lexus-is2

I get this very strange jerk/judder on my IS250 which happens on 3rd gear. I am hoping someone might be able to help diagnose it.

When i'm moving in slow traffic and applying little throttle to slowly accelerate and keep up and maintain distance, at this point if the car shifts to 3rd gear with my foot gently on the pedal, the car would jerk back and forth unless I press down on the throttle pedal a bit more. It's not aggressively jerky but enough for me to feel.

The only way to prevent it for me is to make sure either just before it goes into 3rd, i come off the throttle completely and let the car roll into 3rd and once it's in 3rd it seems ok. The other option is before it goes into 3rd, i need to make sure i'm not so gentle with the throttle, but problem with that is then I close the gap between the car in front and me too quickly and then have to use the brakes unnecessarily.

This all started about 3 oil changes ago when I had to topup oil, i topped up with a Castrol product and after few weeks this started. But for the past 2 oil changes i've switched to Mobil 1 and when I do the oil change it seems to be better for a while and then it starts again.

The oil could be just a coincidence or might have something to do with it. I am wondering could misfire be a cause? would misfire cause this only to happen on a particular gear?

Any suggestions on what I can check?

Thanks.

FSportIS

iTrader: (13)

I had very similar symptom like you said but in between 1st to 2nd gear. It usually happens during bumper to bumper traffic or when my car is going down the street with declining slope. I recently brought that attention to my own mechanic as well as having Lexus dealership diagnose it and they even let the Master technician test drove it couple days. It turns out normal, no misfire, no code, no carbon build up, no nothing.

For a peace of mind and if you car still have warranty, bring it to the Lexus dealership for diagnosis.

MikeFoxx

iTrader: (8)

I've only experienced this when I forget to turn off the ect power button when I'm in stop and go traffic. If it's not on it never happens and when it is on it will sometimes happen if I'm right at that shift point but not needing to actually accelerate and shift into 4th cause of slow traffic.

Slackful

Any update? Ive notice this happened to my 2007 IS250 as well. Id like to address this before it gets worse. Thanks!