Gtidan

Just curious. My 2006 IS250 is just over a year old and has been as reliable as any car could be.................however............lately it seems the car has a mind of it's own when shifting. Sometimes it's smooth as glass and other times I can feel each one. At approx 5 mph as in slowing down and than hitting the pedal sometimes the downshift is smooth and other times it's almost violent as in harsh.

Anyone else have these symptoms? Is there any known TSBs out? New computer flash software. Does the tranny kick out fault codes that can be checked by a computer (as Mercedes does)?

Thanks for any help.........

iSuxeL

iTrader: (21)

Is this when your car is fully warmed up?? Also, the ECU probably learned your driving style. Thats what Ive heard about this car.

Gtidan

a) the car is warmed up...

b) I understand the adaptive nature of the of beast but I don't change my driving habits between stoplights...

Thanks though for repling...

iSuxeL

iTrader: (21)

NP thats all I would think. If youre really worried just bring it to the dealer and tell them, its still under warranty so dont worry.

lobuxracer

iTrader: (2)

I know exactly what you are talking about. Sometimes you take off and its smooth as glass, and other times its like a beginner in a manual with a stiff clutch. I've noticed this throughout the life of the car though. It has not got better, worse, or predictable ever. Yesterday I took off with my boss in the car and he remarked about the smoothness of the gearbox (he's a Benz E500 owner), and today I was rolling at about 3 mph and needed to accelerate so I gave it a bit of throttle - not a lot - and my neck snapped.

I feel your pain, but I suspect it's built-in and not easily altered (software flash) AND I suspect its relatively anomalous. It would never happen if it were a manual because I could directly control it. OK, if it were a metal triple plate like the HKS I had in my Supra, maybe it would be as unpredictable and irritating - no, wait - NOTHING was that irritating!

harut44

My 04' LS430 has this problem (not really but a symptom) too and the ES350 rental we had....seems like it's a lexus tranny issue...

ldc

Why would it downshift when you hit the accelerator?

kingofire

Hey welcome to my world with my 2006 ES330, they have the intermittant jerk when going from a rolling slowdown to firm acceleration. I have a friend who is a backyard mechanic and he overfilled my tranny pan by 1/2 a quart of Type IV fluid and my intermittant jerk is all but gone. He swears that overfilling it by 1/2 a quart will not hurt anything.

harut44

lets say your roll to a stop at a stop sign and you don't stop all the way and hit the accelerator a little bit the car jerks into gear...it's wierd but i've learned to control it...you have to press the accelerator a tiny bit so it can get into gear and your good to go (its kinda hard to explain).

PandaBear

iTrader: (1)

All "hard shifting" automatics have this problem, some like Honda has it even worse. My Integra literally SLAM into a gear with a big clunk and I literally have to learn how to use my gas pedal correctly to get around it. This totally defeat the purpose of auto in the first place.

I don't think overfill the ATF will help smoothing it out unless it is under filled to begin with; using an ATF that has smoother characteristic may help. On my Integra I tried using a small blender call SpecialtyFormulation and it helps a lot. On my Corolla I tried using Valvoline Maxlife and it is very nice, but when I switch to Chevron it is very rough.

For MBz, they have more speeds in their tranny and bigger engine, so the shift from one speed to the other is not as large as a small engine with fewer speed like IS250, that a wider spread between shifting. If you want that kind of quality, you need to pay for it and buy a GS or LS.

harut44

Yup, that's also what I have done. You have to learn how to use the pedal so you don't get jerked. The thing is this isn't a constant problem but it has happened and will continue to happen enough for me to notice it.

Gtidan

Well............after reading all the postings I feel better knowing at least I'm not alone......

Sounds like that's just the way it is. I can live with it but it seems a little out of place on a Lexus when their goal is to make everything work so smoothly.

Thanks for all the input...
Dan

IS350jet

I just come to a complete stop (or nearly so) and that seem to alleviate the problem.

harut44

Yup, stopping completely eliminates the problem but if not you can always just light (and i mean lightly) tap the gas pedal and the car will get into gear normally.

IronPhoenX

It happens to me usually while slowing down for a speed bump and then accelerating away from it. Also happens when I'm slowing down and speeding up while looking for a parking spot. I always use manual mode and when I'm moving slowly in those 2 instances; I keep it in 2nd gear, but I can see the computer shifts back and forth from 1st and 2nd... so that creates the jerkiness.