Transmision and Torque Converter Tuning discussion
 

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:drinking::drinking:
DJ

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

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.

See comments in red.

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..

See replies in red.

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.

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.

thanks for the suggestion.. I think it was doing a 3-2 downshift not a 4-3 so i just need to fix the 3-2 downshift setting probably bring the 4-3 down around 43 or 42 mph at low throttle. need to make a log of my throttle position s though
I came up with an idea on how to get really low OD shift at a low mph. Talking with Bill a couple of days ago I mentioned I corrected my tire size setting and he told me that does not fix the RPM, only affects the shift points for the transmission... Sooooo:reddevil: you could put a different number in the tire Revs per mile and then you actually fool the tranny into thinking the vehicle is going faster than it really is so it would shift earlier
what ya think??

That would work. Of course, you're clever enough to realize that it will affect ALL aspects of shift scheduling.

yeah I would have to practically change all the shift points and throttle positon setting and lots of trial and error...:cheesy smile:

Here's a question for everyone...feel free to throw anything into the pot.

Do you feel that lugging the engine constantly (as such in a fuel economy-minded program) is the best way to gain increases in mileage?


I'll start. No.

I agree lugging is always bad. But these engines make so much low end torque that it seems in theory you could drive empty at much lower rpms than stock and still drive around fine. The followup to that is finding the right balance. And will it yield better, worse, or no change in fuel economy.
Hope Bill gets caught up soon so we can get him back on the forum and get his take on it.

But, Cody, isn't the effect different for diesels vs gas engines? (And I'm sorry I didn't qualify my original post with that caveat - I know next to nothing about diesels). My post probably seemed kind of stupid. And, I was trying to open the discussion up to diesel AND gas - but maybe that was too ambitious.

Now, I'm really NOT suggesting lugging any engine constantly, because it seems to me that you're not getting a clean, efficient burn and you're going to see maybe fouled plugs at a minimum in gas engines and possibly valve damage? But, my experience "lugging" my old stick shifters, was for a pretty minimal amount of time, maybe about 5 seconds before the engine speed would increase enough to stop the lugging.

It always seemed to me that I had to be using less fuel that way than with a downshift, followed by an upshift a short time later.

Am I out to lunch on this one? (Wouldn't be the first time)! :doh:

- Jack

well Gas and Diesel are sooo different it is hard to talk about both other than in general terms.... That's what makes Diesels so awesome:happy-dancing: Maybe we will convince Jack to get a diesel :smiley_roll1:

Lugging means you are trying to move too much weight with too little power...

as RPM increases even past the peak torque you still need less HP to move the weight because of the formula
here is a good example I found on the web
example 1: How much TORQUE is required to produce 300 HP at 2700 RPM?

since HP = TORQUE x RPM ÷ 5252
then by rearranging the equation:
TORQUE = HP x 5252 ÷ RPM
Answer: TORQUE = 300 x 5252 ÷ 2700 = 584 lb-ft.

Example 2: How much TORQUE is required to produce 300 HP at 4600 RPM?
Answer: TORQUE = 300 x 5252 ÷ 4600 = 343 lb-ft.

Example 3: How much TORQUE is required to produce 300 HP at 8000 RPM?
Answer: TORQUE = 300 x 5252 ÷ 8000 = 197 lb-ft.

Example 4: How much TORQUE does the 41,000 RPM turbine section of a 300 HP gas turbine engine produce?
Answer: TORQUE = 300 x 5252 ÷ 41,000 = 38.4 lb-ft

read it a few times and see if it makes sense... this is really the key to finding the best combination of RPM and Torque to get the best result..... you have to then look at how much torque the vehicle makes at various RPM then figure out what speeds the vehicle is traveling at using those figures
Remember Torque is an actual directly measurable value, whereas HP is a calculated figure...

Lets say my engine is in OD at 50 mph at 1600 RPM and making 500ftlb of torque (stock peak torque is at 1600)
500x1600/5252=152.3 hp
now at 2600 rpm lets say we get 450 ftlb torque
450x2600/5252=137.1hp

so even though we are making less torque we also need less power due to the higher engine speed......

sounds simple right...
except for a couple of things... we are not using Wide Open Throttle WOT most of the time when driveing... so now you look at how much throttle and hence fuel u need to get the power to move the vehicle ; so you will need less throttle to get the same amount of torque at peak torque rpm than you will at higher RPM and as the engine is spinning less times a minute you are injecting less fuel per minute at the slower speeds

Confused yet
so in the real world it comes down to trial and error!

DJ,

How about you use that fancy AE package you have and put it to use! :howdy:

Here's what you do.

