Slightly nagging Transmission problem 5G-Tronic 722.6 Five Speed Automatic Transmission

[charlysays]

Thanks for that info. I'm in Cardiff Wales. There are transmission specialists locally.

I can do the Conductor Plate and the Valve Body myself but getting inside the transmission mechanics that's much more difficult. I can do some electronics but really difficult chasing an intermittent fault with limited documentation.

I am considering the purchase of an ICARSOFT that you mentioned in another thread. The ODBII reader I have cannot read transmission codes.

Lets hope that the existing ATF fluid is the nice pleasant variety lol

I can confirm that the icarsoft mb v1.0 and the red 38 pin multiplexer adapter will read all the main systems on your car including reading trans codes and clearing them.
I got mine for 50 quid used as new on ebay and then 35 for the adapter. It's money well spent because you can deal with most fault finding yourself forever more for the cost of a single maindealer code read or 2x indie code reads.
My car however is a bit of a crossover being a very early facelift W202 so to get into the ABS and ECU for example takes some trial and error until you find an option that will communicate- in other words when you select the vehicle in the menu you may not be able to access all systems if icarsoft think the car should have a different module from what it actually has.

 

[rich.g.williams]

Grand theory, however you are experiencing a fault of some kind that is not effecting many other running the same drive train, that being the case infers that the design itself is sound and that in Yr case there is an as yet unidentified issue..
Perhaps a tranny swap (borrow) and or tc is the answer to prove the point as to where the defect is , control of, or faulty part.

"The clutch is not too small for full power transfer. For the A2112500902 Torque Converter there are two friction rings thicker and of a diameter as large as any clutch or brake rings in the transmission.

The problem is most likely things like "ride comfort demands made on the drive train with regard to its vibration behaviour" Also pushing maximum engine torque through the Lockup clutch alone likely creates vibration/harmonics in the drivetrain that are likely damaging to the engine/transmission/flexplate"

My reply is what WIZ says (nothing to do with my car). My comment as regards the TCC clutch is based on actually physically seeing and handling the clutch - it is beefy. WIZ explains that they do not maintain full TCC Lockup beyond a certain throttle opening because direct coupling (without the TCC hydraulic insulation) creates drive comfort issues. I deduce that a full TCC Lockup at high revs and full throttle opening are likely damaging to the engine/transmission/flexplate. The TCC Clutch can handle it fine (don't forget that the transmission is also a torque multiplier and in first gear torques inside the transmission way exceed torque at the TCC Clutch plates).

As regards swopping the transmission I'm fine with swopping this a few times and even renewing clutch rings etc if that's the price for sharper shifts. Believe me if you wanted to get going in a hurry you wouldn't bother too much with Mod pressure - just let it mostly stay at maximum - shifts would be close to instant. Also leaving the TCC fully Locked Up more of the time would be great even if it shakes a bit

 

[rich.g.williams]

I can confirm that the icarsoft mb v1.0 and the red 38 pin multiplexer adapter will read all the main systems on your car including reading trans codes and clearing them.
I got mine for 50 quid used as new on ebay and then 35 for the adapter. It's money well spent because you can deal with most fault finding yourself forever more for the cost of a single maindealer code read or 2x indie code reads.
My car however is a bit of a crossover being a very early facelift W202 so to get into the ABS and ECU for example takes some trial and error until you find an option that will communicate- in other words when you select the vehicle in the menu you may not be able to access all systems if icarsoft think the car should have a different module from what it actually has.

Thank you very much, I just had a look at eBay and the iCarsoft MB V1.0 are selling for not much money.

I was considering the purchase of an ICarsoft a while back then I noticed that the V2.0 (on the iCarsoft website) shows a miniUSB connector (rather than a microUSB or even an USB-C) that put me off a bit lol.



My generic ELM Bluetooth OBD reader isn't showing up any generic ETC related error codes but I should get a proper code reader for MB.

Does your W202 have a 722.6 transmission?

