additive

I seem to have a very strange issue in that I experience a hard downshift in C (Comfort) mode when coming to a slow stop. It only occurs upon first startup on the car and then once it is warmed up, then the issue does not happen. So, by the time I get to the dealer, I am unable to reproduce the issue and the diagnostics scans do not pickup any codes. I did have them update the car to the latest software and it did not change the behavior.

A lot of people have posted that that is happens to them in Sport mode. But I am unable to reproduce the issue when I am in S (sport) mode. It does seem that it would have a hard downshift in C mode. The fluid has been flushed as of couple of months ago.

I am not too worried about it given all the complaints of the 722.9 in the forum. Just thought I would throw it out there to see if anyone has dealt with the same issue. The car is a 2004 S500 RWD. 106,000 miles on it.

Would the rear transmission mount have anything to do with it? I haven't changed it out yet.

Welwynnick

First thing is to check the oil level.

Transmission mount fail would have other symptoms.

Nick

tusabes

Leave it in sport mode

additive

Thanks for the replies and suggestions. I see no issue with leaving it in sport mode.

As far as checking the fluid level - kind of a pain to do with the 722.9 in that it does not have a dipstick tube. I changed the fluid myself and ran the transmission up to temperature, pumped it full and then let it drain until it was just dripping before putting the plug in. Maybe I will try adding 1/3 of a quart next time the car is up on jacks.

Fried Chicken

My 722.9 HATES the cold.

I think it's safe to just let it warm up and you'll be ok.

Whoever decided removing the dipstick was a good idea should be shot at dawn. **** everything about this. It makes me MAD. It's not a simple omission of a dipstick tube. It's a combination of hubris, greed, and arrogance. And then they find out they messed up. It's like when a parent confiscates one of your toys and then loses it. The anger. KILL.

cybertronicify

I have come across this really good additive. Zmax. It's basically mineral oil based on the MSDS, but I poured that in the Gas tank Engine oil and Transmission oil. The car runs like a dream, it doesn't vibrate when idle at all. Feels like the engine is not on. Almost as smooth as the M120 V12. Transmission shifts are smoother based on a few people's opinion. I did 12oz in Gas tank, 12Oz in engine oil. 8Oz in transmission.

I used the Car Dealer Formula, the normal colored versions should be the same stuff.

tn52

Hi everyone:
It's about 32F-34F in Dallas today and I experience exactly the same hard downshift coming to a stop. I have a 2006 S500 with 7 speed transmission (I believe?) and I drive with Comfort mode. I do notice that the issue disappears when the car is warm after 20-30 miles. This is my first time that I experience the problem after many years of transmission free issues. I did a search and found this thread that correctly described my problem. The car have 58,xxx miles so I hope that a transmission fluid change is not required yet. So:
1. Is there any new resolution other than what have been suggested here?
2. What could possible broke or be the cause after so many years of excellent transmission operation?
Thanks!
tnn

additive

I have around 106,000 on my 04 S500 RWD. My transmission fluid was changed at ~102,000 miles on it. I don't know if the issue existed prior to changing the fluid since it is my wife who drives the car. I bought the car with about 101,000 miles on it, so I don't have much history with the car.

I might add that I noticed the same issue in Sport mode, now that I am looking closer at it. I might have said this before, I did mention it to the service department at the dealership when I had the car in. They did a diagnostic on the car, updated everything to the latest software and the issue still exists. If I want them to be able to experience the issue, I will need to leave the car overnight with them, so they can test drive when cold.

Given all the issues that I have read about the transmission and lack of clear root cause, I am choosing just to live with it. If had paid full price for the car and it was under warranty, then I would have a whole different attitude.

If the service department at the dealership had some suggestions, I might listen to them, but when they have nothing to offer as having seen the issue before, I am very hesitant to have them start guessing. Since no error codes were found, they don't have anything to offer.

roger1409

I have 06 s430 with 7 speed transmission I had similar problems with mine
in fact I hated my car for the same reasons. But when I changed my motor
and transmission mounts my problems went away and now I love my car
again. To me I think that the rubber on the motor mounts when cold causes
your problem, all I know is that when I changed them my car runs the same weather it is cold or not and that has been good for me.

additive

Thank you very much for the information. I will put the mounts on my long list of to dos. Happy new year.

Fried Chicken

I changed the engine and transmission mounts; the problem persisted. I'm extremely hesitant to put an additive in my transmission fluid.

doni01

iTrader: (1)

Don't think the Mounts have anything to do with the shifting. More likely vibration

Russell Ormerod

Firstly if you checked your oil level at operating temp then there is too little oil in the box. Secondly have a look at adaption values for downshift and re adapt to see if the shift improves

additive

Thank you Russell Ormerod, it appears that you were right on the money. After living with this for past almost year, I finally did the procedure to clear the transmission learning (turn key on, press on gas for 10 seconds, turn key off, let off gas and wait for 2 mins before starting, then drive for 15 mins.

After doing it in the evening, this morning it did not exhibit the harsh downshift. So, I will give an update if it was a false positive today, but looking promising.