Soon after changing ATF as in my last post shifting irregularities returned. Sucked a quart of ATF out of the filler tube and replaced with Lucas ATF additive. Problem solved. Up and down shifting very smooth and regular. Hey it works. There's no downside so try it.
Don't put crap like that anywhere near your Benz transmission. The Benz transmission has many requirements as mandated by MB for the long life & proper performance of the unit. The oil industry & the additive companies spend millions developing & testing the correct fluid to meet all requirements. Benz tests & approves the fluid.
Then somebody pours a can of mouse milk into the mix & screws up the entire formulation. The long term downside could be considerable & change seal swell chracteristic & frictional properties leading to clutch pack failure. Many other influences are also possible.
Don't do it. If a vehicle was under warranty it would invalidate it.
Use only Benz approved fluids meeting 236.14 or if you have a new 722.9 Plus transmission that does not apply to W203 vehicles then use the new blue 236.15 fluid.
[QUOTE=Glyn M Ruck;5522133]+1^ on level. An ECU reset does not reset the TCU.
Transmission adaptions can only be reset with Star (I'm not talking about learning)
The fact that it does it in both C & S makes it unlikely that a clutch pack is slipping. More likely a slight valve leak in the valve body. Did you break open your old transmission filter & look for wear material?
What happens when you select Drive from Park or Neutral? There is some delay on these cars but then it should lock up
Hello my car have a problem like this. Delayed engagement when it came from neutral, park and reverse.
Okay, battery replaced several weeks ago ... had a dead cell in it, low voltage. The electrical system feels a bit better, I can start the car with the radio remaining running now -- but doesn't affect the TC lockup/release issue.
Next steps: (1) check out the alternator to make sure it isn't dragging the engine down (although it wouldn't be applicable to the lockup delay), and (2) STAR diagnosis.
I just priced out the diagnosis from a very competent sounding indy at one hour labor ($110), and they feel they can very definitely determine if the problem is in the solenoid, valve or conductor plate.
However this is one of those toys that I think would be fun to try on my own. There are plenty of Star C3/C4/C5 units for sale out there ... I've seen the C5 listed for close to $400. If anyone out there has a unit that they wouldn't mind loaning or renting to me, please let me know.
jkowtko, its most likely your conductor plate, the best way to check it to look in the passenger side foot rest, pull back the carpet and you will see trans fluid, which is leaking from the connectore, its about 150 to buy and you can do it your self if you are inclined to do so and also take out the tcu and see if fliud got in it and spray with maf cleaner and put back in.
jkowtko, its most likely your conductor plate, the best way to check it to look in the passenger side foot rest, pull back the carpet and you will see trans fluid, which is leaking from the connector, its about 150 to buy and you can do it your self if you are inclined to do so and also take out the tcu and see if fliud got in it and spray with maf cleaner and put back in.
My connector has been replaced twice -- once early on when it started to leak prematurely, and again last year when I did my fluid/filter service. The transmission housing and electrical cord are completely dry -- there is no fluid anywhere near the passenger compartment.
If it were fluid leakage into the conductor plate, is that generally due to a leak in the connector?
In any case I am starting my quest to purchase a STAR system so I can do a full diagnostic on the transmission myself.
Very surprisingly, after replacing the front motor mounts it seems like most if not all of my transmission woes have disappeared!
* TCC late release when coming to a stop and dragging down the rpms (engine warm)
* TCC slip from stop sign after coming to a stop from 3rd/4th gear (engine dead cold)
* erratic 1-2-3 shifting when dead cold and light on the throttle (leaving the house slowly down neighborhood streets)
It is very surprising to me that the two would be related. The ECM must be very sensitive to excessive engine movement and/or vibration. But I am very happy if this is the problem vs a transmission valve body issue.
There were additional issues such as a downshift "clunk" as if something in the drivetrain were a bit loose, and a momentary lapse when I stepped on the gas after decelerating. Those seem to be gone as well. And downshifts are hardly noticable now.
And, not related to transmission, but the momentary "rumble" when I start or stop the engine, also gone. And the engine sounds much quieter from inside the car.
What you are describing very accurately matches some of the things I'm experiencing with the transmission in my '06 c280. When I purchased it I was having hard shifts, notice the clunky when not coming to a complete stop for a few seconds in 1st, etc.
