I hear you bluegoat, like you know it happened to me once at the track, but my last trip at the track I was hitting the rev limiter on every gear, i created a thread here: http://www.hptuners.com/forum/showthread.php?t=32769. Made few changes, I even used bluecat's 6lxxxx spreadsheet, so far part throttle shifts work fine, but i haven't test it at WOT.
To test it at WOT, go to the highway and do the 3-4 WOT, if the shift points are set right, she'll give you a clean 3-4 shift.
I didn't even use the calc to set my shift points cause i didn't know we had one until a couple of months ago.
Let her run in every gear using manual mode, and in the logs you'll see speed and mph. then adjust accordingly setting the mph/rpm a little bit lower to let the trans have time to shift. i recently used the calc and the results were pretty close to what i have now. had i known before about the calc to set the initial shift points, and i would've saved days of work logs and tune adjustments at nights :)
I've posted in both G8 forums linking them to this thread. hopefully more G8 people would show up here. Who tuned her, ot what software they used is irrelevant, the trans seems to have a mind of its own on that initial 1/4 mile run after the engine has been shutdown for a cool down, don't know why it affects the 3-4 only, but in all cases, people are finding out the trans shift correctly if the car is hot lapped after the first run, or if a 3-4 shift has been completed, after the engine has been restarted prior to a cool down, and before the 1/4 mile pass has been completed (driving around the track parking area, or doing a burnout in the staging lanes until the trans sees the 3-4). TM is irrelevant as well.
8850 has a vette with the same trans and same problem, hotlap the car and the 3-4 issue goes away.
question is , why ?
Yes, same problem. Sure would like to eliminate the problem before this Friday. If I can get my converter in and 150 break-in miles I'm hopeing for a 10 second pass. It's going to be close but if that 3-4 lag can be solved I feel I will be a .1+ closer to that 10 second time slip!Quote:
Originally Posted by bluegoat06
It IS in the tune. Mine used to do it, now it doesn't.
Where at in the tune ?
Never mind Wreck, This is not a delay in the 3-4 shift like idriveag8 had in the other thread. It seems to me you guys were having delays evertyime for that gear, where you stated somebody else "fixed" it for you.
I thought i was very clear on the issue, but if i wasn't let me repeat it again, i don't have any problems whatsoever with the 3-4 shift unless i stop the engine to allow the car to cool down at the track. What difference does it make for this stupid trans to have a 30 min cool down vs a hot lap ?
Good luck, i'm taking mine to the track on Saturday. will see how she behaves now after the inertia adder change.Quote:
Originally Posted by 8850
My inertia adder table is lower than your screen shot in the higher torque frames. My shift time is already zeroed all the way. Maybe the inertia adder is the key. Let us know how you do.Quote:
Originally Posted by bluegoat06
I was so frustated when i opened up the thread that i forgot to post the tune :)
So here it is what i'll give a try this coming Saturday.
The only difference in the trans compared to my last track visit in January is the Inertia torque profile 3-4 and the inertia adders 3-4, plus some little things i did to the shift pressures everywhere, but that was just more to change the shift feel.
I'll let you know how it goes.
Mine doesn't have issues that way either. I always try to let it cool.Quote:
Originally Posted by bluegoat06
Can you post your tune or screen shots of the fix?Quote:
Originally Posted by wreckwriter
No I can't because its a commercial tune. I don't know what part of it was the fix, only that after this last tune the issue was gone.
Check the grr8 site in the tuning section
Simple example from somebody using a remote tune solution : http://forum.grrrr8.net/showthread.php?t=22492
And like him there are many on the Grr8 site, different tuners, different tuning solutions, same problem
Check the G8board, last pages from the 1/4 mile section. different tuners, different tuning solutions, same problem, same temporal fix in either case (hotlap or 3-4 parth throttle shift),
Most people won't or can't recognize the problem until they hotlap the car and feel the difference. i'm not saying this is your case. i'm speaking for myself and all the other fellas i meet at the track that doesn't even have a tune, or have tuned their vehicles themselves or have custom dyno tunes. tuned or not, the issue is there.
To be honest, you're either really lucky, or the supercharger is masking the actual issue :) either case, good for you, i'm not exactly a 6l80e tuning guru, but i doubt is a configurable parameter we can change, and i really think it's more of another one of those hidden parameters that we have no access to.
A few months back, TM was either on or off, now we can control the upshift TM to pretty much what we want, and the downshift almost to a point.
a couple of months back, we didn't have spark TM retard, now we do,
a couple of months back we couldn't prevent an aftermarket verter from slipping in full at part throttle., now we can ...
My tune is also posted, you can see is not a disable all TM switches, lower the trans shift times to single digits, and increase all pressure by 60% type of deal. like i said, i'm not a 6l80e trans guru, but i'm not a complete newbie when it comes to this trans.
I'm surprised that nobody else have had a saying on this. I thought we were here to help each other out :(
I think the problem is that nobody knows how to fix our 3-4 inconsistent shift. I have not tried what Waker has suggested but your tune appears to have the changes already that he suggested to no avail. Guess we will just have to keep experimenting.Quote:
Originally Posted by bluegoat06
Had a similar problem with my 08 Vette the one and only time I went to the track a few weeks back. I'm planning on going today if I can get finished work. I'll report back if I have anything new to add.
Went back to the track yesterday and had the same problem. Won't be going back until it is resolved. Just hoping I did not already damage the trans.
Hopefully if it's tuning we will have it solved soon.Quote:
Originally Posted by BlkLS3
Although my shift times were somewhat slower stock, I don't remember having this probelm with stock tuning. Only took it to the track one time stock but I wonder if the shorter shift times we are usinig have something to do with this problem.
I've already changed the 3-4 shift times back to stock. everything from the 3-4 base upshift for normal mode and sport, 3-4 inertia profile and 3-4 torque adders for both, Normal and Sport, this was the suggestion of a senior tuner in one of the G8 forums.
I'll have to wait more time to give it a test since i couldn't make it to the track this Saturday. The advice was that the shift times for the 3-4 shift were too short and that if i took the 3-4 shift times back to stock, the problem was more likely to go away. i tested the 3-4 on the highway tonight several times and as always the 3-4 was clean.
So will see how she behaves on the track in a couple of weeks.
finally glad to see somebody else have the same problem i have asked around and could not get anything but people lookin at me like i'm crazy.
i thought it was only at the track 3 / 4 shift. if i drive my car lets say stop at
gas station start it back up and hammer on down the street, it will fall on its
face between every shift once. pisses me off because i have raced 12.50 and faster, cars on the street and beat them but at the track the fastest i have been able to produce is 12.87 @ 109.87