Transmision and Torque Converter Tuning discussion

[soutthpaw]

I want to start changing some of my transmission settings (See the other post I made for fueling discussion to address that side on the MPG equation) in order to get the best cruising MPG I can get for trips we do from CO to CA and back several times a year. I am doing it with the Excursion loaded with the family and luggage but not towing... Usually go up over I-70 and pretty much lock cruise control in at 75MPH I have already done the Transgo standard kit VB mod on the tranny and its using Mobil1 Full synthetic fluid TC was also drained too.
some of the parts of I70 I am thinking I will need to flip over to the 80 or 100 HP tune but will have to watch the gauges and see.... Anyhoo, back the the point of discussion here. I am really a Tranny virgin when it comes to changing anything tuning wise. though I understand the operational theory and concepts...

I have not got the Fuel Sipper tune from Bill yet so I can't compare it to stock or the 80HP which Bill said Fuel Sipper is basically the lowered and modded shift points but is about the same as the 80HP tune after about 1/2 throttle.

here is my thinking and hopefullly Cody (who is the resident tranny expert per his signature line) will let me know if I am on the ball or not
If I make the Auto tranny act more like a manual tranny it should get better overall mileage. So to do that I am thinking of making the TC lock up pretty much in every gear on acceleration and up shift. I know it needs to slip under slower speed and under load to prevent it from lagging. Inversely can I let it unlock and coast when slowing down? does slowing or coast really make much difference on the MPG (I am thinking not really) If my thinking is correct then here are a list of questions on how to approach this
I do have the AutoEnginuity Ford enhanced and a Genisys scan tool so I can do plenty of montoring when I make changes.. Just want to get a better idea of what to look at (im using the VRAA6y3 AKA PMT1) for reference here...
1. At what speeds can i set the TC to lock up for each gear

2. Which parameters do i change and to what extent to get the TC lockup without crazy hard shifting like I dropped the cluch.

3. would I need to make the TC unlock at higher throttle positions to prevent damage or lugging to the engine and tranny... if so what parts are at risk of failure and why??

4. I see there is an option to set the tranny hot fluid TC lockup over ride. I was thinking I can set it lower to lock at about 250 or less and unlock say around 220 in order to protect the tranny during testing... (I just got my gauges this week including a tranny gauge) hopefully install this weekend.

5. What is the setting for 3-4(cruise) and 4-3 (cruise) for and why is it different from the 3-4 and 4-3

6. Why no converter lockup in first or second gear below 50% (512) throttle?

7. What is the purpose/reasoning for the zig zag change in 3rd gear lock up that has 38mph at 400 TPP but then 29.5mph at 404TPP? Let me know if you need me to post the graph of it?

8. How does the trans EPC adjustments play into the whole tranny game?

Thanks
DJ

[Jackpine]

I'd like to enter this discussion, even though my contributions will be minimal.

I had always learned that for good mileage, it was important to get into the highest gear, (locked TC) and lowest RPM, as quickly as possible. This would take a bit of a balancing act, between a featherfoot that accelerates VERY slowly and a harder acceleration that gets up to speed without keeping the transmission in a lower gear (like WOT does).

And, the other thing I learned is that mild lugging for short periods doesn't damage an engine. I know I never seemed to worry about it when I had stick shifts.

So, is this all wrong? Or, is there some happy medium? And, if I'm confusing the issue that you're asking, southpaw, just tell me. I'll be happy to butt out.

Oh and, I've reduced the normal upshift/downshift points and TC lock/unlock points to the max on my truck, and it seems to be doing what I want.

- Jack

[soutthpaw]

With shift programming, there is a big difference between gas and diesel mostly due to the fact that peak torque of 500+ ftlb stock occurs at 1600 RPM... also the torque stays closer to the max after peak than before it and as HP is a multiple of RPM, HP = TORQUE x RPM ÷ 5252 so if you can get the truck to cruise at or just past its peak torque then that should be most efficient. the 7.3's seem to have a sweet spot around 2000rpm. That's one reason I am thinking it would be beneficial to lock the TC early as possible on an empty truck that I rarely drive past 1/4 throttle 95% of the time. there is more than enough torque to move the truck effortlessly.

