Transmission: question about adaption

[monochamus]

Please, let me know WHY is so critical do the adaptation to aut. transmissions
Which issues may carry do not do it??
Thanks again masters

[billr99]

My understanding is that the adaptation process is designed to establish baselines as far as all the parameters used by the software to determine when to shift. Taking into account the physical condition of the gearbox, the process monitors things like line pressure, engine vacuum, etc. at given RPM with the goal to have shifts at an optimum point of efficiency and smoothness. In theory, the process also works around set values in regard to fluid temp and the RPM at the point of shift, i.e. 1600 RPM. Once the process is completed and the baselines established, the software continues to monitor operations and "learns" (or modifies) the shift parameters to adapt to driving techniques, transmission conditions, etc.

Back in the day, auto transmission used only things like engine vacuum and revs, throttle position and line pressures to determine shift points. Apparently, those methods weren't efficient enough although you didn't have to screw with electronics to get them to shift properly. Now just like in many things we rely on electronics and software to make things "better".

Hopefully others more versed in this subject will speak to this subject as I know my explanation is very basic.

Cheers,

Bill

[howardc64]

Interesting question! We've all known to do this... but why

Do we know if there any monitors like line pressure to enable a feedback loop? I know there isn't any to provide any kind of reading as a pressure gauge is necessary to diagnose line pressure issues from the valvebody. But maybe there are mechanical feedback loop in the hydraulic circuits? Maybe someone with good hydraulic background can provide some insight.

I know of no vibration sensors that might detect harshness of the shift. Only sensors in this transmission are

- ATF oil temperature sensor
- Likely transmission output speed sensor and engine input speed sensor. Seems to be in all electronically controlled auto trannys these days.

So it seems like adaptation can really only accomplish adaptation between engine output, vehicle speed, and acceleration/decel rate. The transmission should know what gear its in when the car is rolling by simple calculation between vehicle, engine and transmission output speed. This is probably how it knows "when" the shift has completed. Maybe it can detect shift harness using these calculations as well? Any adaptation of solenoids to ATF viscosity, line pressure or shift vibration would require sensors and fed back to software for adjustment. I'm just not aware any such sensors exist.

[billr99]

Per the Sonnax document on the AW50-55 transmission:

"The TCM (Transmission Control Module) commands the solenoids to obtain the required ratio. It also controls the line pressure and the apply and release pressure for the torque converter clutch. The input signals from the sensors act to feed information to the TCM so that it can obtain the best ratio to give maximum fuel efficiency."

"Pressurization of the clutches and brakes are adjusted by reading the change of speed of the transmission input shaft during the shifting process and comparing the values calculated in the TCM."

"SLT - This is the line pressure solenoid. It is a normally open three port type solenoid. The TCM controls this transmission using 300 hz commanding current fro 0.0 to 1,1 amps. The TCM uses current measurement to determine pressure."

"SLS - This solenoid is the shift pressure solenoid. It is similar to the SLT solenoid in that it is a three way ported solenoid and runs at the same frequency and current characteristics. It is used to buffer the shift and is adjusted dependent on load requirements and driving conditions.

"TFT - The transmission fluid temperature sensor is an integral part of the transaxle internal wire harness assembly The TFT is a NTC thermister which changes its value based on the transmission oil temperature. The TFT has 5 volts feed to it and due to variants of resistance caused by temperature, it feeds a variable voltage back to the TCM. When the oil temperature is cold, a high resistance is evident. As the oil heats up the resistance lowers. The TCM uses this resistance to calculate the oil temperature in the transmission. This signal is used by the TCM to modify the shift quality and the TCC operation."

"Output shaft speed sensor. - The output shaft speed sensor is a Hall effect sensor. Hall effect sensors usually have three wires but in this case, the sensor only has two wires. The sensor is mounted in the case by the park gear by the front differential transfer gear assembly. The sensor is supplied with 0.6 volts to activate it. As the vehicle moves the toothed gear passes the sensor and produces a square wave or frequency. The TCM uses this signal to calculate the vehicle road speed."

"Input shaft speed sensor. - The input shaft speed sensor is of the same construction as the Output shaft speed sensor.
The reluctor for this sensor is the teeth on the forward / direct clutch housing. The output from this sensor is used by the TCM to adjust and determine transaxle shift patterns, line pressure TCC apply pressure and gear ratios. It is also used to determine TCC slippage."

Finally in regard to the adaptation process "This transmission relies on adaptive data to properly adjust the shift pressure."

Cheers,

Bill

[howardc64]

wow, cool! ATF temp sensor = viscosity which make sense. Didn't know linear solenoid's position (and with position can derive pressure) can be determined by measuring the current. Very cool. Found the following info in the link below. See "Determining Solenoid Position"

http://www.analog.com/library/analog...solenoids.html

I wonder if VIDA/DiCE can read the linear solenoid's position/pressure, seems like it would be helpful for a more definitive diagnostic on line pressure problems.

[monochamus]

wow, cool! ATF temp sensor = viscosity which make sense. Didn't know linear solenoid's position (and with position can derive pressure) can be determined by measuring the current. Very cool. Found the following info in the link below. See "Determining Solenoid Position"

http://www.analog.com/library/analog...solenoids.html

I wonder if VIDA/DiCE can read the linear solenoid's position/pressure, seems like it would be helpful for a more definitive diagnostic on line pressure problems.

I understand that DICE can measure those parameters. Today arrived to me my DICE clone from china. Let's see how it works and if it has that feature

[monochamus]

I could look for some info in the web but I knew that HERE I would find the answer and better applied to our cars.
THANK YOU GUYS VERY MUCH
muchas gracias amigos son maestros en la materia= thanks friends you are masters in this topic

[perkinscl]

Per the Sonnax document on the AW50-55 transmission:


"TFT - The transmission fluid temperature sensor is an integral part of the transaxle internal wire harness assembly The TFT is a NTC thermister which changes its value based on the transmission oil temperature. The TFT has 5 volts feed to it and due to variants of resistance caused by temperature, it feeds a variable voltage back to the TCM. When the oil temperature is cold, a high resistance is evident. As the oil heats up the resistance lowers. The TCM uses this resistance to calculate the oil temperature in the transmission. This signal is used by the TCM to modify the shift quality and the TCC operation."

Hmm, can we rig up a gauge that shows the ATF temp?

I can tell a definite difference with shifting when I've been going through the gears a lot (hilly PA backroads). My lockup is terrible. I've used the Gibbons ATF flush 2x (60K & 90K miles) and didn't reset my counters or perform adaptations either time. Next time (which is soon, I can tell my shifting isn't as "crisp"), I'll do both.

[vtl]

I wonder if VIDA/DiCE can read the linear solenoid's position/pressure, seems like it would be helpful for a more definitive diagnostic on line pressure problems.

No, it can't (do it reliably). Affirmation of this fact is all rebuilt valve bodies Generally, you can measure how linear solenoid responds to PWM modulation at given temperature, bushings and spring condition, then do approximation of the position by knowing input modulation parameters. Once any parameter is off - the estimation is incorrect. If only solenoid would have a feedback loop providing definitive armature position, valve bodies would probably run almost forever, because most of the mechanical glitches in solenoids would be possible to neutralize in software.