Lexus IS Forum banner

auto tranny expertise

1K views 10 replies 9 participants last post by  SeattleSheila 
#1 ·
First, can/should the Forum Password echo astericks (sp?) instead of display in the clear? Our posting password does that...

Now for the real question. I remember rather recent posts about "abnormal" shifting, perhaps somewhat related to cold trannies. I even replied to one post about tranny hunting when exiting corners where I said that's what the "DOWN" buttons are for! I have felt a few inappropriate shifts but I have to admit that I can blame every single on of them on my own inattentive or incorrect throttle control inputs. If you know what you are doing then you should never be caught by surprise by a good auto tranny. It may not do what you would have done with a manual, but that's the nature of the beast for some edge cases. Once I scoped the rules the tranny seems to be using I could pretty much get it to do what I want 97% of the time. The other 3% is just not possible to do "automatically".

So what percent of the time do the rest of you find yourself in agreement with your trannies' choices WHILE you are actively managing its behavior with the throttle and brakes?
 
#2 ·
Considering that my SBM has a little over 7K miles, I think about 90% of the time I drive I don't experience any tranny mis-behavoir. It is well broken in. But I do agree it is how well you know the tranny that will react according to your level of driving.
 
#3 ·
I've noticed that when the car hasn't warmed up(mornings, usually) that the tranny can give some "bumpy" shifts at low speeds. Also have noticed this during stop and go traffic sometimes - it seems to shift a little more jarringly than normal. Not really sure why this is.

Overall, this happens about 5% of the time.
 
#4 ·
I am still at the tail end of my "break in" period so I haven't put the trans in "PWR" mode yet, but I do notice a delay sometimes when slowing down for a right hand turn, and then I hit the gas to merge.

I am still hoping that with traction control off and in PWR mode this will improve, but I am not going to play around until past 1K miles.
 
#5 ·
Originally posted by lowprofile:
I've noticed that when the car hasn't warmed up(mornings, usually) that the tranny can give some "bumpy" shifts at low speeds. Also have noticed this during stop and go traffic sometimes - it seems to shift a little more jarringly than normal. Not really sure why this is.

Overall, this happens about 5% of the time.
My car behaves EXACTLY like this.
 
#6 ·
sometimes at slow speeds my car feels as if it is not moving even though i am pressing the accelerator. and about 80% of the time this happens my car shifts very roughly like when u first start to drive manual. dose my car have problems or is this normal. it has 3500 miles and i always drive it in power mode

yellow is
 
#7 ·
I have noticed two things which don't seem right with my transmission:

1> Sometimes when I slow down for a corner, then jump on the gas to get going it acts (for a moment) like I didn't push the pedal at all. There is no response then it finally decides to kick in. Perhaps the "lag" is like 1/2 second or 1 second so it is not a huge delay, but noticable nonetheless.

2> On two distinct occasions (so far), I have been trying to accelerate at slow speed (like hitting the gas at 5mph) and the engine just revs like it is in neutral with no acceleration. I let off on the gas, let the revs drop back down then try again and it then goes like it is in gear.

I don't know if these problems are related, nor if they are unique to my car (although I have seen many other posts suggesting that others are seeing similar things with theirs).

Right now my car has 780miles on it, so I am still leaving it in normal trans mode (not PWR or SNOW), and I typically put the shift lever in "M" mode even though I am not really doing anything with the e-shift buttons. I know this has happened when the car is already warm. All these anomalies have happened at very low speeds when trying to accelerate. I haven't noticed anything weird with the shifting on the freeway.
 
#8 ·
Hmm..interesting. I have exactly the same symptoms on my car, though I always drive in "D" mode (not "M" mode), and it doesn't particuarly matter if the engine is warm or cold. I thought maybe it was just me, but the number of messages on the forum that descirbe my car's exact behavior is too much of a coincidence.

I am probably due for my 5000 service this week, so when I take it in I'll be sure to mention it to the dealership & see if they have any info.

Originally posted by TEG:
I have noticed two things which don't seem right with my transmission:

1> Sometimes when I slow down for a corner, then jump on the gas to get going it acts (for a moment) like I didn't push the pedal at all. There is no response then it finally decides to kick in. Perhaps the "lag" is like 1/2 second or 1 second so it is not a huge delay, but noticable nonetheless.

2> On two distinct occasions (so far), I have been trying to accelerate at slow speed (like hitting the gas at 5mph) and the engine just revs like it is in neutral with no acceleration. I let off on the gas, let the revs drop back down then try again and it then goes like it is in gear.

I don't know if these problems are related, nor if they are unique to my car (although I have seen many other posts suggesting that others are seeing similar things with theirs).

Right now my car has 780miles on it, so I am still leaving it in normal trans mode (not PWR or SNOW), and I typically put the shift lever in "M" mode even though I am not really doing anything with the e-shift buttons. I know this has happened when the car is already warm. All these anomalies have happened at very low speeds when trying to accelerate. I haven't noticed anything weird with the shifting on the freeway.


------------------
 
#9 ·
I now have 2000+ miles and my IS transmission does exactly the same thing everyone is describing.
I find the problem most pronounced when driving in rush-hour traffic at very slow speeds. I hit the gas and the car momentarily ignores it...then lurches into action.
It's not a big problem. But it's apparently a "problem" Lexus should address since we're all experiencing it.

[This message has been edited by Leader (edited October 31, 2000).]
 
#10 ·
Just got back from my 5,000 mile service. I mentioned the problem when I brought the car in. This is what the service tech wrote on my service order:

Client states transmission hesitates after letting off gas & accelerating again
----
This is a normal condition. Car will not downshift 2 gears and reaccelerate without a milisecond delay in throttle actuation.

So, it sounds like Lexus considers this "normal" operation. Since it isn't really a major problem, it probably isn't worth escalating. Unless of course, it gets worse...


Originally posted by rmbracalente:
Hmm..interesting. I have exactly the same symptoms on my car, though I always drive in "D" mode (not "M" mode), and it doesn't particuarly matter if the engine is warm or cold. I thought maybe it was just me, but the number of messages on the forum that descirbe my car's exact behavior is too much of a coincidence.

I am probably due for my 5000 service this week, so when I take it in I'll be sure to mention it to the dealership & see if they have any info.




------------------

Bob
----
2001 Graphite Gray
 
#11 ·
Mine does it too. Only have 600 miles on it. I THINK I've learned to drive it in a way the CAR prefers, since it's happening less and less often. However, as you all probably know, the car does NOT like cruising around parking lots at low speed. It wants to GO.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top