tuners; transmission control inputs

mandkole

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guys, some of you may have been reading my posts on my recent TCC issues. Im not completely certain, but it really seems that the locking/unlocking issues have increased with the larger tires. This is not a trans issue, the PCM is commanding the unlock. (The speedo has not been recalibrated.)

My issue is that the converter clutch seems to be much more sensitive to the PCM unlocking it with the throttle input. Ive been told the tuning inputs affect this and tuners will often increase the ability to unlock to keep a big single able to spool. What Im wondering is if the TCC unlock sensitivity was increased, but now the tire size increase has increased load to where it requires more throttle and has made it even more prone to unlocking now.

Still not totally sure its not the trans, but want to have a little conversation about the changes in the way the PCM commands the controls.
 

Mark Kovalsky

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but now the tire size increase has increased load to where it requires more throttle and has made it even more prone to unlocking now.
That is very likely. Larger tires do increase the load, and whether you know it or not for any given road speed you are now pushing the accelerator further, which gets you closer to the unlock curve. Once you press it far enough to cross that curve it unlocks.

There are two ways to get it back to where it was. The first way is to change the axle ratio by the same percentage as the new tires are larger than the original.

The second way is to create custom lock/unlock/upshift/downshift schedules to compensate for the tires. This is what I call a work around, you probably won't like the way it drives.
 

mandkole

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What is this unlock curve? Why does the PCM command the TCC to unlock? Is the command a controlled input of the calibration?
 

Mark Kovalsky

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There are tables in the software that control when the torque converter locks and unlocks. They are pedal position vs. vehicle speed. They also get modified by other inputs, but they are minor. If you plot these tables I find they are easier to understand, so I called it a curve.

The torque converter will unlock for different reasons. Below a certain engine RPM there isn't enough flow from the trans pump to keep the converter clutch fully applied, so it unlocks to prevent the clutch from slipping. Slipping will damage the clutch. This RPM is about 1300.

It is also unlocked when more acceleration is requested, indicated by the driver pushing his/her right foot further down. Unlocking allows the engine to rev, often getting it to a better place on the torque curve, and unlocked the converter can provide some torque multiplication.

These commands are controlled by the calibration. That's what I did at Ford, I developed calibrations.
 

mandkole

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Thanks-- I understood it a little, but that helps. The tuning I have has always worked fine and Ive just not taken the time to learn more about it.

The conditions where its more apt to unlock is right after it locks for the first time during casual acceleration (interstate on ramps) or on lower speed roads with hills. Ive got no issue with the unlocking as that makes sense, but it quickly wants to relock again then unlock. Its never done that until the last couple of months at about the time of the new 34.5" tires.
 

Mark Kovalsky

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The larger tires moved your operating point at that speed closer to the unlock point. A small movement of your right foot might cause it, or the lock/unlock curves don't have enough MPH between them so you keep crossing both of them.
 

Dirtclod

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I have the same size tired on my 01. I have a new tranny with HD upgrade. My mechanic who installed it said its the same build that goes in th motor home. I know I need some tuning and as soon as I get my truck out of the shop from a crash and finish my fuel system and injector orings I'm going to dp tuner to get their 16 pos. ok Mark my question for you:Do you recommend dropping gear to 410? Or fix with tuning? My front left wheel hub assembly is messed up and I ain't spending a dime on that 50. I'll just get a d60 from a guy that's pm'd me. Before I do that I'll need to know what gear. Any advice is greatly appreciated!
 

Tom S

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If you shoot me a PM with your email I can send you a some excel stuff with shift points and lockup overlaid to help get a visual on this.
 

Tom S

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There are tables in the software that control when the torque converter locks and unlocks. They are pedal position vs. vehicle speed. They also get modified by other inputs, but they are minor. If you plot these tables I find they are easier to understand, so I called it a curve.

The torque converter will unlock for different reasons. Below a certain engine RPM there isn't enough flow from the trans pump to keep the converter clutch fully applied, so it unlocks to prevent the clutch from slipping. Slipping will damage the clutch. This RPM is about 1300.

It is also unlocked when more acceleration is requested, indicated by the driver pushing his/her right foot further down. Unlocking allows the engine to rev, often getting it to a better place on the torque curve, and unlocked the converter can provide some torque multiplication.

These commands are controlled by the calibration. That's what I did at Ford, I developed calibrations.

Mark did you strictly do the transmission side of the calibrations? If so I would like to hear more about the process, like was this a big team that works on it? Did you do most of the work on the road on in a dyno room? I am asking from the perspective of being the driver while working on some tunes and it takes a lot of time to get the trans tuning worked out.
 

mandkole

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PM sent Tom-- thank you!


Mark,
What else could the trans sensors be picking up that would drive the PCM to unlock? You mentioned line pressure-- I wonder if the line pressure is dropping at moments where the PCM wants to protect by unlocking, but then once unlocked it quickly realizes that it should be locked . Ive read that if the PCM is sensing converter slip it could drive it to unlock, or, could this be an issue?

My next task is to run it on AE to see converter slip and I may hook a pressure gauge up as well. I think the issues could be mechanical and Im at the very early points of failure. It feels like a trans pulling is in the future.
 

Mark Kovalsky

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ok Mark my question for you:Do you recommend dropping gear to 410? Or fix with tuning?
That's a 10% change. So at a certain speed if you are now turning 1500 RPM with a 4.10 you will be turning 1650. Not a big change.

Mark did you strictly do the transmission side of the calibrations?
At Ford, yes, only transmission. Before I worked at Ford I worked for Roush Industries (yes, THAT Roush) doing engine calibrations. That was from 1982-1988. It was at the early days of EEC-IV. My first assignment was on the second program at Ford to have EEC-IV. We were only a couple months behind.

