Is250 - Starting From A Dead Stop

[Race Condition]

Hi folks,

I'm encountering a performance oddity. I have an 07 RWD IS250, automatic, and I'm noticing that the engine lurches when I accelerate from a stop. It's something I would expect from a manual transmission, but not a luxury automatic.

I can mitigate the issue by being extremely gentle with the gas pedal, but I'm surprised that I should need to. My automatic Corolla didn't have this issue, but my manual Neon did (back in the day). At the time I chalked it up to the Neon being a crappy car.

Is this a common thing? Is it just something with the transmission? Note, I run without the ECT - no "power" and definitely no "snow" mode. The car only has 500 miles on it so I'm still babying it for the "break in" period.

Thanks in advance. :)

[firerock]

I think when I first got the car I experience the same thing. Now come to think of it, the problem kind of goes away. Maybe it's a break-in thing?

[Chip Monk]

Hi folks,

I'm encountering a performance oddity. I have an 07 RWD IS250, automatic, and I'm noticing that the engine lurches when I accelerate from a stop. It's something I would expect from a manual transmission, but not a luxury automatic.

I can mitigate the issue by being extremely gentle with the gas pedal, but I'm surprised that I should need to. My automatic Corolla didn't have this issue, but my manual Neon did (back in the day). At the time I chalked it up to the Neon being a crappy car.

Is this a common thing? Is it just something with the transmission? Note, I run without the ECT - no "power" and definitely no "snow" mode. The car only has 500 miles on it so I'm still babying it for the "break in" period.

Thanks in advance. :)

Mine does too. It doesn't in pwr mode, though. 4000 miles on it. Hope it's a problem that goes away. Love everything else about the car.

[clay1]

Hi folks,

I'm encountering a performance oddity. I have an 07 RWD IS250, automatic, and I'm noticing that the engine lurches when I accelerate from a stop. It's something I would expect from a manual transmission, but not a luxury automatic.

I can mitigate the issue by being extremely gentle with the gas pedal, but I'm surprised that I should need to. My automatic Corolla didn't have this issue, but my manual Neon did (back in the day). At the time I chalked it up to the Neon being a crappy car.

Is this a common thing? Is it just something with the transmission? Note, I run without the ECT - no "power" and definitely no "snow" mode. The car only has 500 miles on it so I'm still babying it for the "break in" period.

Thanks in advance. :)

Exact same problem. I called in "Choppy Tranny" in an earlier post but got no replies - I do not expect it to go away. I expect to live with it. THe only way to avod the choppiness is to use the pattles.

[bartkat]

If it only does this when taking off from a stop, it could be a delay in the pedal/throttle action. Not sure how to fix this on the 2nd gen IS, but the dealer should know.

[CrunchySkippy]

I experience something similar, but I think it only occurs to me when I'm rolling (very slowly, think of a rolling stop). I always thought it was "stuttering" between the downshift of 2nd gear to 1st gear. Sort of that in-between stage where the transmission believes it could accelerate in 2nd for a split second before deciding to drop down to 1st.

I can't say I've ever paid enough attention to the gear indicator when this happens. It is quite infrequent for me (but still annoys me). It seems to have a positive correlation with how hard I accelerate during these situations (i.e. getting out of a sticky situation).

I see how the paddles/manual mode would help here. However, I think I can count on one hand how many times I've used that function...so I'm likely to upshift when I want to downshift!

[Race Condition]

And I'm actually a little afraid of using the manual mode, because I'm still breaking it in and the "gear indicator" display mode shows that the automatic's already in 5th gear at 30mph.

If I get adventurous I'll try it out and see if it changes anything.

[Race Condition]

In ECT power mode, the problem all but disappears. I wonder if they had to make the normal transmission a little "looser" so they could get more mpg or whatever out of it.

[jrobsea]

I think when I first got the car I experience the same thing. Now come to think of it, the problem kind of goes away. Maybe it's a break-in thing?

I think this might be a matter of breaking in the driver rather than breaking in the car. I noticed the car is pretty jumpy starting up from a full stop when I first test drove it. Now I'm used to it. The Lexus feels normal, but when I drive my other car (Toyota Sienna), it feels like nothing happens when I step on the gas.

I always figured this was intentional by Lexus to make the car feel more powerful and responsive.

[dptiger]

I have the same issue, but when I took it to the dealer, the technician explained me that this is due to the new technology called "wire by throttle", which means that the computer in your car determines the amount of gas needed instead of the old system where it was controlled by the cable going from your paddle to the fuel system. It is supposed to learn your driving habbit (pressure you put on your gas paddle) and learn over time and you will feel less and less of that hesitation or whatever feeling you are experiencing.

[dojoman74]

I have the same issue, but when I took it to the dealer, the technician explained me that this is due to the new technology called "wire by throttle", which means that the computer in your car determines the amount of gas needed instead of the old system where it was controlled by the cable going from your paddle to the fuel system. It is supposed to learn your driving habbit (pressure you put on your gas paddle) and learn over time and you will feel less and less of that hesitation or whatever feeling you are experiencing.

Yep. What he said is correct. My local Lexus tech confirm it's computer controlled instead of wire, though I didn't know about the learning from driver's habit. When I first got my IS this was the annoying thing about it. The car didn't want to go when hitting gas and takes off jerky.

[clay1]

I have the same issue, but when I took it to the dealer, the technician explained me that this is due to the new technology called "wire by throttle", which means that the computer in your car determines the amount of gas needed instead of the old system where it was controlled by the cable going from your paddle to the fuel system. It is supposed to learn your driving habbit (pressure you put on your gas paddle) and learn over time and you will feel less and less of that hesitation or whatever feeling you are experiencing.

Yes I heard that too and think it is total crap. my earlier post says it all..."Choppy Tranny". The car (and/or me) hasn't learned a deamn thing in 10,000 miles in four months