1. Drive in 3rd gear at 45 MPH; no load, not accelerating. Check the Mass Fuel Desired by what the datastream says.

2. Same test...only in 4th gear.


3. Use the MFD data and calculate over time and engine speed.

4. It's not the most accurate, but it may give you an idea.

I have a Genisys sitting here, but it's cold and snowing out. :throwup:

That's actually a very good explanation of the difference between horsepower and torque, southpaw!

So, at low speeds (lugging) we need more torque to produce equivalent horsepower. Sure - and some engines like my old 427 cu in Police Interceptor were designed to produce high torque in the low RPM band so it was easy to move off from a standing start. I know diesels are weak in this regard.

But, why is a diesel so different from a gasser? Is it because the compression is so high that it "works against" the output at low rpm?

Naturally, we can only really continue to accelerate as long as the torque output of the engine exceeds the torque demand needed to maintain the current speed. And, at cruise, the torque/fuel demand is reduced, since we're no longer accelerating, but have to supply just enough to counter the force of wind resistance, friction, and other losses that try to slow us down.

The whole horsepower thing is kind of a "fiction", isn't it?

And, does the EGT go up in lugging because the fuel is "afterburning" as it leaves the cylinders? (Hasn't completed the burn during the power stroke)? Or, did it finish the burn too early, since the piston is moving too slowly? (Creating a "hot spot" effect in the cylinders that is not countered soon enough by the cooling exhaust and intake cycles)? In either case, wouldn't a gasser have the same problem?

And, getting back to the "lugging" proposition, what, specifically, is wrong with this strategy? Does it work in a gasser but not in a diesel due to the low RPM power characteristic?

I did not mean to hijack this thread and if I have, I'll start a different discussion of it elsewhere.

I'm honestly just trying to gain a better understanding of the two technologies. I'm already a diesel convert, just don't have one yet!

- Jack

Yes! that's a good approach Cody! (Your new avatar really creeps me out, you know - how does a guy with the friendly screen names of "cleatus" and a real name of "Cody" come up with such a sinister looking guy)?

Anyway, your approach is clearly the right one. At the "lugging" speed of 45 mph, which gear uses more gas? And, if the tune locked you into the "higher gas use" gear at that constant speed, then it's not the right one.

But, if you are accelerating, and lugging momentarily, do you get out of the high gas use region faster and with less fuel than if you downshift, then upshift again?

- Jack

Jack, I'll try to explain to the best of my ability about all of your questions.

Here's the second part.

Thank you Cody. Your explanation of the huge range in A/F ratios for a diesel was a real eye-opener. I had no idea there was such variance. I DID think there was a difference in burn rate though.

And, I knew lean gassers burned hot, which is what is damaging. I did not know that rich diesels burn hot. Yes, I can see that lugging causes a rich mixture, given what you describe. Why the heck does a rich diesel mixture run hot when a rich gas mixture doesn't?

And, isn't "lugging" a "heavy" load for both? Couldn't the A/F ratio for a diesel be adjusted for this condition to keep from being too rich?

I totally resonate with this statement: "Only controlled experimentation will tell. In my position, driveability reins over economy....mostly because people in my neck of the woods USE their trucks." I hope you did not think I was suggesting some kind of tune that made the truck marginal to drive. I certainly do not have that kind of tune in my truck and would not want one.

As I've said in many other posts, I seem to pass all the other RV's and trucks whenever I take my truck and trailer up over the high mountain passes in Colorado.

I still have trouble equating "Vigo" with you! :hehe:

- Jack

Cody, great explanation.
a simple version is that the throttle in a gasser controls how much air gets into the engine. In a diesel the throttle controls how much fuel gets into the engine.

as for why lean gas engines run hot. the gasoline vapor like water absorbs the heat in the cylinder from the previous combustion cycle much faster than air does think of a water mist spray in front of a fan on a hot day. So a lean engine puts less fuel in the engine and thus absorbs less heat from the cylinders and so the engine runs hotter...

Back on topic, I have not even had a chance to play with my AE or Speed tracer other than to connect it to put in the enhancement code... I need to get gauges in and also reseal the front axle and upgrade the brake caliper pins as they are sticking, new brake pads and fix the ESOF got all the parts sitting on the bench now just need a weekend or two of decent weather to do the work... then I can start playing with the tunes.
One thing I want to change on the shifting is when its on cruise at say 40mph and it goes to accelerate to maintain speed the rpms jump from like 1500 to 2100 then starts to speed up. so i am thinking of just locking up the TC in 3rd gear.
I saw there is a setting for Cruise Control Accel Edit its rate not speed and there is also an accel offset. not sure what that does but i might try changing the rate from 2mph to 1mph and see if that lightens up the throttle response to maintain speed speed and mine says 2mph so I think that means it will allow 2mph drop below set speed before accelerating to maintain speed.. Does anyone know which setting(s) controls how much throttle % it will use initially or maximum to try and maintain the set cruise speed? if i could lower the % of throttle response in the Cruise Control it would probably help reduce the rpm surge and the 3-2 downshifting.....
I love cruise control and use it all the time thats why it annoys me so much when its constantly surging and slowing to stay at the set speed

Thanks, southpaw, I didn't know a diesel throttle controlled fuel, instead of air. But I knew about additional fuel cooling the engine in a gasser - oh well, I'll try to not take this off topic again.

