3-4 shift 6l80E track only...

[04blackgmc]

What have you done to the trans tune to try and fix the 3-4 shift?

lol... havent done anything yet thats why im posting for some ideas lol...

ive looked looked and looked some more over the logs and dont see any major thing sticking out between the 2...

like i said never was a major issue na since i could cross through the traps inbetween 3rd and 4th and no be a issue..
no i need 4th gear since im mph'ing alot more...

NEVER does this on the street...

[bluegoat06]

didnt affect me as much na dueto the lower traps avg 108-109...

now when i need it to go into 4th on n2o due to mph this issue is really hurting my mph and time...i looked at the logs last night and it just hangs around 5900-6050.... the finally shifts..

on the street NOPE... not at all..

i ran 3 dig races this weekend on concrete 0-120.. not a single issue pulls great and shifts right on time no hanging up...i just know if i got it solved it would picked up atleast 1mph and drop ateast .1-.2 off the 1/4...

I'd assume you lowered the shift rpm and shift mph in sport mode because of the Nitrous? your normal mode shift higher at WOT compared to sport ?

I tried something like that and it didn't work, i tried more pressure, didn't work, i tried more TM, didn't work, i tried changing the shift mph and lowering the rpm so the shift was more mph based rather than rpm,(in theory) and it didn't work, i tried making the shifts times slower, it didn't work.

Try this, put back the tip-in tq mgmt/upshift, flare tq mgmt/upshift and torque reduction/speed ctrl termination back to stock. i don't think the first one have anything to do with the issue since it happens at WOT only, and at the track, but i'm not touching that one until i can double check the 3-4 WOT shift at the track at least a couple of times

On my last track visit, i had 8 runs, and the only thing i changed was this 3 settings in desperation, and after that, got two more runs for a total of 10 passes. This last 2 runs were 100% clean.

July 17 is my next track visit so i'll be able to double check and confirm.

[04blackgmc]

I'd assume you lowered the shift rpm and shift mph in sport mode because of the Nitrous? your normal mode shift higher at WOT compared to sport ?

I tried something like that and it didn't work, i tried more pressure, didn't work, i tried more TM, didn't work, i tried changing the shift mph and lowering the rpm so the shift was more mph based rather than rpm,(in theory) and it didn't work, i tried making the shifts times slower, it didn't work.

Try this, put back the tip-in tq mgmt/upshift, flare tq mgmt/upshift and torque reduction/speed ctrl termination back to stock. i don't think the first one have anything to do with the issue since it happens at WOT only, and at the track, but i'm not touching that one until i can double check the 3-4 WOT shift at the track at least a couple of times

On my last track visit, i had 8 runs, and the only thing i changed was this 3 settings in desperation, and after that, got two more runs for a total of 10 passes. This last 2 runs were 100% clean.

July 17 is my next track visit so i'll be able to double check and confirm.

sport is ment for the n20.. thats why the rpm's and speeds are set the way they are

[madvette08]

Try setting anything for the 3-4 shift back to stock and see if that gets better. Just a thought.

[morgan72]

Well I just put in my 3.70 gears and took it to the track today. 3-4 is a bear to dial in. It feels like someone is putting their foot on the brake for a sec before it shift. I did have it shift firm when I lowered the shift points but then it was too low. My 3-4 is happening at about mid-track, so getting into 4th is very critical for me. Before the gears I just held 3rd so I never dealt with this.

It looks like the command for 4th gear happens at the MPH in the tune. At that point PCS2 begins to drop pressure to 0 and then the shift will occur. So my thoughts are, getting that pressure drop to happen quicker and to happen later. Maybe then I can actually dial in the RPM and MPH points that actually correspond to where I want it to happen.

Thoughts???

Oh my car is a 2009 G8 GT
MODS: Cam, headers, exhaust, UDP, 3.70 diff, LSX intake, Vararam. Stock torque converter still.
12.19 @ 116.33

Prior to the gears, LSX intake and headers the car ran 12.37 @ 115.37

I really think the shift is holding me back a tenth and 1-2mph.

[morgan72]

04blackgmc, I just looked at your logs. Here is something that I'm wondering may be missing in our parameters.

Yours is the same as mine when my car shift like yours. From the time 4th gear is commanded vs when the actual shift begins is 1.5 sec. Now when I had the one good shift it was 1.1 sec. My 1-2 and 2-3 are .75 sec. I'm wondering if there is some timer or delay parameter in the tune. On your street log it was only .7 sec from command to actual. To there is the nearly one sec of hang we are feeling.

