StpdSavant

Hello folks,

I've had my 2007 IS350 for a few months now (bought at 17k miles and put on 6k since), and while I find the car mostly fantastic, one area I find disappointing is the transmission. Basically, when I'm crawling in traffic (or, uh, not-quite-stopping at a stop sign) and coasting down at 3-5mph, then get back on the gas, it's as if the tranny is "catching" again and I get a lurch forward. I can be as light as a feather on the throttle and roll on the pedal smoothly, but the car will still lurch forward as I accelerate.

Similarly, I hear people on the fora comment about how amazingly smooth the transmission is in daily use. I find that I can still feel the shifts quite readily, even though I do not typically drive aggressively (as I understand it, as the ECU learns your driving style, it can make shifts firmer if you are aggressive?). My wife's 2004 Corolla shifts gears less perceptibly. Are others perceiving the same thing on their cars?

Gville350

iTrader: (10)

The vehicle has probably the first owner's driving style and shift points ingrained into the ECU at this point. So what I'd recommend is forcing the car to re-learn again. Disconnect the battery, let it sit for 10-15 minutes, and reconnect. Drive the car as you would on a daily basis.

I too do experience a lurch or two perhaps daily, but it's because I "confuse" the car/trans with the gas/brake/gas/braking of stop-go traffic...it's inevitable.

calvin2376

iTrader: (2)

I just bought my 2007 IS350 about 6 months ago with 56k on it, put 6k on it since then. I've also noticed lurching, almost in the exact same situations as you. When I notice it the most is when I'm slowing down from high speed, the transmission holds on to the higher gear too long and then once it finally does shift down, it lurches forward. I think this is because I drive fairly aggressively and accelerate and decelerate fairly often. So when I'm slowing from a high speed, the transmission's been trained to think that I'm going to quickly accelerate again, so it holds the higher gear to give me the RPMs when I need it. However when I actually don't accelerate and continue slowing, the transmission's shift is then jerky and lurches me forward.

I've brought this issue up to the dealer but they said after a test drive they didn't experience anything unusual and that this car doesn't get many if any transmission complaints, and they chalked it up to the car learning the driver's style.

So I think the answer to your question is this is normal and is a by-product of the system the car uses to adapt to your driving style. The same type of thing was employed on my last car, an E55, and while that was definitely smoother in general, it still produced some lurching at times. I think it's inevitable because people don't drive the same way all the time.

Gville or anyone else - by disconnecting the battery to reset the ECU, what else do you lose? I assume you also lose radio presets, seat positions, etc?

anthrax144

I think it has more to do with the gear ratios than anything else. First gear has such a low ratio that the car doesn't like to go into it unless at a complete stop. So that low speed, stop and go traffic, the tranny is fighting between 1st and 2nd gear depending on how much you push on the peddle. At least, this is my perception. I have to say though, when driving at WOT, i love how smooth the car shifts!

syzygy

Use snow mode in stop and go traffic (5-10 MPH). The car will feel amazingly smooth. Give snow mode a try.

Bichon

Been using snow mode in bumper-to-bumper traffic on my IS for years. Like syzygy says, it totally smooths out the transmission and throttle response.

NastyIS

iTrader: (1)

I get that every so often after driving pretty aggressively in power mode.

HaveBlue

Same issue here. I think it stems from two things. First, the electronic throttle is very "touchy" at low angles. The computer turns off the injectors entirely to save gas while decelerating and this causes lurching because it switches from on/off/on at low throttle angles as you want to go just a bit faster. You can easily see this effect if you put the tranny in first gear and drive very slowly. The second is that I suspect the A760 has a high stall torque converter which requires higher rpm before it starts to engage. Makes for good high acceleration but bad low accel.
I'll bet some horrible VDIM gremlins are helping make the experience even worse too.

eternal07

Snow mode is the answer!!!

Whenever I drive in City with lots of traffic, I always put "snow mode"
It will start with 2nd gear instead of hardcore 1st, so the transmission is butter smooth.

SCWB

Thanks for having this thread. I am worried and skeptical about my tranny as well (Mine is IS250 AT)

It does exactly the same thing as the Thread Starter explained, jerky at crawling speed and hunting between 1st and 2nd as well.

I found that applying throttle very smoothly and progressively does help especially when crawling in the traffic.

I think this transmission doesn't like gas-brake-gas-brake stop-n-go driving type as it will be quite jerky especially in the 2nd to 1st gear downshift.

Also, setting off from stand still on the steep incline, the clutch/Torque Convertor will slip severely then it will grab suddenly. This will make the car jerk out violently. Very hard to control the car on the steep driveway.