gadgetman1

Has anyone noticed a transmission (I think) flutter around 40 mph without load? I’ve had vehicles that had a transmission flutter when the torque converter was about to engage between 40 & 50 mpg. This feels just like that. It’s not really alarming, but it doesn’t do it all the time, so it’s unnerving. The reason I think it’s the transmission is when I switch to Sport mode, the tach doesn’t fluctuate at all. If it did, that would be the engine.

I’ve also noticed the engine sometimes will begin to shut down, stumble a little & then continue to run. The way the driveline is set up, makes it very difficult to pinpoint what is going on. Anyone else notice these issues?

ukrkoz

Interesting. I am not sure what you mean by flutter but..
How about this for comparison. I am hunting down cause of shake in my Highlander hybrid. ROLLING between 25 and 40mph, that is when ICE is TURNED OFF, I have a very noticeable back-fore jerking. It feels like what you describe - like as if clutch is slipping. Except that we have no clutch or TQ. Slightest touch to accelerator pedal, brakes or simply tossing gear shifter into N immediately stops that that shake.
I am in route of replacing all engine mounts (94 000 miles) hoping this will fix it. otherwise, there is no telling why it does this, as engine is NOT running.
I have theory though. Mine is AWD. I am suspicious that at those rolling speeds, front and rear wheels somehow do not quite roll at the same RPMs, causing that back-fore jerking. There is nothing else that possibly can do something like this on hybrids.

gadgetman1

Maybe a better description is oscillation or vibration. It’s light, but both front seats can feel it. It’s not really like a tire out of balance, it’s much more subtle than that.

IrishJoe

I also feel the vibration at about 40 mph during the first few minutes of some drives. This does not always happen — perhaps 20% of the time. Like gadgetman1, I put it in Sport mode to see if the vibration showed on the tachometer — it did not. It is annoying when it happens because the 450h is usually so quiet and smooth. I’m planning to have my dealership’s service manager check it out.

ukrkoz

OK, let's get more specific.
Vibration - up down or back fore? I can tell. It feels like slipping clutch or clutches in automatic. Car wants to go forward, slows, forward, slows. except that it is rather rapid vibration.
Also, try doing what I did - put gear shifter into N and check if it goes away. Don't be afraid, nothing will happen bad. As you feel it in seats and I feel mine more with left leg and floor, I am more suspicious you have out of round or balance tire. Have no doubt your car was recently balanced but my experience is - ONLY sticky weights stay on alloy rims. Clip ons fall off alloy.

ggebhardt

Around 40 mph is where the EV gets a forced shut down and it goes to gas engine. Every once in a while you can feel the change but I would not call it a flutter. It is just how the hybrid system works. Sometimes it depends on if increasing or decreasing speed. I will take the CVT any day compared to the RX350 tranny that can not decide what gear to be in.

ukrkoz

No, I am talking continuous vibration that can not be contributed to ICE on-off. I know that shut down very well, after closing on 8 years and 2 hybrids. It's something different. Hell of annoying though. Good cars, spoils drive badly.

ggebhardt

well neither of my 450h units do,this or I do not notice. Both of them are silky smooth to me. Such an improvement over my 2016 RX350!

ukrkoz

Glad for you but does not help me. Mine was silky smooth also, that's why I like hybrids - no shifting points. But somewhere around 80 000 miles it started being more and more noticeable. Like I said, hell of annoying. And to make things worse, exactly when you get best mpg - rolling with ICE turned off. So you either have to shift into neutral, or accelerate or touch brakes. On a regular car I'd have diagnosed it long ago but here, because ICE turns off, it's a guesswork.

gadgetman1

ICE = ?? Is this an acronym for something in the hybrid system? What are you turning off when you say “...rolling with ICE turned off...”?

riredale

Internal Combustion Engine

gadgetman1

Oh, duh! I have never heard anyone refer to it like that. Thanks!

gadgetman1

40 mph your electric motors stop? Mine quit way before 40. I have experimented with how far & fast I can go in EV mode - maybe 25-30 mph tops. I have noticed the electric motors will kick off & on at highway speeds or from a dead stop or going up a steep hill. It’s extremely seamless & the only way I knew they were working was watching the battery meter that tells me what system I’m running on.

This fluttering feeling doesn’t have a sound to it & only occurs at certain conditions, so it doesn’t happen all the time.

ggebhardt

I can with a light foot, stay in the electric mode until around 40mph is reached. At that point the gas motor kicks in.

ukrkoz

MG had cut off RPMs equivalent to 42 mpg on level surface, slightly higher on downhill, but it was still designed to turn ICE at 42 mph.
Then they raised it to 45 mph on new models. New models have more powerful MG - motor generator - that can spin to higher rpms without overheating. It was somewhere around 3200 rpm for older ones.
I can take off and get all the way to cut off speed in electric mode. On a level backroad. It's painful but doable. I have good foot.
But let's not to hijack the thread. I am most interested in it as, like I said - this shake is very annoying.
I plan on replacing 3 engine mounts left, I already did pass side one. So I'll do dogbone, front and drive side ones. I'll report back.
If it didn't help, I'll replace driveaxle on driver side as it clearly feels from about that area. If that didn't help, it's inside PSD - power split device, likely one of MGs acting up, so I'll sell the car. i can't keep driving with that shake. Irritates heck out of me.