I heard, he was drafting a formal complaint "he's a lawyer" to Lexus and the dealership for ignoring his numerous requests for assistance. That was a few months ago. He still has it though, and says he's learned to understand how to drive it to minimize the effect.

It seems like every toyota product has one goofy flaw that drives people nuts. Just be glad you don't have a GX470, or 4runner, that all have a notorious Clunk in the driveshaft from a sticky slider-sleeve, that makes you think you've been rearended when coming to a stop at the stop light.

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Thanks for your info

My LS is feel not throttle lag, more like transmission engage delay....

The engine RPM is going up but car is not moving till RPM reach around 1500rpm...

what I feel is same as throttle lag???

Are you saying when you put the car into drive from park? or when you're already in drive, the engine revs but the transmission doesn't catch until you hit the 1,500 rpm mark? If it's slipping, then you're probably due for some fresh toyota oem fluid. if you think you have anything but oem fluid in there, then I would suggest a visit to your dealership for a flush. If you do have oem in there, but it looks brownish on the stick, then I'd do a search for "drain n' fill" to learn the easiest service you can possibly do to the car.

But eitherway, the computer hunts on that car a bit. It's not nearly as bad as others, even far more later models. A very good buddy of mine has an 03 or 04 IS300 in Florida. It's so bad on his, that he nearly got T-boned when he first got it trying to jet out into traffic. He said GO...the car said "WAIT, I'M NOT READY, I'LL GO WHEN I WANT". Last I heard, he was drafting a formal complaint "he's a lawyer" to Lexus and the dealership for ignoring his numerous requests for assistance. That was a few months ago. He still has it though, and says he's learned to understand how to drive it to minimize the effect.

It seems like every toyota product has one goofy flaw that drives people nuts. Just be glad you don't have a GX470, or 4runner, that all have a notorious Clunk in the driveshaft from a sticky slider-sleeve, that makes you think you've been rearended when coming to a stop at the stop light.

It happen when giving it gas after I slow down to almost a complete stop for turning rigth or left. the transmission doesn't catch until rpm hit the around 1,500 rpm.... that is why I feel more tranmission issue than throttle lag. I just did Fluid Flush (drain and fill 3 time with T-IV) but sitll same...

Is this Normal or has issue???

Thanks!

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Thanks for your info

My LS is feel not throttle lag, more like transmission engage delay....

The engine RPM is going up but car is not moving till RPM reach around 1500rpm...

what I feel is same as throttle lag???

Are you saying when you put the car into drive from park? or when you're already in drive, the engine revs but the transmission doesn't catch until you hit the 1,500 rpm mark? If it's slipping, then you're probably due for some fresh toyota oem fluid. if you think you have anything but oem fluid in there, then I would suggest a visit to your dealership for a flush. If you do have oem in there, but it looks brownish on the stick, then I'd do a search for "drain n' fill" to learn the easiest service you can possibly do to the car.

But eitherway, the computer hunts on that car a bit. It's not nearly as bad as others, even far more later models. A very good buddy of mine has an 03 or 04 IS300 in Florida. It's so bad on his, that he nearly got T-boned when he first got it trying to jet out into traffic. He said GO...the car said "WAIT, I'M NOT READY, I'LL GO WHEN I WANT". Last I heard, he was drafting a formal complaint "he's a lawyer" to Lexus and the dealership for ignoring his numerous requests for assistance. That was a few months ago. He still has it though, and says he's learned to understand how to drive it to minimize the effect.

It seems like every toyota product has one goofy flaw that drives people nuts. Just be glad you don't have a GX470, or 4runner, that all have a notorious Clunk in the driveshaft from a sticky slider-sleeve, that makes you think you've been rearended when coming to a stop at the stop light.

It happen when giving it gas after I slow down to almost a complete stop for turning rigth or left. the transmission doesn't catch until rpm hit the around 1,500 rpm.... that is why I feel more tranmission issue than throttle lag. I just did Fluid Flush (drain and fill 3 time with T-IV) but sitll same...

Is this Normal or has issue???

Thanks!

I have a similar issue on my 2000 ls400. It's seems to slip more often after i make a turn. I've flushed the tranny oil with IV fluid and it seems to be somewhat better. On my '94 ls, the accerelation was much more linear and there was no lag whatsoever. The breaking was also much more intuititive on the '94 ls than my current '00.

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right after I did ATF Flush, it was same as before. However, I keep driving and it seemed got better.

I guess transmission fluid was dirty and when turn somehow line was clogging or something.

Just in case, I will remove transmission oil pan and clean/replace filter and clean pan soon.

Thanks for your help. :)

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Turn the power button on and make sure you use the highest grade fuel you can get and it will reduce the issue.

BTW the 7 series drive by wire was the worst ever system for lag and tranny confusion i have driven to date . It was a 03 7 series.

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I have a 91, and after getting it, I did a couple of AT drain and fills, replaced the filter, etc. No problems existed, I was just trying to bring it up to good maintenance standards.

When filling the AT after doing the filter change (remove pan, etc.), I filled based on the dipstick (which I've found unreliable), which I noticed meant I put in 1 qt less than I had drained out.

During the subsequent test drive, I seemed to notice the exact problem you mention. It seemed definitely wrong. I then added a qt of ATF. It now drives perfectly, and the dipstick indicates that it is overfilled.

I'd recommend putting some more ATF in. Of course always Type T-4. If you're cautious, just fill to the top of the dipstick line. If braver, try a little past that.

Oldskewel

91 LS400, 162k miles

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  • 6 years later...

My new to me 1999 does this.

How can one tell the difference between a slipping transmission and this issue? It definitely feels transmission related. Press the pedal, rpm's rise, delay, then it moves forward. If it were throttle lag, the delay would be between the pedal press and the RPM's rising.

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Joe, I had those symptoms in my 98 after I drained two quarts and refilled the tranny. Only it really drained about three quarts and was then slightly low. The tranny would slip until I got to higher RPMs and was especially bad when cold. I added a quart of T4 fluid to bring it up to the proper level and it quit slipping.

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Hi I purchased 99 LS400 with 111k miles a week ago, So I dont know much about this car. However, I just noticed that the car has transmission hesitation when giving it gas after I slow down to almost a complete stop. There is a hesitation up to 1500rpm then suddenly start moving. Throttle seemed responding but transmission is not engaging up to 1500rpm..... Otherwise up shift and down shift is smooth. So I just did Trans fluid flush with T-IV, Drain and fill 3 times. It was dirty However, nothing changed so far. Does it need any update on ECU or need reset?? or new transmission?? Hope someone can help me out... Thanks http://us.lexusownersclub.com/forums/public/style_emoticons/#EMO_DIR#/smile.gif

I have fixed this problem for several cars so far and every car is running as is new.

Believe it or not, it is caused by the clogged throttle body and the clogged air mix path for injectors.

Cleaning them well will fix the problem.

LS400/Celsior after 98 does not have a IACV. The main throttle valve controls the air flow from the idle to the max power. When the throttle body is clogged too much, the ECU is confused and your type of symptoms occur as results.

The link below may help you to act some more with photos.

http://www.clublexus.com/forums/ls400/612441-still-low-idle-in-drive-at-stop-what-you-think.html#post8164859

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