Hey guys, 2009 GS 350 AWD here with about 122k miles. When cold, it'll shudder under very light acceleration (1,500-2,000 rpm gear changes) around 25 mph and again around 35-40 mph. Goes away instantly when either letting off the gas or stepping on it harder. The transmission seems to function fine otherwise and as a matter of fact, the issue will vanish *almost* entirely after driving for 15 minutes or so.

I did a drain and fill less than 2 weeks ago, replaced about 3-3.5 quarts of fluid (used Toyota WS ATF). I figured it is worth noting that the fluid was pretty brown when it drained out; didn't have that nice cherry red ATF color anymore which was a little concerning.

After the fluid change, I noticed a SLIGHT improvement but still not to my liking.

After some searching online, this seems to be a fairly common issue. What's everyone's solution for this? I think I might repeat the drain and fill process 2 more times (with a few thousand miles in between each) and change the filter on the 3rd try. Thoughts? I figured a full blown flush at this age and mileage might be risky considering the age and mileage. I'll add that I bought the car with 109k miles and have no clue about any transmission service history.

 

I have an 08 awd with 200k miles and mine does not shutter, maybe you need to do a couple more fluid changes if you noticed dark fluids coming out. Also did you replace the front and rear differential fluids? Im wondering maybe your shutter is coming from the front diff, as it uses clutch packs to transition the power. So if the fluid is super dirty or empty it may shutter the front end.

Does it happen while in a turn?

 

That's an interesting point, no I haven't touched either diff in the car yet.

I don't THINK the shudder is coming from the front end (just feels like the whole car honestly) but I'll do a few more passes on a smooth road to double check.

And turning doesn't affect the shudder; it occurs both when turning and driving straight.

I'll change the transmission fluid again too, regardless of the shuddering culprit just by considering the color it was in. How long do you think I should wait in between fluid changes for the new stuff to properly blend in? 1,000 miles enough?

By the way, with 200k miles has your transmission had any work done to it at all? If so, what kind?

 

No transmission work only 3-4 fluid swaps, these transmission are over built, they are close to the ones used in the tundras. When it shutters do you get any lights on the dash pop up?

Try the fluid swap and do the front and rear diffs and see if that helps

 

That's good to know! And no, no warning lights whatsoever. The shuddering doesn't last more than 1-2 seconds if/when it does occur and the car is completely normal otherwise.

 

Have been driving my 2007GS AWD with the same issue for the past two years. There is a thread GS2007 shudder.
It doesn't bother me anymore. Other than that, the car is still a muscle machine at 168K miles.

 

That's good to know that it's still working. Did you ever do a fluid service? I read lots of sources online indicating that dirty/worn out fluid can cause these issues so I plan on doing another drain and fill soon.

 

No, I didn't drain & fill the tranny fluid as ibidu1 suggested. The issue does not happen every time though.
Lexus tech test drove the car back then. Guess what he spent like an hour driving and nothing happened.

I read this article:
Torque Converter Shudder Problems (itstillruns.com).
I did their diagnosis, it looks like a tranny issue.

 

You might be under filled. There’s an intricate procedure to checking the transmission fluid level.

 

That was my initial thought however after changing the fluid for the first time about 3 weeks ago, I'm willing to bet that it's shuddering from dirty fluid. It was a nasty brown color and pretty smelly.

When topping it off, I did that special procedure you mentioned where you had to verify if the trans was up to temp by putting the car in diagnostic mode. Fluid level seems good. I'm going to change it out a couple more times and see what happens.

 

So in case anyone is wondering, I changed the fluid for a second time this past Friday (about 3 quarts came out) and put about 80 miles on the car since then. The shudder is still present but I have noticed an improvement. I think we're moving in the right direction!

I'll put a few hundred more miles on it and do it again.

 

Keep us posted. Thanks.

 

A few things.

Have you changed fluid in the Front AWD Transaxle? Also a ignition miss can feel like the Trans but not be. What's the plugs, coils, air filter, condition age? The Coils sometime throw a CEL, but sometimes not, and/or take a long time to code. Have you done a intake cleaning Seafoam, or STP spray in cleaning.

The shudder may, or may not be the trans. Even feeling it on shifts it could be the Engine RPM where it occuring not the Trans shifts. Its especially suspect that its not doing it on hard acceleration. Most time but not always if its directly trans related it's going to do it at all shifts.

Also look up into how to drain and drop the pan and replace the Trans filter also.

 

I haven't changed the front diff fluid, someone else suggested that to me as well so that will be on my to-do list.

As for the other stuff, I replaced the engine air filter and all 6 spark plugs a few months ago so they're fresh. I'm not sure how old the ignition coils are, but they appeared to be in good shape when I did the plugs and the car isn't throwing any codes, as a matter of fact it passed an emissions test with flying colors back in September.

As for the intake cleaning, I actually have an oil changing coming up in about 500 miles and I plan on running a seafoam treatment through the intake AND crankcase right before that so we'll see if that helps.

I'm still fairly convinced it's the transmission because I have noticed an improvement after the second ATF drain/fill, and I researched the issue online extensively. It appears that Aisin transmissions are notorious for this issue if their fluid is neglected, and believe me, mine was definitely was; it was brown and stinky. I also noticed this issue seems to be fairly prominent in the FJ Cruiser community and their transmissions are similar to ours; and most of the time it appears that full fluid flushes cure the issue.

Plus, this issue consistently only appears right before the 3-4 and 4-5 shift under light throttle, so I doubt that a misfire would be so consistent.

For the third drain and fill, I intend on changing the transmission filter and cleaning the magnets too. The only problem I'm running into is that it appears that most online stores only carry filters for RWD cars rather than AWD. Hopefully I don't have to resort to the Lexus dealer for the trans filter.

PS if anyone has a link available to a write up on how to change the filter, I'd greatly appreciate it. It seems relatively straightforward but that's something I'd definitely like to review before diving in myself.

 

Hiya,

I have this same issue with my '09 GS350 AWD. I bought it with 79K miles and changed the transmission fluid myself soon after I noticed the shudder and noticed an improvement in severity. It still happens about 80% of the time when I drive, but it doesn't happen as violently nor as often.

I suspect the filter because for me, the first 15mins of driving, it doesn't happen. After 15mins and car is all warmed up, it begins to happen. I'm thinking, maybe when the fluid is warmed up, the filter begins to be clogged with whatever is in the pan because after that first 15 minutes, shifting is nowhere near as smooth as when I drive it after warming up at idle, or when I let the car sit for a bit and then drive. I have parts for a transmission filter and pan swap (my pan is rusted a bit and the overfill bolt is stripped to the point where I cant get it off). I'm not sure when I'll do the swap though.


EDIT: for clarity, my issue matches your description EXACTLY, except for when it happens. Mine does it after the car is warmed up and I've been driving for about 15mins.

UPDATE 9-1-22: Changing the transmission fluid multiple times fixed it.