I did the transmission service which fixed the overall rough shifting, but it is still grabby/clunky when almost coming to a complete stop and lightly touching the accelerator. I also experience the thuds when braking from the downshifting... I actually explained to my dealer that I thought it could be loose motor mounts or at least the problem when rolling through a stop felt like that. They thought I was crazy and proceeded with the transmission service.
Now that you've described all these issues disappearing after replacing the motor mounts I'm inclined to have them check into that again.
Do you mind disclosing roughly how much it cost you to replace the motor mounts? Are all the symptoms still gone?
I did the work myself, so the cost of Corteco mounts ($90 + 90 + 40) was all that I paid.
Of course I also have a pair of ramps ($50) and a floor jack ($80) and a few hundred dollars in Craftsman tools. And I bought the $15 offset wrench needed to get to the top bolt on the drivers side mount.
After a week or so, the symptoms are all either mostly or completely gone. I still notice a bit of erratic shifting when the car is stone cold in the morning, but it's not as bad as it was before. The TCC lockup/release issue at the first two stops when cold, I haven't really noticed that anymore. The car is very quiet on the freeway, and I usually cannot hear or feel the engine when stopped at a red light (still in gear).
So I won't guarantee that it will remove ALL of your symptoms, but it made a huge difference for me.
When I replaced my engine mounts I noticed similar behavior. My car was not experiencing any of these issues other than slight vibration when completely stopped. Apart from not feeling the engine vibrations anymore, the other subtle difference was how the car shifts gears now. It changed the behavior of how it downshifts. It's subtle but I could see the difference. The tolerances on these cars are very precise, when something wears it shows up in manners not showed in other cars. It's the sum of the whole package. Check motor mounts if you get clunk noises when the car downshifts.
I think I may have to check my mounts as well. I have an appointment tomorrow at my local MB dealer to check the transmission. During fluid change, there was no metal in the pan. When I took apart the drivers side footwell, I noticed the TCU had some fluid on the wires. I cleaned it up, did the adaptive reset on the car and went to bed. I woke up, and she shifted like never before. I swore I was driving a new car that morning, but as the day progressed and into the week, it went back to the same. I cleaned it up again, this time with electrical cleaner, but it seemed to have been a one time trick.
I'm thinking either mounts or the bushing. Checked it during the fluid change, seemed OK. Who knows....
Fluid - You should clearly be able to tell if the electrical bushing is leaking fluid. You'll have to get under the car and remove that little aluminum shield though (one screw I think).
Shifting - the word from other threads on this forum is that the first 40 starts from a standstill after a reset determine the program for the transmission and throttle body. So if you want the car to shift sportier, drive more sportily for the first few days after the reset.
Replacing motor mounts should give you a consistent improvement.
Not that this has anything to do with the problem, but I was always told to warm up my car before driving. Especially on cold mornings. I usually wait for a few minutes until it gets to temp.
Does it make that much difference?
I'm sure that would make a difference on a lot of these cold temp issues. I wait a few seconds for the oil start circulating -- you can hear that pretty clearly -- and then It will take me a few more seconds to get ready to back out of the driveway, but I usually don't wait for anything to warm up. On the rare occurence when I do let the engine idle for a while (i.e. have to run back into the house to grab something I forgot), I think it is better.
I am in the SF Bay Area, doesn't get much below 50 here, so I'm not in the habit of letting the car warm up.
Changing out the motor mounts seemed to help this situation a lot ... I don't really notice it anymore.
Bumping this because for what it is worth this weekend my dealer did a software update on the TCU and this issue has completely disappeared. I tried to replicate the issue with techs in the car numerous times in the past but never got anywhere.
I brought it in for new struts and complained about a new problem I was having with a weird delay when shifting from 2-3. When I got the car back they told me they experienced "harsh shifting" and updated the TCU and cleared adaptations. They told me it will shift differently for a while while it readapts, and it does, the shifts are harder (in a good way I believe) and the problem when almost coming to a stop and going back to the accelerator in 1st is gone, so is the delay/jerking when slowing down to make a turn and then hitting the accelerator half way through the turn. My dealer did the update at no cost to me.