[cleatus12r]

Originally Posted by soutthpaw

I have not got the Fuel Sipper tune from Bill yet so I can't compare it to stock or the 80HP which Bill said Fuel Sipper is basically the lowered and modded shift points but is about the same as the 80HP tune after about 1/2 throttle.
I can't give you ANY advice on what to do about "fuel sipper". Personally, I can't stand the way "economy" tunes shift and I try very hard to have my transmission shifts perform in exactly the inverse of what economy programs are supposed to do. Typically, a mileage-based tune is going to have a responsive accelerator pedal and stock shift points. Since the APP is now lower for any given rate of acceleration and shift points are based on APP, the transmission shifts earlier.

If I make the Auto tranny act more like a manual tranny it should get better overall mileage. So to do that I am thinking of making the TC lock up pretty much in every gear on acceleration and up shift. I know it needs to slip under slower speed and under load to prevent it from lagging. That is a very good way to do it. It's not always that easy though. Causing the torque converter to lock during upshifting will ALWAYS increase shift firmness unless other means are used to control firmness like torque reduction (I LOVE THAT) and shift pressure. Then you run into excessive slip times which is not good. Getting the torque converter unlock/upshift schedule perfect as to not cause a "bump" or "double shift" feel would be really difficult so the best option would be to lock the torque converter in 2nd, leave it locked, and find the best trade off in shift feel. Inversely can I let it unlock and coast when slowing down? does slowing or coast really make much difference on the MPG (I am thinking not really)Actually, using the engine braking (or what bit of engine braking we have) SAVES fuel. It's definitely a negligible amount, but it saves fuel nonetheless. When you coast, the PCM will command about 4mS of injector pulsewidth. This is not enough time to open the injector and inject fuel. During coast, you've probably noticed that the injectors go silent until around 1300 RPM when they start clicking again. When the engine is allowed to idle, it's ALWAYS using some amount of fuel. If my thinking is correct then here are a list of questions on how to approach this
I do have the AutoEnginuity Ford enhanced and a Genisys scan tool so I can do plenty of montoring when I make changes.. Just want to get a better idea of what to look at (im using the VRAA6y3 AKA PMT1) for reference here...
1. At what speeds can i set the TC to lock up for each gear.You can set the speeds in the torque converter lockup functions. It won't be an accurate setting and will require fine tuning. Also keep in mind that acceleration rate will wreak havoc with your TC lock speeds. Say for all intents and purposes that you have a straight (actual speed) lockup point of 35 MPH across the board. That doesn't mean that the TC will lock at 35 MPH under all circumstances. If I could guarantee that the TC would lock in 3rd gear at 37 MPH no matter what, I would do it.

2. Which parameters do i change and to what extent to get the TC lockup without crazy hard shifting like I dropped the cluch. Torque table map (lower = softer), Torque converter lockup rate, etc.

3. would I need to make the TC unlock at higher throttle positions to prevent damage or lugging to the engine and tranny... if so what parts are at risk of failure and why?? Typically (and this is a BIG typically), it is common practice to make the TC lock earlier (lower speeds) at higher APP settings just because it keeps the transmission alive because excess fluid coupling slippage creates a lot of heat. Besides, the factory torque converters aren't exactly great for power transfer....but that was a measure for the engineers to save the transmission service life.

4. I see there is an option to set the tranny hot fluid TC lockup over ride. I was thinking I can set it lower to lock at about 250 or less and unlock say around 220 in order to protect the tranny during testing... (I just got my gauges this week including a tranny gauge) hopefully install this weekend.If you hit 250 degrees, you've damaged the fluid. This is simply a "save the transmission" setting. It's certainly not something you're going to want to base your TC lockup scheduling on.

5. What is the setting for 3-4(cruise) and 4-3 (cruise) for and why is it different from the 3-4 and 4-3 I have yet to find a reason to change this.

6. Why no converter lockup in first or second gear below 50% (512) throttle?
It's meant for towing at this point. It goes back to the fluid coupling and slippage/heat. You can change the APP settings in shift functions to command TC lockup at any accelerator position. However, once again you're stuck with the laws of acceleration rate and actual lockup points.
7. What is the purpose/reasoning for the zig zag change in 3rd gear lock up that has 38mph at 400 TPP but then 29.5mph at 404TPP? Let me know if you need me to post the graph of it? Same answer as above. Once you hit a certain APP, the PCM assumes you're under one hell of a load. Loads and slipping fluid couplings don't mix so locking the torque converter gets the power to the ground and gets rid of the heat.