If so I would like to hear more about the process, like was this a big team that works on it? Did you do most of the work on the road on in a dyno room? I am asking from the perspective of being the driver while working on some tunes and it takes a lot of time to get the trans tuning worked out.
It depended on the program. When I worked on the '03-'07 5R110 diesel calibration there were two of us sharing the work. All other calibrations I worked on before that I was it. The big team was me. We had a larger team, but everyone worked on their assignment, and shared information throughout the team.

Ford was trying to move calibration from on the road and test track into an engine/transmission dyno cell when I left Ford. I have my doubts about how successful that can be. A large portion of the tuning is tuning the shifts to the vehicle. That is very hard to do if you don't have a vehicle.

I usually worked on a calibration for about a year until it was released for production. We had to hit all the environmental conditions that you, the customer, could possibly run into. We went to Yucca, AZ and/or Death Valley in the summer, somewhere REALLY cold in the winter (Yellowknife, NT, Canada, Thompson, MB, Canada, Timmons, ON, Canada etc.) Denver for high altitude, and southwestern Florida for high humidity. We usually did this trip right after the cold weather trip sort of as a reward for surviving -20F to my personal record, -48F. And that wasn't wind chill, that was the actual temperature.

Mark,
What else could the trans sensors be picking up that would drive the PCM to unlock? You mentioned line pressure-- I wonder if the line pressure is dropping at moments where the PCM wants to protect by unlocking, but then once unlocked it quickly realizes that it should be locked . Ive read that if the PCM is sensing converter slip it could drive it to unlock, or, could this be an issue?
The PCM doesn't know what line pressure is. It knows what it told the EPC to set line pressure at, but there is no feedback to know if it happened.

If the PCM detects converter slip it will unlock it and set a code. The PCM looks at engine temp, trans temp, pedal position, rate of pedal position movement, vehicle speed, engine speed, barometric pressure, and probably a couple others I can't think of at the moment to determine how to modify the curves to make the lock/unlock decision.
 

mandkole

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If the PCM detects converter slip it will unlock it and set a code. The PCM looks at engine temp, trans temp, pedal position, rate of pedal position movement, vehicle speed, engine speed, barometric pressure, and probably a couple others I can't think of at the moment to determine how to modify the curves to make the lock/unlock decision.

Is it possible that the turbine speed sensor is suddenly giving some bad data? Id think if it was not working right it would act up more often and set a code for that as well. The p471 would only come after it attempted to unlock/lock after about 3-4 times.

Thanks again for all the assistance.
 

V-Ref

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That's a 10% change. So at a certain speed if you are now turning 1500 RPM with a 4.10 you will be turning 1650. Not a big change.





At Ford, yes, only transmission. Before I worked at Ford I worked for Roush Industries (yes, THAT Roush) doing engine calibrations. That was from 1982-1988. It was at the early days of EEC-IV. My first assignment was on the second program at Ford to have EEC-IV. We were only a couple months behind.





It depended on the program. When I worked on the '03-'07 5R110 diesel calibration there were two of us sharing the work. All other calibrations I worked on before that I was it. The big team was me. We had a larger team, but everyone worked on their assignment, and shared information throughout the team.



Ford was trying to move calibration from on the road and test track into an engine/transmission dyno cell when I left Ford. I have my doubts about how successful that can be. A large portion of the tuning is tuning the shifts to the vehicle. That is very hard to do if you don't have a vehicle.



I usually worked on a calibration for about a year until it was released for production. We had to hit all the environmental conditions that you, the customer, could possibly run into. We went to Yucca, AZ and/or Death Valley in the summer, somewhere REALLY cold in the winter (Yellowknife, NT, Canada, Thompson, MB, Canada, Timmons, ON, Canada etc.) Denver for high altitude, and southwestern Florida for high humidity. We usually did this trip right after the cold weather trip sort of as a reward for surviving -20F to my personal record, -48F. And that wasn't wind chill, that was the actual temperature.





The PCM doesn't know what line pressure is. It knows what it told the EPC to set line pressure at, but there is no feedback to know if it happened.



If the PCM detects converter slip it will unlock it and set a code. The PCM looks at engine temp, trans temp, pedal position, rate of pedal position movement, vehicle speed, engine speed, barometric pressure, and probably a couple others I can't think of at the moment to determine how to modify the curves to make the lock/unlock decision.


Mark

Your a great resource to have on these forums. Your posts are always informative and enlightening. Thanks for your contribution here.


Sent from my iPad using Tapatalk
 

UpstateDieselGuy

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I'm thinking you could clean house doing some freelance tuning for some of the tuners out there! lol I would presume that you cannot do so legally though.

Chris
 

Layson

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So when you first drive your truck and you get up to XX or so mph the converter locks then unlocks....and then locks back up? Then it doesn't do it again? Is that what I am reading?
 

mandkole

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Steven,
In either 3rd or 4th, the pcm will often command a very brief unlock after the TC was commanded to lock. It then will relock and if your still giving it a load, it will do it again.. Its always a very low throttle application (20-30%) and usually when on a light grade. Once its unsuccessfully commanded a few unlock/locks it will set a 0741 code. If I override the pcm with the TC switch, it will stay locked (but you can still see the pcm trying to command unlock/lock in same conditions). Often a code has been thrown.

The question is why is the PCM commanding unlock-- is it in the tuning or is it mechanical? I need AE to see the slip% (the scan gauge wont show it) to see if the PCM is commanding unlock due to excessive slip.

Theres a thread in the tech section that Mark K has spent a lot of time discussing.
 

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