pngo

Hello,

I have a 2016 IS200t with 21k miles on it.
While in manual mode while I slowdown to a stop, the car will downshift from 4th to 3rd and cause a very noticeable jerk. Sometimes I feel it while dropping into 5th gear as well.
I first noticed this issue occurring while in auto mode, but this only happens occasionally. When in manual, this happens almost every time I come to a stop.

Have any of you noticed this issue? Particularly while in manual mode? I have heard that this may be due to the engine/transmission shifting harder while in manual mode, but it seems crazy to me that this amount of jerk would be allowed.

Thanks!

SSworks

I too notice this with my 8 speed 350 F sport. I can replicate the issue now with one certain intersection I have to stop up at. Cruising about 55 60 mile or soon a long run up hill to a four way, If i just take my foot off the gas and let the car slow on its own due to going up hill and was little compression there is in each gear as it down shifts on its own I feel that hard shift from 4th to 3rd about 15-20mph . I also have hard shifts randomly when its really cold in the morning, enough to actually chirp the tires once shifting from 1-2 at 3Krpm 1/4 to 1/2 throttle with the engine and trans still cold.
My car has 65K on it and actually has me thinking should I be looking at a replacement trans soon lol

E46CT

when it's cold out it probably doesn't take much to chirp tires. but the hard shifts randomly i dont know. i would be changing your fluids at those miles.

once in a while i find the 8AT to hiccup and shift weirdly but most transmissions do that on occasion. a lot is going on inside a transmission to ensure you don't feel what's going on. but sometimes the software/computer doesn't always keep up and the exact condition exists to where that is felt by the driver. think of it as a mind fart but for transmission computers and hydraulics.

you just have to worry if it starts to become something that happens regularly.

SSworks

Okay great, I dont have any luck with Auto's first auto died decided never again 15 years of various manuals(about 10 cars) then the next auto DIED again lol lol then switched back to manual one more time now my current car is auto so maybe i am just knit picking at everything.

arentz07

Mine's always been like that in manual mode, but I have an AWD with the six-speed transmission. When I drove my friend's 350 RWD, I noticed the shifts in it were a bit "firm" compared to mine. I think it has to do with two things:

1. It will lock the torque converter in manual mode.
2. If you're manually down shifting, there's a chance you're doing it at a much higher RPM than while in regular Drive. This means combined with 1., there is a bigger difference in RPM that the drivetrain is reconciling. I've noticed it doesn't always rev-match perfectly.

If it's happening in D too, then I'd be worried. For me it's always as smooth as butter in D, even if I use the paddles to engage the engine-braking mode.

pngo

So my concern is how I can nearly always replicate the issue when coming to a stop and it downshifts from 6th to 5th and 4th to 3rd. If the ECU was just glitching sometimes or whatever, I would expect the issue to occur less and more randomly.


1. Do you know if the torque converter is locked while in any gear in manual mode? Or only after 3rd gear or something like that?
2. With my issue, the downshifts are occurring automatically as I slow down. I had my buddy track my RPMs from 4th to 3rd gear and it would go from ~1k to ~1.2k. 200 rpm seems relatively small to me especially for it to cause such a noticeable jerk... do you think that is true?

itsx

Could it be the rpms you're at? I've felt the jerkiness bc it feels like there wasnt enough rpms for the gear i was in. say if i'm stopping and going from 4th to 3rd while at 15mph. Wherease if i'm downshifting at 3k i havent felt it, but if i'm downshifting to overtake i'll occasionally blip the throttle too.

pngo

When I'm coming to a stop and the jerk occurs from 4th to 3rd, my RPMs is about 1k and it goes up to about 1.2k after the downshift, so its a 200 rpm difference. Do you expect that difference could cause that much of a jerk?

JNP1227

iTrader: (1)

I have the 6 speed AWD transmission and used to have the jerk from 4th to 3rd too while coming to a stop in auto mode. I think what caused it was it would downshift in low RPM (700-800) then want to downshift and would jerk. Never happened in sport or sport + mode.

Recently I got the car tuned and it seems to be shifting much more smoothly and no more jerking downshifts from 4th to 3rd in auto.

HOMER350

I'm really curious how much of a jerk we're talking about. Has it always been like this? Would it be enough of a jerk to say cause an open glass of water to spill?

Mine will down shift harder while in manual mode pretty consistently, unless I'm timing just perfect and doing so manually.

​​​​​​Going down into 3rd automatically is definitely most defined, but It hasn't been anything I would describe as jerkiness or really anything too alarming. On a rare occasion it's a good "jerk" but only on a slope I think.
I first was a little concerned but after reading about how the torque converter locks and other members describing the same I wasn't worried about it.

Good news is I can attest to the fact that 4th to 3rd is the more-hard shift.

I just swapped trans/dif fluid recently and behaves the same before and after.

arentz07

Even in my 6-speed, the 4th-to-3rd shift is less-than-smooth in manual mode. Yet for 2nd gear, it rev-matches perfectly and downshifts smoothly.

I agree though, it depends on what you mean by "jerk". I'd never describe the shifting behavior as abrupt or rough.

pngo

I have had two friends who are really familiar with manual transmissions feel the jerk. They felt it but did say that it was odd, but completely normal to feel in a manual trans. To me, its hard to say that that sort of jerk can be compared apples to apples between a manual and automatic tranny, since the clutch engagement mechanisms are quite different.

Since the "jerk" occurs typically only when downshifting into 5th and 3rd gear, I am wondering if these two gears share a clutch plate that could be engaging weirdly. Perhaps the software or solenoid controlling that clutch plate is activating too slow or hard?

arentz07

Since you're mentioning it's those specific gears, I think we are onto something.

The six-speed is the same way. In 5th gear I've never noticed anything, but damn 5th gear is really tall... For 3rd, it's not very smooth. 4th and 2nd are just fine. I've always assumed 3rd gear had something unique going on. Of note, even my old 2015 Camry had the same thing - manually downshifting into 3rd was not as smooth as 2nd. There must be something inherent in the design of the six-speed - potentially the 8-speed, too.

pngo

Assuming gears 3 and 5 share the same clutch plate on both a 6- and 8-speed transmission, then I think this argument would hold.
I am not super familiar with the architecture of an 8-speed, but I am guessing it is the same as a 6-speed with the addition of a planetary gear to add gears 7 and 8..

pngo

Took my car to the shop. The techs didn't find it too abnormal. We test drove a different IS200t and found the same thing to happen, although milder.

With the computers hooked up, we found that the KCLV was sitting fairly low at 17.8 and assumed fuel to be the issue. I use 91 octane all the time, although it is Costco fuel. A lot of debate goes onto whether that fuel is not up-to-par with other brand names. But in any case, I'm going to switch to Chevron and run for 1000 miles and see if there is any noticeable difference in KCLV/feel of my drives to see if that fixes things up.