 

[rich.g.williams]

the car has done 45K miles.
Any idea if the transmission fluid has been changed yet.

About 93% of the ATF is new now.

The jolt is occasional and only when the engine and transmission are hot. I have almost dismissed the Torque Converter as the cause and am reading up on how the B2 brake is handled - its the only clutch/brake that has two pistons (counter pressure and apply) and only one to have its own dedicated hydraulic valve.

"GARAGE SHIFT - Another interesting aspect of this transmission is the way in which a smooth garage shift into drive is accomplished. The B2 clutch has a double piston as you can see in Figure 85. Notice how in Figure 86 that as the selector lever moves from Neutral into Drive, the MV 3-4 solenoid (Y3/6y4) duty cycles which pegs the B2 Shift Valve to the end of the bore. This allows the fluid pressure which fills the apply side of the B2 piston to also fill between the apply and counter pistons. This counter pressure opposing apply pressure reduces the apply force of the piston onto the B2 clutches. Once the selector lever has rested in the Drive position (See Figure 97), the MV 3-4 solenoid shuts off. This now allows the B2 shift valve to go into regulation (The B2 shift valve can act as a regulating valve with the absence of MV 3-4 solenoid oil due to the difference in the valve’s land diameters and the metered one-way air bleed capsule in the B2 counter piston). This brings the counter pressure circuit down to about 0.5 bars or 7.25 psi while allowing full pressure to act on the B2 apply piston for a firm hold on take off"

My theory is that the so called garage shift (as explained by the US ASTG manual) is occasionally not executing as it should for reason as yet undiagnosed. I'm going to do some more tests this week.

 

[rich.g.williams]

Just a thought. is mod press solenoid designed on, off only or should it be modulated take up by trans ecm

The B2 brake counter pressure piston has a one way spring/ball bearing valve in the actual piston, would you know what its likely there for please? I read that its supposed to be at the 12 o clock position.

 

[ajlsl600]

Guessin a bit. Not seeing schematic but oil pressure pushes against ball/ spring un seating it allowing flow, when source of pressure is terminated ball is seated again by spring. Maybe leaving oil on closed side thus reducing time for flow/ pressure to fill what could be a void next time pressure/flow is demanded
I hasten to add I am mainly guessing. So by all means take this with a pinch of salt.....
The 12 o'clock position maybe prevents seapage?????

 

[charlysays]

Thank you very much, I just had a look at eBay and the iCarsoft MB V1.0 are selling for not much money.

I was considering the purchase of an ICarsoft a while back then I noticed that the V2.0 (on the iCarsoft website) shows a miniUSB connector (rather than a microUSB or even an USB-C) that put me off a bit lol.


View attachment 84533
My generic ELM Bluetooth OBD reader isn't showing up any generic ETC related error codes but I should get a proper code reader for MB.

Does your W202 have a 722.6 transmission?

I had an icarsoft mbv.2 and for my car atleast it didn't do anything extra over the v.1. so sent it back in the end and kept the used V1. Yes mini USB on them for update via computer, although they work straight out of the box with no updates. Mini USB is still lightyears ahead of the tech in the car though lol. Its a very cheap code reader tbh, but it does the job pretty well. Would recommend buying used though as there are loads up for sale in mint condition having been used only a few times.
So far I've use mine the most for clearing codes from ECUs I've bought to immo off and remap.
When you buy one it's worth downloading the desktop application and entering the serial number to check it's genuine, allegedly there are fakes around.

 

[rich.g.williams]

I had an icarsoft mbv.2 and for my car atleast it didn't do anything extra over the v.1. so sent it back in the end and kept the used V1. Yes mini USB on them for update via computer, although they work straight out of the box with no updates. Mini USB is still lightyears ahead of the tech in the car though lol. Its a very cheap code reader tbh, but it does the job pretty well. Would recommend buying used though as there are loads up for sale in mint condition having been used only a few times.
So far I've use mine the most for clearing codes from ECUs I've bought to immo off and remap.
When you buy one it's worth downloading the desktop application and entering the serial number to check it's genuine, allegedly there are fakes around.

