tw2

I thought I would start this thread to hopefully get some ideas on what to expect as "normal" with these transmissions. I have always said they have a mind of their own and their programming is a bit suspect. It might give people an idea what is normal and what isn't. It can also apply to supercharger issues as well as these seem to create some bucking around during gear shifts also. Some of my experiences:

- I have noticed that when I am going uphill or downhill that the transmission will not change up when it would normally on the flat. Uphill sure fine.. but downhill.. if I am cruising very slowly I see no reason why it would not change to the appropriate gear, manual doesn't override it, hitting down then up gear in D doesn't help, it refuses to budge until the gradient flattens out. Sometimes I will get to 4-5000rpm in 1st slowly going down the road from a stop.

- When I floor it until the speed I want, then engage cruise control, surely that would mean it should change into the highest gear (lowest rpm) for cruising. It appears it was programmed to still follow your driving style and hold gears despite you clearly indicating otherwise.

whipplem104

There are a ton of different features that the tcu and other computers have to maintain a gear when you think it should do otherwise. Going up a hill is dependent on how long you are pulling a hill and gradient etc to how long it will hold a gear. It is so that in the mountains when you have a shorter flat part or let off the throttle a bit that it is not shifting up and down through the gears. Your comment on going down hill it should not do unless you have moved the shifter where it indicates 1 instead of D. If you are in Manual mode. M then you should be able to withing reason command the gear you want. If it is not responding. Then something is wrong. Those two complaints I would suggest that you have someone look into your shifter or if you have a tcu tune something got jacked up.
Cruise will hold a gear or downshift to maintain speed while going down a hill. But if I am reading you statement correct you are saying you accelerate full throttle to your desired speed and then set cruise and let off the gas and it hangs onto low gear for a bit. I assume it shifts up after a few seconds. This may be totally normal.

whipplem104

Oh and it is 722.6 not .5. I am assuming that was a type-0

Jake528

tw2

Yes my mistake, I was thinking I must specify the 5-speed and wrote 5 instead of 6.
I definitely understand the uphill downshifts, it makes perfect sense but not refusing to move to a higher gear while moving downhill. My 2 previous 722.6 cars did the same. As soon as it flattened out they would go into 4th, no speed change.

Yes you are understanding my cruise control situation correctly. It will shift into a higher gear after a few seconds. Sometimes it will stay in 2nd for up to 10 seconds at 3000rpm. I think my car sees me as bipolar. I think I would be switching between E and S+ a lot if our cars came so equipped like the newer ones.

tw2

Forgot to mention I am definitely in D and sport mode every time. When I am in manual mode I get fast downshifts on request but upshifts are very lagging sometimes holding the gear for several seconds at 2500+ rpm.

mondo

i have noticed when i accelerate at WOT in a lower gear, then lift off, it seems to hold that gear and not change up. that's a bit annoying. also when in M and trying to shift with the paddles/butons and it just changes when it wants anyway... that is annoying too! lol...

also with mine, it is currently hunting intermittently with a slight vibration and noise evident when cruising (mostly at lower revs) as if it wants to change down but doesn't. i had another car i owned do that once but far more severe and it turned out to be the torque converter. i am having a service done in two weeks and going to have the tranny fluid checked for glycol as mine is a 2003 model and i am now paranoid after reading about the radiator issue. car only has 35k miles on it so hoping that it is not that. will be having the tranny flushed too and new fluid.

tw2

Yep I don't think they spent very long on the programming in these types of scenarios. I would prefer not to have drive style adaptations. When I first had my CLK55 it would change gear at 1500rpm, last owner clearly gave it a very easy life. No matter how I drove it, it never did that again, only excessive gear holding.

Have you changed the pilot bush too?

mondo

no, this will be the first service since i bought it. i don't drive it that much in the scheme of things.

i have considered buying a tune and transmission tune for it, but tbh find it hard to justify spending the cash. having the TCU reset is an option that might be worth exploring. that way perhaps, it can learn my driving style?

kiluminati616

here's one - you can use the buttons to change gear while in Comfort or Sport but that doesn't necessarily mean that you're in Manual. for about my first month of ownership i thought i had an issue with the transmission because i would drive in S and downshift with the buttons when i wanted to do a pull but wasnt able to upshift with the button prior to getting close to redline. the car would hold the gear and was unresponsive to me hitting the upshift button. later on i realized that you need to put the car in M in order to go full manual -- downshifting in S then dropping the hammer will result in the car staying in sportshift mode and holding the gear

tw2

ECU tune is definitely worth it. I think the only TCU tune I have read anything positive about is the RaceIQ one. Every other one didn't seem to make much of a difference. I think with every TCU tune you still have to ship the TCU to the US. As I understand it, the TCU is always learning your driving style. When you reset the throttle pedal it starts from scratch. I guess glycol test, pilot bush, gasket, filter and fluid change would be a good way to go.
Mirrors my experiences too. The car is very happy to downshift but almost refuses to upshift again when you tell it to. I believe it will change gear in C or S when hitting redline regardless, I am not sure about M mode though, I know some of the later model AMG's will bounce off the limiter, I haven't tried it.

newe55guy

Sport mode it shifts way better for my style of driving. Also I have a TCU tune too.