Thanks for the heads up on TCU reprogramming ... I'm looking into it now. We have a stealership nearby as well as a couple of good German indies.
I'm itching to pull the valve body on my tranny, replace the conductor plate and check out the solenoids and valves. But if a reprogramming solves the problem, all the better.
FYi, I also spoke to a Sonnax distributor who has a store in the area (San Jose), and in addition to Sonnax parts they quoted me $600 for a full valve body rebuild. So I have a backup plan in case valve wear is going to be my problem over time.
So, upon more driving tonight I realized it didn't really "fix" the issue with first gear... it just does not downshift to first unless I come to a complete stop. When I'm still rolling a few MPH when I go back to the accelerator I'm still in second. This is actually more what I would expect the transmission to do though, once you have some movement you don't really need first. If I really hit the gas it does put me in first but I feel that delay again though not quite as bad.
I almost think the issue with first is just the way these cars behave. When I was talking to my Service Advisor she mentioned there are quite a few things that drivers report as issues that are really just normal.
They gave me a 2015 C250 Coupe as a loaner and low and behold it did the same sort of stuff that I consider bad behavior. In a way it was nice to know that I'm not crazy and these issues are just the way these cars are, but it seems that with different software it can behave different in the stop-go-stop-go type situations.
I think I did read your whole history with the problem and I'm glad you finally found out the solution to your issue. So correct me if I have misunderstood your issue. The car used to have rpm drop when coming to a full stop in low speeds like 10 - 30 km/h and when coming to a full stop from speeds higher than 50 km/h rpm used to be more stable and this drop was heavier when the engine was hot.
If this is the issue we're on the same boat. My car is a W203 M271.946 engine with 722.6 transmission and my workaround (but not very satisfied with the fix) was replacing the ECU with a new one and change idle rpm from 600 rpm to 750 rpm with gear engaged, otherwise having the car working for around one hour full operational temperature would cause the engine to go off in certain circumstances. I did the ECU replacement because the old one (older revision number) couldn't accept rpm increase. Also I changed the engine mountings but it just made the vibrations when coming to a full stop feel less and not fix the problem. I have the transmission connector to get changed by the end of this or next week and I wonder if flushing and checking the transmission entirely would be any solution to a final fix. Regarding STAR diagnosis I've made it several times, also full transmission shifting adaptions and learnings but those actions were no solution to the problem.
I would appreciate your experience in order to guide me to a definite fix.
Thank you in advance!
Well, I haven't solved my problem yet 100%, but in the process have done both short and long term maintenance that is no doubt beneficial to the car.
What I have done that may be relevant to this issue:
* tranny fluid flush, filter, and electrical adapter plug
* motor and transmission mounts
* removed and cleaned throttle body. There is still a chance that the throttle body is just old and not as responsive as before, which means replacing it with a new one. I would do this immediately if they weren't so pricey.
* replaced engine air intake temp sensor, located just behind the throttle body. I think this affects the mixture richness from the ECU's perspective ... if it's reporting cold air when the engine has warmed up, maybe the fuel mixture is being set wrong?
* defective "$12 vacuum hose" under the air filter box, replaced under warranty a long time ago. I seem to remember the engine stalling as one of the symptoms here.
* new spark plugs
* new engine air filter, or make sure current one is clean.
What I have not done yet that may be relevant:
* I keep forgetting that this transmission has a "Comfort" mode which starts in 2nd gear. I need to try running in C mode for a while to see if it changes the behavior.
* STAR diagnostic, to determine if conductor plate, solenoids and/or valves appear to have issues
* conductor plate and tcc lockup solenoid replacement at next fluid change, just for good measure.
* TCU firmware update, if available
* new throttle body
* raising idle speed from 650 to something a bit higher. Not a solution to the problem, but for my case might help to avoid the problem. Although I like 650 ... engine is very quiet at this rpm.
* look for accessory belt excessive load problems, from alternator or PS pump.
My thoughts on your situation (keeping in mind that I am not an expert on this by any means .. I am just trying to make educated guesses as you are):
- If you are stalling completely at times, i.e. if the engine stumbles whenever you come to a stop, to me that would point to the $12 vacuum hose. Has that been replaced on your car?
- Have you cleaned the throttle body?