Also I'm trying to determine the correlation to the different pressure control solenoids.
I've been logging PCS 1-4 and can't seem to get a clear determination on how the tuning affects not only when the solenoid activates but the pressure curves.

I think the next outing I may try manual mode and see if the problem is there.

[C5pilot]

At some point you have to ask yourself why it only happens at the track. What are the differences? Are you running the same size tires for each test? If not, do you change the tire size in your tune at the track?

[bluegoat06]

I thought of revisiting this thread to see if somebody made any progress.

C5pilot, In my case, the very first time i took the car to the track, i was running Nitto 275/45/17's, so i did initially think it was related to the tires being smaller than my stock 245/45/18 tires. 2nd time i took her to the the track, i ran her with the stock 245/45/18's in all 4 courners, same problem. 3rd track visit i ran her with the same tires, without actually even touching the air pressure in them. same problem.

Something else i remember, besides returning the tip-in tq mgmt/upshift, flare tq mgmt/upshift and torque reduction/speed ctrl termination back to stock. is that i also changed the shift mph for the 1-2 and 2-3 shift to be 1mph lower. i didn't touch the 3-4 in that case. i need to retest the changes though, just to make sure i don't have the 3-4 track shift issue anymore. it did it good the last 2 out of 10 runs, just after the changes.

Morgan72, i have my 3-4 set at 102mph, and my car shift at around 106-108mph per the cluster, depending on how bad the delay in the shift is. what's funny though, is that mph seems to increase while rpm hovers around the shift rpm point. Doing this little changes, helped the trans shifting as it should the last 2 times i gave the car a tried, same day, same track, same everything else.

And i'm sure there are more people with this problem, i've seen this in our forums, so it seems something that affect our G8GT's. i don't see anybody around here with other cars and A6 transmissions having the same problem

[morgan72]

well the more I think about it the more inclined I am to just return everything to stock and just adjust the mph for the gears and start from there. I don't know yet. I'm really not happy with how the car is shifting right now, even at part throttle since the gear swap.

I really want to understand the delay from commanded vs actual shift. I see this in all the logs. The indicator will show the next gear about .75 sec before the actual shift engages, but the 3-4 shift is between 1-1.5 sec. This delay is the result of something, just not sure if we even have access to the mechanism that causes that. So the quicker the car gets, or the faster it goes through the gear the greater the error from commanded shift point to actual.

[bluegoat06]

Have you used the A6 calc, you can put the gears, tire size and max rpm, and it would give you starting point where to start to fix your shift points at part throttle and WOT.

It's interesting to note like C5pilot indicated, why we do seem to have this issue on the track, but not on the street, i've even tested the behavior on the street stabing the gas from a stop and going all the way to 4th, can't replicate the rpm hanging/delay issue from the 3-4 shift.

[morgan72]

the shift points at part throttle aren't so bad. The shift feel went to crap though. Not sure why yet.

So I am looking at the GXP and C6 files and notice that their Pattern A Full throttle table is only one column whereas we have a 0 and 100 column. This leads me to believe there is some code difference as well. It seems that even on the stock tuning there was a delay factored into the shift point. The MPH is when the command shift begins. At that point for the next .75 sec, if you log the Pressure control solenoids you will see pressure changes occurring. Then when the actual shift occurs, you will see another change on the solenoids. Now, the goal here is to understand how the tuning affects the pressure change rates and which parameter tells the computer that the shift is now going to happen.

[C5pilot]

2 more thoughts...

Were the TCC lockup tables adjusted with the new gears? Maybe there's a conflict with the TCC locking during a shift???

Tracks are prepped, streets are not. When you hook on the track it may bring more TM in to avoid damage, whereas on the street you're spinning more and it doesn't feel the torque buildup so it lets it ride.

[bluegoat06]

The mph might tell where commanded shift begins, but have you seen how rpm modifies how late that shift actually ends with respect of the mph ? i know that using for instance 5000rpm doesn't really do much, since the shift would begin with mph, and finish whenever this unkwnon parameter tells it to perform the actual shift. but i can get 3 different actual mph when the shift occurs depending on how close the rpm is with respect of the mph.

Ex: not even touching the mph, i can set the rpm to shift at 6000rpm, and i can see the actual shift at 103-104mph in the logs.

Then i can change the rpm to 6100rpm, i can see the shift at 105-106mph.

6200rpm would yield 107-108mph actual shifts.