8. How does the trans EPC adjustments play into the whole tranny game?Electronic Pressure Control. Higher pressures, firmer shifting and more clutch holding pressure....basically. Don't go crazy here. There's no need to really command a solid state EPC setting higher than factory. The computer is going to make changes to that depending on your shift TV settings and torque table changes anyway.

Thanks
DJ

See comments in red.

[soutthpaw]

Thanks for the reply, A lot of useful info there. Glad to see my thinking was on track... As for the Hot lockup over ride i couldnt understand why the factory setting is like 272F or something like that.. the fluid is long since toast at that setting..... what would be a safe temp just as a precaution? 220F?

So there really at higher RPM and load its best to keep the torque converter locked? then it should downshift before any lugging problems. if that does occur then I need to change the shift points to get the downshifts when needed right?

I am gonna have to drive it some and keep track of when the TC locks up at my usual drivng speeds and habits. A lot of the speed limits aroung my house are 40mph which on the original chip caused all kinds of strange shifting. it didn't like 40, 45was much better. it did seem better on the short trip to get pizza yesterday but will have to do more driving to see. so will monitor the TC slippage with scan tool when im out and about
I know I want to get the light throttle shift point for 4th down just under 40mph so i can keep it in OD on a lot of the local roads..

[cleatus12r]

Originally Posted by soutthpaw

Thanks for the reply, A lot of useful info there. Glad to see my thinking was on track... As for the Hot lockup over ride i couldnt understand why the factory setting is like 272F or something like that.. the fluid is long since toast at that setting..... what would be a safe temp just as a precaution? 220F? That would be safe.

So there really at higher RPM and load its best to keep the torque converter locked? then it should downshift before any lugging problems. if that does occur then I need to change the shift points to get the downshifts when needed right?Yes, the torque converter will be commanded unlocked under load once a minimum speed has been reached...unless the unlock points are lowered in the tuning.

I am gonna have to drive it some and keep track of when the TC locks up at my usual drivng speeds and habits. A lot of the speed limits aroung my house are 40mph which on the original chip caused all kinds of strange shifting. it didn't like 40, 45was much better. it did seem better on the short trip to get pizza yesterday but will have to do more driving to see. so will monitor the TC slippage with scan tool when im out and about
I know I want to get the light throttle shift point for 4th down just under 40mph so i can keep it in OD on a lot of the local roads..Unless specified in an undefined parameter, you won't be able to command 4th gear below 45 MPH. It's not possible. As such, it's not possible to inhibit a light-throttle 4th gear upshift at 45 MPH. Unless I am mistaken of course.

See replies in red.

[cleatus12r]

Oh, I forgot to mention that the ONLY time you'll see 4th gear below 45 MPH is when the PCM is in "cold transmission" mode.

You will find that before the transmission warmup (delta TFT @ startup vs. current) takes place, 4th gear will be commanded around 35 MPH. However, it's not useful since torque converter clutch operation is inhibited at this time.

[cleatus12r]

Don't look over the fact that a lower RPM for any given road speed is going to put more load on the engine.....in some instances, it is counter-intuitive to lower the operating RPM. I wouldn't try (if it were possible) a 40 MPH overdrive shift.

Case in point:

At 55 MPH in 3rd gear on level surfaces, I will see a very low EGT reading. However, in 4th gear just to maintain 55 MPH will result in higher EGT. I'm not saying that it's burning more fuel in 4th. However, I just lost ALL of my boost-building and low-smoke moderate acceleration abilities since all of a sudden I'm running a lot less RPM. Less fuel at a faster rate or more fuel at a slower rate....it's your call I guess.

If you could find a way to run a 40 MPH 4th gear setup, it would probably be wise to tune in a 4-3 downshift that occurs at a decent speed/APP as well (like anything less than 10% APP). If your low boost fueling is too high and the transmission won't downshift until you're running a decent amount of APP, you'll get a ton of smoke, no acceleration, and a really hard downshift when it does occur.