It's a matter of putting what I want first. I appreciate your advice as regards the iCarsoft. When I went into the thing in more detail I quickly realised that they are having a laugh.

All I want is open publication of CAN bus for all the car's electronics. Then also want a cable with car specific connector - CAN to logic chip - logic to USB chip - going to an USB-C connector.

Don't need some company holding all the keys (individual product for every car) and fobbing me off with ancient mini USB.

Notice you are in Pembrokeshire, I was born in Cardigan and know Pembroke reasonably well - like Cardiff also

 

[Vanlata203]

Its more involved than that.

As long as engine RPM are high enough the Lockup clutch locks to direct drive (in any gear). If power applied gets high the Lockup clutch has to allow some slipping and even fully unlock near maximum power.

As a driver I would want it to fully lock under light loads in 4th and 5th gear when road speed gets above about 35 mph, especially fully lock on the motorway (so that engine rpm stays as low as possible).

If the graph taken from WIZ is right its saying that the driver can control Lockup to some extent by accelerator Pedal Position.

View attachment 84513

Precis of info from wiz:-

Blades of the impeller spin ATF outwards to the turbine wheel causing it to rotate. The turbine wheel blades direct the oil onto the blades of the stator, which in turn push the oil back to the impeller. This diversion at the stator (which is supported against the transmission housing via the freewheel), produces an increase in torque. At the maximum speed difference between the impeller and turbine wheel the torque conversion achieves its maximum value of about times two.

View attachment 84512


The torque converter lockup clutch helps to reduce fuel consumption by reducing torque converter slip. This stands in contradiction to the ride comfort demands made on the drive train with regard to its vibration behavior. The task of the electronic transmission control is therefore to close the clutch in all driving situations relevant to fuel consumption, still ensuring that engine vibrations are isolated from the drive train.


-

For some time I was troubled by this case, when it should be open, slipping, close. With me, when it came to second gear, the car was directly in close. It was rougher, there were more vibrations, but it started better. In addition, it has a remap and is 430nm. measured on a dyno.
After replacing the sensor board due to a defect, it stopped locking completely. It always sits open until it slips, never until it closes. I spoke to specialists and they said there is no problem, since then there is no vibration and it is on a pleasant ban, maybe it is still not that good start as before but it is tolerable.
Through full load diagnostics I can't get more than 370nm at the moment, otherwise the locking valve behaves adequately and when slipping does not allow a difference greater than 100 rpm.
I'm not sure, but I think I read that recoding can affect the lock. With sprinter, it thinks it's in close from early on.

 

[ajlsl600]

For some time I was troubled by this case, when it should be open, slipping, close. With me, when it came to second gear, the car was directly in close. It was rougher, there were more vibrations, but it started better. In addition, it has a remap and is 430nm. measured on a dyno.
After replacing the sensor board due to a defect, it stopped locking completely. It always sits open until it slips, never until it closes. I spoke to specialists and they said there is no problem, since then there is no vibration and it is on a pleasant ban, maybe it is still not that good start as before but it is tolerable.
Through full load diagnostics I can't get more than 370nm at the moment, otherwise the locking valve behaves adequately and when slipping does not allow a difference greater than 100 rpm.
I'm not sure, but I think I read that recoding can affect the lock. With sprinter, it thinks it's in close from early on.

Can u get the remap off and see how it behaves

 

[pgh13]

It's a matter of putting what I want first. I appreciate your advice as regards the iCarsoft. When I went into the thing in more detail I quickly realised that they are having a laugh.

All I want is open publication of CAN bus for all the car's electronics. Then also want a cable with car specific connector - CAN to logic chip - logic to USB chip - going to an USB-C connector.

Don't need some company holding all the keys (individual product for every car) and fobbing me off with ancient mini USB.

