MikeBoyIS

Hello, since few days I'm experiencing rough shifting on my Lexus IS 250 from 2006, it has actually 205000 kilometers (125k miles), I feel like it's getting worse day after day, I'm not using the car a lot but I can definitely tell I didn't have those rough shifts before.

I did the FIRST drain and fill 10000 kilometers ago (no filter change, no dropping pan), car felt great after adding exactly the same amount I drained with MANNOL ATF WS (it was 2.6 liters)

Now every gear change 1 to 5, (6 feels great and smooth) seems like I'm driving a manual car and i'm stepping on the clutch pedal hard to do a shift, car jolts forward.

I think I can feel some kind of "treble" too when I'm cruising on the 4 or 5th gear.

When I put the car on drive or reverse, I can feel some kind of "thump", the gear shift seems delayed (but not too delayed, it happens in a full second or 2, was happening before the trans oil drain, maybe my differential is overfilled ?)

I don't have any codes on techstream, otherwise the transmission feels great, no missed shifts, no delayed shifts, car is not holding on the gear and is not slipping.

I read that on 2006 IS, the ECU can get fried and rough shifting happens, but usually between 1-2-3 gears, my problem seems to be "mechanical", the transmission acts exactly the same on S mode.

I'm asking myself if I should do another drain and fill, I read that changing the filter was kinda useless on those trans (from the car care nut video), I'm wondering if it's not the motor mounts or even the transmission mounts that are going... car is 18 years old.

Any suggestion is welcome, I want to fix that car as I love it and feel like I'm mechanically enclined to it, kinda like to work on it, did a lot of job on it.

The gear shift really is feeling rougher and rougher the more I drive the car.

2013FSport

iTrader: (2)

Was the fluid that came out burned? Black? 2.6L isn't much of a swap out. Given the time and age, I'd drop the pan and filter, look at the magnets and filter and see if they are loaded up. Then set the fill level by using the overflow procedure.

Could mounts be bad, sure but they don't typically generate harsh down shifts. I have a DIY trans fluid swap. Look it up as you can get a lot more fluid out.

MikeBoyIS

The fluid was dark, didn't smell like burned thing, more like a very old oil. I just read your guide, I don't know how much kilometers had your car before doing it but I dont know if getting rid of all the old fluid would help the transmission, the harsh shifting doesnt happen only on downshifts, it happens more on upshifts that's why I was thinking about mounts, because the car seems to wobble at each shift, doing your procedure scares me and feels like doing a bet on whether I kill my car in a few days / weeks with that new fluid, or it fixes magically everything, or trying few unexpensive fixes (like mounts) to try to fix the shifts before touching the fluid again, but I might at least first check the fluid level

dwoods801

It sounds like you could have a bad motor mount or bad torque strut, maybe even a bad cv axle. I can’t picture anything internal problem with an automatic transmission that would cause vibration like you described. Have you done a visual inspection of the underside of your vehicle? Look for any obvious problems like grease or oil splattered anywhere? A symptom of a bad bearing. You can diagnose a bad motor or trans mount by watching the engine for lots of flex, while someone puts it in reverse and then brakes hard while revving the engine. Usually hear some clunky noises, and it will be pretty clear that it’s not mounted solid anymore.

MikeBoyIS

I'll check that thanks


Here is the engine mount test, I can tell the car really didn't like the test (I did the same test some months ago and didn't notice the engine moving like that), I think the engine moves a lot, what are your thoughts ?

EDIT : checked the video again and it seems that the engine moves a lot more upwards on the right side (when looking the car in front of you), I remember after doing that the car really didn't like going to reverse as I heard a louder thump, but got away after.


And here is the transmission mount test, the mount looks kinda toasted on a video, might check it from closer later (the car is low and didn't have time to put it on jack stands), you can see the lever selector (?) move on the right of the mount, the drive-line kinda move at each shift and you can hear some thump, I did hear my first grinding noises while doing those tests but it seems like its the exhaust pipes grinding on the metal plates above.


Kinda scared to keep driving the car as everything seems to move, don't wanna damage all the drive-line with those wobbles