SICAMG

OK so here is my 3 cent's worth of nothing on these transmissions and TCU's. I will start from the beginning of ownership and go from there. I am a transmission rebuilder by trade.....so.....VERY pickey on how anything shifts.
With that being said my transmission would drag out its shifts in sport mode on any type of grade. It will never shift the same week to week but will work in manual mode in sport and M mode with no issue and have raced for years like this but shifts are to mushy for me. I originally did a Eurocharge TCU tune with very little change. I had the valve body done by IPT and only saw a firmer 3-4 shift under heavy excel. This year I thought OK lets rebuild her for next years racing and tighten up all the drum clutch clearances to smallest allowable specs and that should make a big difference....nope !!!
In the end here is what REALLY made a big change but I am not going to say where I got this TCU from so I don't get ripped on for doing it. At some point I bought a supercharger pulley from a company that had horrible belt slip. Come to find out the the belt grooves where no machined correctly and I had to fix them on a lathe ...grooves where like knife edge's and where not grabing the belt. Soooo....to make up for my hassle the company sent me one of there TCU's for free in good will. I did not need it but figured why not have a spare. So put it in for the hell of it not expecting anything and all I can say is holy sheet !!! Absolutely perfect. Shifts where instant and firm in every mode and the intire personalityof the trans changed. It worked FANTASTIC and anyone in the car was really surprised. But.....after 2 week's or so it is right back to where it was originally...almost, but still better, and has "learned" it's grandma ways all over again which I find very strange and agrevating to say the least. So very long story short...these ECU/TCU combinations are VERY smart and will always get there way for what the engineers wanted. They are what they are I guess and I gave it my best shot LOL !!!!!!

GinDistiller

Yep TCU tune helped for me too at first, but it relearns. I got it mainly to allow steering wheel buttons to shift in any mode, since my main complaint is that it shifts too early and is very hesitant to downshift when accelerating. I will be at 40% throttle and stuck at 1200rpm, it's either that or stab the gas and take off like a rocket, there's no middle ground.

So, TCU tune and now I can just tap it to downshift no matter what mode I'm in. That's my 'fix' haha.

tw2

Thanks heaps for the info. At least it makes it unlikely any of this behaviour is a mechanical issue.
I forgot about that aspect, I get the same thing. I put my foot down quite a way and I get no gear change, just acceleration from 1500rpm. A bit more to go to completely flooring it and I drop 2 gears and the rear is all over the place. No middle ground.

jvakos

Sorry wrong thread

PieRat

I have the weirdest thing happen with mine since i changed valvebody and admittedly have a Taiwanese conductor plate. I had a new mercedes conductor plate to go in but it was damaged in freight. I also had a blue top solenoid which had a slightly caved nipple from freight again but I figured it was prob fine after looking up how these solenoids work. trans seems to run fine the only issue I have is when I first start the car hot/cold if I am in C mode the first gearshift like gets stuck and then when it finally pops out of gear and into the next one it does it real hard and fast which makes the sc and serpentine belts slip it so harsh. all shifts afterwards are fine in c mode and as I said it runs mint in s and m.

as usual the maintenance list is growing with a potential rack/power steering pump replacement, a vaccum leak/shakey idle and a water leaking into boot I just cant track down lol.

do want to get in there and replace that plate and solenoid at some point hopefully gets rid of that one issue will be costly for a one off shift..

jmb614

Is the trans in sport mode? I always thought that when in sport mode, the car doesn't spend enough time holding the gear. It's quite nice to take a corner and have S mode hold gears. :-) I also like the fact that if I'm not in manual, but had been playing with the flappy buttons, C and S will shift for me when the car needs to shift, usually I bump them inadvertently.

mondo

tbh i can't remember. been a while since i have tried it. have barely driven the car for the last few months since the Rona locked us all indoors.

the issue with vibration/hunting at low revs i had seems to have gone away though which is nice. car is due a service again now. still hasn't clocked up 50k miles yet lol...

PieRat

sport mode should hold gear after lifting off during wot as this is track behavior so you can go into corners with more precision as old mate said.

good news for you mondo mate if you tap the shifters to upshift after letting off wot in sport mode you can program the learning computer in the tcu to act more like you desire after doing it a bunch of times.

PieRat

also mundo mate could be your valvebody. I had ssme issue fixed with new valvebody and solenoids coz I got a good deal on the lot. you could try replacing just the torque converter solenoid and maybe the conductor plate if not done already if you wanna try save costs. It can be costly to replace parts 1 by 1 here as the oil is like 100 bux a pop as you lose around 3litres of oil each time you drop the VB.

feeshta

Mine has been misbehaving a lot recently, as discussed in a thread I started a week or two ago.

That said, one behavior that has always been there that I dislike. That would be the tendency to hold too high of a gear too long, especially when in sport mode. Honestly, the only difference I have ever been able to tell between comfort mode and sport mode on the transmission is starting out in first gear, otherwise it feels exactly the same, so it always stays in Sport mode.

An example of the behavior I am talking about is as follows. When you exit the autobahn into my little town, there is a section of road with a 60 KPH speed limit and a slight uphill slope for about 500 meters or so. The E55 always wants to stay in 5th gear up this slope, at like 700 RPM, and chugging. I don't feel this is at all appropriate for a sport mode. A quick stab of the throttle will break this for a little while, then it will shift back up to 5th. Honestly, it should be in third gear in my opinion, as that is just below 2000 rpm at that speed up the hill.

tw2

Mine is the opposite, I am cruising around at 3000rpm all the way down a 50km/hr road. It finally goes into 3rd/4th near the end. Up and downhills are crazy on this car. Flat is the only gradient where you can almost predict how it will behave.

coupesedan

I just use S for cruising and press the clicky button when I want it to upshift mid pull

PieRat

Feehsta perhaps your torque converter is not operating correctly similar to Mondo's? If the car is bogging down under low throttle conditions it may be because the programming tells it that it can be in this gear with this speed and throttle application, but in reality your torque converter is locking up too much when it should be allowing more slip and the engine to get some more rev's? I think this can be diagnosed with star by checking line pressure?? Im not expert and hard to say! Maybe whipplem or some other transmission masta will weigh in! I suppose it depends on what sort of 'slope' your talking about too lol one mans gentle incline isz anotherz mountain lolol!