Notice you are in Pembrokeshire, I was born in Cardigan and know Pembroke reasonably well - like Cardiff also

Don't know if you've seen, there are some YT videos on accessing canbus using ESP32 microcontroller boards

 

[rich.g.williams]

For some time I was troubled by this case, when it should be open, slipping, close. With me, when it came to second gear, the car was directly in close. It was rougher, there were more vibrations, but it started better. In addition, it has a remap and is 430nm. measured on a dyno.
After replacing the sensor board due to a defect, it stopped locking completely. It always sits open until it slips, never until it closes. I spoke to specialists and they said there is no problem, since then there is no vibration and it is on a pleasant ban, maybe it is still not that good start as before but it is tolerable.
Through full load diagnostics I can't get more than 370nm at the moment, otherwise the locking valve behaves adequately and when slipping does not allow a difference greater than 100 rpm.
I'm not sure, but I think I read that recoding can affect the lock. With sprinter, it thinks it's in close from early

There seems to be a big difference between how Petrol and Diesel cars are handled as regards TCC lockup. Also most of the vibration problems I read about concern Diesel engine MB cars and the worst problems seem to be with Sprinter Vans.

Diesel engine RPM range is less than for Petrol and the two types of engines have different Torque vs RPM characteristics.

As I read/deduce - the ETC continuously monitors engine RPM (via CAN bus) and compares with n2 n3 speed sensors, it then adjusts TCC Lockup solenoid PWM in a feedback loop to keep the RPM differential across the TCC to a certain amount according to maps (that include torque etc). If this is correct it follows that any RPM speed sensor errors will affect TCC Lockup, there could be the basis of an explanation for TCC Lockup problems somewhere in that.

Maybe have a look at this link:-

TCC Lockup

-

 

[rich.g.williams]

Don't know if you've seen, there are some YT videos on accessing canbus using ESP32 microcontroller boards

Thanks I will have a look. I have come across the ESP32 because I had a long discussion with a young man after I saw his NAG52 project, he has designed a new ETC for the 722.6 transmission and it looks very interesting with a lot of good ideas, he has studied the whole thing and is a talented expert with the 722.6 and car electronics etc. Here are some links:-

The NAG52 ETC

NAG52 YouTube Video

rnd_ash NAG52

rnd_ash POSTS

-

 

[rich.g.williams]

I ran some tests, fitted a 10 Ohm resistor across the pMod solenoid, this increases the current through the pMod solenoid thus reducing the pMod pressure (and therefore line pressure). This resistor could be switched in and out as required.

By recording the outputs from the two speed sensors n2 and n3 I soon realised that when taking up drive the cold transmission was taking about 500mSeconds whereas when very hot it was taking sometimes less than 200mSeconds. Switching the resistor in would increase the time to over 800mSeconds.

With the resistor connected the bump did not happen (that is at least during my tests).

I attach a comparison diagram showing the upper trace with resistor connected (pMod minimum) and the lower trace with the ETC operating normally. The diagram is showing that as drive is taken up the n2 speed is dropping and almost reaches zero, at the same time the car is beginning to move forward and the speed of n2 increases again as the car moves off.

All through this, 1st gear is already engaged apart from B2 brake at the rear of the transmission. Control of what B2 is doing is important. It has to pick up drive slowly enough for the torque converter to absorb change without stalling too abruptly. By the time B2 is fully engaged either the car is moving forward or (if the driver has his foot on the brake) the torque converter is slipping with the car not moving (in this case n2 will be reading zero rpm).

The comparison diagram that follows shows a filtered output from n2, higher the speed smaller the n2 envelope, as n2 starts to stop its envelope reaches maximum. Then as the car moves n2 speed increases and the envelope reduces. Notice how there is a slight oscillation as car starts to move.

 

[rich.g.williams]

Here is a short extract from an n2 n3 recording. In first gear n3 is zero, then in 2nd gear both n2 and n3 are there. To display (or play as sound) rename it to .wav file