- Try replacing eng intake sensor ... they're relatively cheap and easy to swap out.
- replace plugs if you haven't in a while.
- A tranny fluid flush every 40k miles is always good preventative maintenance. If it's been longer than that since the last full flush, I suggest you do that to prolong the overall life of the tranny.
- You mentioned several STAR diagnostics? If so, they should have pointed out potential problems with conductor plate, solenoids and/or sticky valves. So can we assume they said these were okay?
Please let us know what you do next and what the results are (and I will continue to do the same).
From the above described possible solutions, from my opinion it is not an air related issue, nor ignition or PS pump etc.
On my long way trying to fix the issue please find below the interventions list I've done:
- Replace the $12 hose which was broken
- Checked and repaired all possible air leaks from the compressor gaskets (meaning the compressor itself and part around it)
- Changed the gaskets of the engine air intake (the four way air unit that comes after the throttle body)
- Cleaned the throttle body / tested with another one
- Changed the spark plugs
- Tested with new ignition coils
- Fixed air leak (also tested with another one) from the air brake pump that's just behind the engine and connects with the brake vacuum pipes.
- Throttle body learn procedure (using online DAS)
- Torque converter change
- Engine mountings replacement
- Played with calorific value of the injected fuel (still no good sign - reset to default values)
- ECU firmware update / SCN codding
- ECU replacement
- Transmission reset and gear calibration (DAS)
- TCU firmware upgrade (not available)
- 10 min on 4000 rpm - MB suggested valve cleaning procedure
- Exhaust line cleaning and catalysts control + cleaning.
- Transmission mountings replacement.
All of the above plus some minor tests that I'm not even remembering right now. What I have noticed is that this issue comes when the transmission is engaged and not when putting to N (for testing proposes) before braking pedal engagement.
Also one strange thing I noticed when changed the ECU which was taken from another W203 M271.946 but with Manual Transmission was that the issue when coming to full stop regardless of the way you drive of transmission mode (C/S) was that RPMs was very firm and no fluctuations or these kind of issues at all. When asked my friend which has now over 15 years working mostly with Mercedes and other luxury cars, he explained that maybe this comes from the fact that the ECU comes from a Manual Trans which does not give information regarding trans RPM (or something like this) and that's why ECU ignores trans RPM and both units work independently from each other.
Maybe the explanation is not quite detailed but I guess something like this really has to do with the issue. Maybe contacts from Transmission's black electronic unit (inside the tranny), other trans unit (at passengers feet) and ECU do have a latency that may be related to wet oil contacts or firmware versions between them.
Also before reprogramming my ECU with automatic trans configuration (including identity etc) I tested 0-100km/h and got it for 10s which I think it's quite good as long as it is stated 9.7 in official catalogue.
If someone can explain the communication between ECU and TCU in the Automatic Transmission models (where the communication starts and what is the input / output workflow) maybe we can come closer to the solution without wasting precious money and time which is valuable to all of us.
Hope the above description helps on the final solution.
In it, they describe a large variety of testing they did on the transmissions, looking for internal fluid pressure problems, and eventually found what they think was the problem, and came up with a solid fix for it. Unfortunately it's all internal tranny stuff, not something relatively "simple" like a conductor plate or ECU programming.
I would also like to go back to the mention of the Lucas additive which seems to have solved the problem for those folks. I am not advocating transmission fluid additives, but I would like to understand what the additive did that solved the problem in those scenarios. Glyn, do you have any thoughts on this?
At this point, I don't know but I would go more for a communication latency between modules more than transmission internal issue. As long as when ECU is set up for Manual trans and no issue at all with very firm performance, there should be in the firmware or communication some issue.
Maybe some of the members can help us make a better picture of the work schema.
This Saturday I did change my transmission oil and filter. The oil I spilled out of my transmission was pretty good in color not very dark but it had a hard smell like burned brake pads. Also removed the shift plate unit and cleaned with petrol including the solenoids and one thing I noticed was the presence of black dirt most likely caused from consumed torque converter or even transmissions friction discs.
After the cleaning and oil change the upshifting and downshifting of the car seems more stable but the rpm fluctuation in slow speeds to full stop is still present.
Anyone knows what is the main cause of the black dirt? Is it more likely to be from TC or Tranny friction discs ?