Help w/ strange TC/Shift issue with Fuel Sipper tune

[soutthpaw]

I have ran the fuel sipper for a couple days now and its good except it does a strange shift hunting thing at light throttle around 40MPH it shfits up/down/up/down a few times... esp when cruise control is set.. I looked at the up and down shift points in FUNCTIONS and they are way lower than the range it is shifting at... does it with warm and cold tranny... Is there another map or parameter I should look at to adjust. I thought it was a 3-4 4-3 shift issue but I briefly had a chanve to run the AE on it and it looks like the TC is locking and unlocking repeatedly and can't settle on where it wants to be(while its in OD). I notice the 100HP tune has a similar shift curve but slightly higher (about 6mph) so I'm gonna try and see if it still does it using cruise in the 100HP tune...
is the 3-4/4-3 shift with (cruise) labeled like that specific for tuning the cruise control shift points??? it seems logical but I already found out that doesn't mean its correct I really need some time without my kids in the truck to run the AE software as well to see what its really doing... so I can see the throttle position when it does these shifts/ TC lock/unlock... I don't recall the 80HP having that issue though I replaced the 80m spot with the FS tune...
It also seems to lock the TC kind of hard like someone has a tow strap attached and giving it a tug when the TC locks. I can't seem to find what parameter is different from the 80 HP tune so not sure what to try changing

[cleatus12r]

Since Bill is away, you can email me the file and I'll take a look at it if you'd like. cleatus12r@yahoo.com

Not saying I can definitely fix it...but I have the weekend to myself and can live tune.

[cleatus12r]

Actually, I see that Bill is on at the moment. Maybe he's got a better idea.

[soutthpaw]

I sent you a PM. Hopefully I can get a chance tonite to find a flat open road and get some AE datalogs. I did one but didnt get all the data I needed
weird is that calculated torque does not work with AE. it works on the Genisys.. Also with cruise it does not display actual throttle pedal position
you will see in the tune that the 4th gear TC lockup is at 4MPH but the 80HP tune is at 42mph I think it was... if its supposed to be always locked why is it unlocking and relocking at 40 mph? The only thing I can think of is that it thinks its about to downshift?
EDIT: I totally missed your email address in the above post will send ya the file

[Power Hungry]

What is the RPM when the converter locks? There are functions that designate a minimum RPM for converter to be engaged. It may be that you're dropping below the minimum RPM for converter engagement but above the MPH point for converter engagement.

Having fun yet? No you see the crazy stuff we have to deal with all the time!

I'll try to locate the specific function that controls it and let you know. Right now, that computer is packed in the back of the Expy and I can't get to it.

Take care.

[soutthpaw]

The RPM was one I didn't get recorded the way i set up AE so that's one reason I need to run it again. first time I used the datalogging function... also need to do it without using cruise so I can get pedal position.... I figured there has to be some sort of modifier to the base setting
Oh and I am in Heaven now defined as "when both my kids are down for their nap at the same time"

[cleatus12r]

Originally Posted by soutthpaw

I have ran the fuel sipper for a couple days now and its good except it does a strange shift hunting thing at light throttle around 40MPH it shfits up/down/up/down a few times... esp when cruise control is set.. I looked at the up and down shift points in FUNCTIONS and they are way lower than the range it is shifting at... does it with warm and cold tranny... Is there another map or parameter I should look at to adjust. I thought it was a 3-4 4-3 shift issue but I briefly had a chanve to run the AE on it and it looks like the TC is locking and unlocking repeatedly and can't settle on where it wants to be(while its in OD). I notice the 100HP tune has a similar shift curve but slightly higher (about 6mph) so I'm gonna try and see if it still does it using cruise in the 100HP tune...
is the 3-4/4-3 shift with (cruise) labeled like that specific for tuning the cruise control shift points??? it seems logical but I already found out that doesn't mean its correct I really need some time without my kids in the truck to run the AE software as well to see what its really doing... so I can see the throttle position when it does these shifts/ TC lock/unlock... I don't recall the 80HP having that issue though I replaced the 80m spot with the FS tune...
It also seems to lock the TC kind of hard like someone has a tow strap attached and giving it a tug when the TC locks. I can't seem to find what parameter is different from the 80 HP tune so not sure what to try changing

DJ,

I'm going to run this tune first thing in the morning. I have spent a while looking at it. I assume you changed the tire size to 601 Rev/mile to lower the PCM's perceived road speed. In addition, you should NEVER have a condition when you're in 4th gear and the torque converter is unlocked unless the PCM is in cold transmission mode. The PCM will command a 4-3 downshift and subsequent TC unlock/relock (and the faster that happens, the better).