All of this without modifying the mph, i got it set at 102mph. the shift always begins at around 102mph. but ends later. i don't log PCS's, but i see the timing drop when the actual shift occurs, along with the needle pegging at more or less the rpm, like if it was hitting a rev limiter for that gear, it seems to move along with theshift RPM i set. i know my actual rev limiter is 6500rpm, so it's not hitting the rev limiter at all.

[bluegoat06]

C5pilot, i get the delay spining the tires, or flashing the verter to about 1000rpm with basically no tire spining. and at my power levels, and stock verter, tire spin is very light from a dig unless i launch her straight from the water box, or if i bring my rpm to about 2000 and launch her from there, then 1st gear is uselss, this damn stock verter is really tight, and the car is too heavy to top it off. , i think the stock verter flashes at about 1000-1100rpm or so.

[morgan72]

well here's my plan for now... I can't really go back to stock, because the gears throw that all off, but what I'm doing now is loading in all the CTS-V parameters and then scaling all the shift points by -12% to get it closer to my gear setup. Even though it's a 6L90E, I will assume GM is using the same torque model for shift feel. I'm really glad I didn't install the converter yet, or else I'd probably be really scratching my head. Converter will not go into the car until I get the shifting sorted out.

If anyone gets a chance I'd like to see a log on a stock gear, stock trans tune with all the transmission PIDs to include all 4 PCSs. I'm curious if the stock car exhibits the same .75 sec from commanded to actual on 1-2 and 2-3 as well as a 1sec+ on the 3-4.

[bluegoat06]

I can help with that request. I'll just need some time during this weekend. i can go back to stock tune without any problems. do you have a config file you want me to use ?
The only issue is that i'm still using scanner 2.22 since i have a bug with the new most recent beta, and i can't log anything with that version.

[morgan72]

here is the config file. It's a bit of a mess but gets all the data.

I tried driving around with the CTS-V program and I did not like the shift feel at all, part or full throttle. 1-2 and 2-3 were about 6800-6900 RPM

I then put back my stock trans program and went into intertia adder and cut down the 9 box number to -.1000 I left in all the stock torque management as well except for the speed ctrl termniate. That I set to immediate. The car felt great. It was firm at part throttle, and very unobtrusive at light throttle. At WOT it shifted at about 6300-6400RPM. WOT shift was nice and quick at .2-.3 sec as logged. It kept wheel spin to a minimum as well. So I think I will begin by raising the shift RPM 100 at a time without moving the MPH until I get the shift to where I want it.

Also there was the same .75 sec delay in my setup. So I think there is a parameter that sets this in the code. I can see the pressure solenoid ramp up after the shift call, but when the actual shift happens it jumps to a specific value. So with HP Tuner Engineers I bet we could adjust some of these timing parameters.

[bluegoat06]

Morgan, here you go
Bone stock tune as the car came from the factory vs my most recent tune and logs with your config file, from a dig, all the way to 4th, street runs.

[morgan72]

Bluegoat06 thanks.

Well there seems to be a little shorter elapsed time between commanded shift and actual on you setup. But one thing is for sure, it is by design in the factory tune as well. It also shows the factory tune is not very accurate about the 6000rpm shift point either. I also noticed that time for the 3-4 is way shorter than mine is when it acts up at the track.

I really need to understand better the command pressure on the various solenoids and how they trigger the shift. I'm guessing there is a command to shift by the computer based on MPH. At that point you will see on solenoid either pressure up or bleed down. There is usually a small jump up or down before the bleed off. After the shift begins, you will see the pressure change, but then when the shift completes you will see a jump in the command pressure of either the same or a different solenoid.

This somehow has to be mapped out and correlated to the pressure profiles in the tune. I think the next test is to match the RPM on shift point to match up to the mph.

For example on your 2-3 shift on your current tune it is at 64.0mph. The log shows at 65mph the command is issued. That correlates to 5960 RPM vs the 6200 you are commanding. I'm going to try this out on my car. I want to see if the time from command to actual is affected. If it isn't, there is either a programmed value or a mechanical function of the transmission.

The next step is to take a few different tunes and logs and export the data to a spreadsheet and compare the pressure ramps for the various tunes and see if we can match those differences up in the program itself.

[morgan72]

One other thought. Based on what I'm seeing, it would be safe to say that the quicker the car goes through the gear the further off the shift RPM will be. This reminds me of a similar issue with the 4L60E trans as well. We had to somewhat anticipate where we wanted it to shift. It was so simple with a manual valve body. You push the lever the car shifted. I would love for TUTD to work like that. It may be possible, but we have to identify the cause for the .75 sec delay.