Regarding cruise control, which I use too. I disliked the way my truck's TC would unlock and lock back up on mild hills to maintain speed too. In fact, quite a while back, I think I started a thread on this.

But, I've found that by reducing ALL the upshift/downshift and TC lock/unlock speeds to the max in the Custom Options menu on my Gryphon, I've just about eliminated this "twitchy" behavior. Now it seems to just add throttle without unlocking the TC under "mild" demand. When the TC DOES unlock on a hill climb, it seems to be a more "natural" thing - the steepness of the hill feels like it demands it. And, there seems to be less "lag" between the speed control reacting to changed conditions than there used to be. Before, there would always be a noticeable dropoff in speed (about 2 mph) before the throttle increased and there was always a pretty big "overrun" at the top of the hill where the speed would increase 3-4 mph above the setting before the throttle would back off.

So, I think you are on to something with your thoughts about the TC and maybe % throttle.

I should add, though, if I'm towing the trailer, I'm right back to the same "overreactive" behavior when the speed control is engaged. The added weight and drag clearly causes a more abrupt/pronounced slowdown and the throttle demand must be pushed over to the point where the TC unlocks.

So, if it were possible, I'd try to move the TC unlock point up higher in the % throttle/speed curve. There really does seem to be enough power available without unlocking the TC so quickly.

- Jack

That's why i have a chip and not a programmer ...6 shift on the fly choices :)
I see there is a setting for "switch to manually locking converter" its an on or off.. Anyone know how it works? which gears will it lock and unlock and which overrides does it respond to... I am guessing it was put there for a diagnostic aid for tranny problems...

I am waiting on the Fuel sipper tune to try it with cruise and see if it is any different.. most of the other tunes use very similar shift points but are slightly different from the stock points. I would guess there is more difference in the non-PMT1 PCM

Turn it on, burn it, and try it. You'll love it.

Not.

It does exactly what it says it does. It turns the TCC solenoid on while that program is selected. Hey, on second thought, make two programs that are similar, but have one with the test switch at "0" and the next one with "1". You won't have to worry about TC unlocks at inopportune times.

Hey Cody
I think I figured out how to change the OD and other gear minimum speeds see attached image in parameters expert level
http://dygytalworld.ehost-services13...&pictureid=325

:thumbs up yellow:

DJ,

I think that has to do with the PCM being able to test whether or not the transmission actually shifted by way of the ISS and OSS. I wish the factory PCM calibration would perform a 1-2 shift at 15 MPH.....instead of 9.

If I'm wrong, please correct me. Try it!

yep just downloaded a screen capture utility so that i can post screenshots easily...
I will try it once I get gauges etc installed and my front axle overhauled.. priorities :doh: Hopefully Ill get the other tunes from Bill today... Are you up and running with your Minotaur yet? did you get your MDF's.. Do you have a PSD or just tuning for your business... I just think its funny that you are the GM expert and still running Fords :fordbanner:

I have to get to work somehow. :D

Ignorance is bliss in this case. I have seen the SAME failures and the SAME terrible designs for a decade now. Has GM done anything to fix these shortcomings? No. Therefore I drive a Ford.

I've been up and running with it for a couple months now. It's just that Bill had run into issues when trying to change the definition files for a fellow Sniper tuner that was used to seeing tables in a different way...the way Sniper has them set up. I've been working with Sniper for nearly a year now, but overcame the different table layout and the "metric way" and "right way" pressure and temperature differences.


So I've only been able to work with PMT1 and TDE1 in Minotaur for a while...but that's ok because I have thousands of dollars of Sniper tuning software sitting here too and a whole helluva lot of almost useless definition files from them. My Sniper stuff is used for manual transmission trucks at this point.




I have had a couple powerstrokes. I still have one.

Ok Bill suggested I look at the Inferred Throttle Position map in regards to the Cruise control being to aggressive and also said there are some gain options which ill have to try and figure out myself will also try the cruise accel rate setting modification
Just got the new tunes onto my chip tonite so need to run those for a while and also run some AE data logging before changing anything... need to reseal the front axle and replace the caliper pins with the upgrade kit and fix oil cooler oil leak etc. so it will be a while before i get to trying out any modifications i make to the tunes