Your TC lockup points are unchanged...while the upshift speeds are lowered 2-4 MPH. This might be an issue....and it's going to be exaggerated with different vehicles, elevation, and state of tune.

Your TC harsh lockup is caused by a higher-than-stock lockup duty cycle. Remember, we have a PWM TCC solenoid...the higher the duty cycle during lockup, the more it becomes like an on/off solenoid. The second issue is the torque table...I feel it's a little high in the low load section of the table. The higher the torque table values, the harder EVERYTHING is going to apply. It's just a personal preference of mine to lower the values in the torque reduction during shifts as well. I see that most folks like to run 100% torque during shifts. I prefer about 62-75%.....I call it my tranny saver. I command a quick, firm shift but I never feel it happen.


I'll drive around tomorrow and see what I can see.

A couple suggestions...lower the torque table values in the lower loads by 100-150 ft. lbs. or so.

Lower the TCC lockup duty cycle back to near stock....maybe just slightly higher.

Run a slightly different change in each of your 6 positions and find the one that works the best.


I'll let you know what I come up with on the shifting/TCC issue you're having.

You do know how to quickly copy and paste table data from one project to another don't you? It's a lifesaver while loading stock data back to a modified table.

[soutthpaw]

We are thinking along the same lines.. I am wondering if the altitude is an issue as I am at 6000ft

I changed the tire size based off the BFG chart for my larger tires 315/85r16 maybe ill change it back to the stock 653 on one position and see if that changes anything... if it does then Ill try changing the shift points by the same 8.7%
I was thinking about the torque but shouldn't be an issue at light throttle right?

How does the rpm for anticipated and non-anticipated shifts work? Like I said in another post I am not well versed in transmissions.. I did not have a chance to go run the AE today... I think if i can identify the exact rpm and throttle position TCC status, MPH it will help a lot in fixing it... its basically Bills stock FS file... so its weird that it only seems to do it in that setting though I know he said that the shift points are lowered compared to most of the other tunes... that is why I was thinking its a shift point issue...

I gotta do the front axle and brake overhaul tmw. so not sure if Ill get to play with it... depends on how much time the other stuff takes.

[cleatus12r]

DJ,

I went out and drove it today. First off.....wow. I'm glad that everyone is entitled to their opinion. It's not a bad program, but it's definitely not for me.


Anyway, I was able to duplicate what I think you are feeling....it did it once for me.

Without knowing exactly what to expect and when to expect it, my first instinct is that as the 4-3 downshift is occuring, the torque converter is unlocking. That's normal. The bump you feel after that is the TC locking back up for 3rd gear since you're still at a road speed that allows TC lockup in 3rd.....but just barely. I think it happened at 37 MPH (indicated) up a small incline, low load, and slowly losing speed. It did "double bump" so to speak.

What needs to happen here? Either the 4-3 shift needs to occur earlier (higher speed), later (lower speed), the TC apply rate needs to be slowed down to take away from the "jerk" feel, or the TC relock time after the 4-3 downshift needs to be eliminated.

Raising the 4-3 downshift speed would allow the transmission to downshift before the engine gets to 1200 RPM and help by not transferring as much torque during the downshift. Lowering the downshift speed would allow a 4-3 downshift without an attempt to relock the torque converter in 3rd.

I would do a combination of a few things. I would change the relock time after 4-3 downshift to something rediculously low like .13 seconds. This will get rid of the perceived "flare" and then jerk on relock. I would also raise the 4-3 downshift speed by a couple MPH.....it's not really doing you any favors having it unlock at 37 MPH. You're also right about the harsh TCC apply. Since it's a file meant for economy, it's not meant to be "hogged on" and therefore very low APP is usually used. I'd lower the TCC apply duty cycle a bit in the lower load ranges too.

[cleatus12r]

DJ,

This is a derailment....

I liked the Fountain area a lot. I've ridden my bike (crotch rocket) from Colorado Springs to Fountain a couple of times. It's one of the sweetest rides at moderate speed (when traffic allows). It compares to Wolf Creek Canyon near Helena here in Montana.....only CO has more traffic.

Beautiful country.

I couldn't imagine a 7500+ lb. Excursion with 3.73 gears, 35 inch tires, and these really early shifts at 6000 ft. I had a hell of a time one year I went to Colorado Springs in my 95 PSD. I was only running 35 inch tires, 4.10 gears, and a Big Hoss chip and that thing was a TURD.....even though it was better than average here at 4000 ft. Having no air is a real handicap. Sea level would ROCK.