Bigger Throttle Body...Tranny not shifting right

The tranny doesent shift right under wot anymore...it shifts just not right...went from the stock 69mm on my 99gtp to a 78mm aftermarket. When at wot and some pt the tranny feels almost like it slipps as it is trying to shift and then it is followed by a hard jerk when it actually switches gears.


What tables need to be changed? The shift ''time'' tables hyave already been set to 0.006 to make the shifts quicker...but that is how it was set before. and it was working fine...so i am almost certain it has nothing to do with this table.

Did you do a throttle position relearn after installing the new TB?

nope didnt know that i could....tell me how please?


thanks a bunch

Here is a scan of it happining...look at the 1-2 shift compared to the 2-3 shift at wot...about mid way through the scan. the 1-2 takes way longer.



Dont mind the kr i am working on the o2's still

anyone??? look at the 1-2 shift compared to the 3-4 on the atached scan....SOMEONE PLEASE HELP!!!

Quote:

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Originally Posted by TDCRacing

nope didnt know that i could....tell me how please?


thanks a bunch

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KO = Key on to engine run position... NOT start.
KOFF = KEY OFF position.

ENGINE NEVER TURNS ON, ok?
***********************

Press pedal to floor, KO for 10 seconds, KOFF
Release pedal, KO for 10 seconds, KOFF

Repeat the process 3 times.

The results are not instant, but over 3-4 engine restarts, your idle will start to come down, if this is the issue.

BTW, the install of a larger TB never did anything to my tranny shifting characteristics. Not sure why it would now? Maybe a really "off" MAF table?

Looked at the scan, could not load the tranny parameters for the tranny shift times, it told me "not available"?

Just by the scan (thats not a good indicator, though), I see nothing wrong. What are you expecting? A shift time from the 2-3 as fast as the 1-2? What are the shift times set for in your bin?

Idle is not the problem....just the shifting...All i am expecting is that the shifts stay like they were....and the 1-2 before was more like the 2-3 that is in the scan.


Shift time is set at 0.006 across the board


Maybe it is slipping on the 1-2 shift and i just don't realize it...I mean that is a pretty good power increase from before with the mods i put on.Something just doesent seem right though....



Like i said i will go wot it will start to shift (taking longer than normal) then at the very end there will be a jerk (the jerk feels like it did before the mods when it shifted with the increased pressure settings in the tranny tables...just at a more delayed time now)



I will dig up a wot scan before the mods in a little while to show you the differences in the shifts that i am talking about.

Well maf was way off....still seems like it is doing it though...let me fix this before i go on to something else...On the 1-2 shift i am hitting the rev-limiter for a very brief second on wot runs. It causes my injectors to cut out.before i wasent now i am...i dont know why. Any way,under wot >rpm it is set at 5600....now under wot >shift speed it was set at 48 at first...i moved it down a few mph and it was still hitting the rev-limiter on the 1-2 shift...any ideas? move it down even more? I understand both Conditions have to be met (shift speed and rpm) so it seems like that should have worked.

anyone??

I would increase the rev limiter (or you could try decreasing WOT RPM by 100) and disable anything that disables injectors. Next compare the shift settings to stock and multiply the difference by 0.5 or go back to stock numbers. Test to see if it still happens.

When you are doing this scan to adjust your MAF if it is off allot and make the changes after testing the trans settings or the other way around it you have started this. That way you will only have one group of things changing.

Let us know what the results are. Also post your tune so we can see what every thing is set to and what model and year is your car..

car is a 1999 gtp with the following mods....

ZZP FS Intercooler~ZZP 78mm Billet Throttlebody~Coated Pacesetters~1.9 modified rockers~3.2MPS~#105 springs & retainers~PRJ fuel logs~2.5 off road DP~Ported & Polished S/C~JMB fwi ~Wrapped crossover~160* T-Stat~



I lowered the wot shift speed for the 1-2 shift about 4 mph and also lowered the wot shift rpm to 5500.

I guess i will see if this works later tonight. I was only going over and hitting the rev-limiter by aprox 80 rpm's...but reducing the wot shift speed from 49 to 48 then to 47 didnt make a difference as far as me not hitting the limiter...so it's at 45 now

A well used tranny could easily slip 500-1000 RPM pas shift points. It takes 2 things for a shift to take place... the MPH and RPM settings must be met. After that the shift is commanded. Now... how long the tranny takes for the shift to take place is going to be affected more by tranny condition more than anything else.

I think my tranny is slipping because the mph shift point is set at 44 i belive and the rpm shift is set at 5300 and the other night at the track the rev limiter was hit once....anything that would help this as far as settings go? I already have the line pressure set at 96.

Lower the MPH and/or RPM so it doesn't hit the limiter, that sounds like the most obvious thing to first try before considering tranny mechanical issues.

man im having the same problem after i did that....it takes longer to shift than it did before even when driving with very light throttle. i know it;s not slipping at that low of throttle.


any other suggestions?


I know this may sound funny but im almost 100 percent sure it has to do with the tb or the maf table...i had to insrease the maf table a lot because of the lean condition with the addition of the new tb...could that be it? i dont know how to add fuel under the pe table...or wich table it is...

got the over rev situation fixed....i was lowering the mph down but ended up havin to lower the rpm set point down even further.



Anybody have anything else on the other issue?

double post!! Sorry!

Hello,
I just noticed this post.

I'm working on a car for local GP owner and he has all this stuff done to the car, and he had a simmilliar problem.

This friends GTP has a LS1 TB and it had one sweet spot but the rest of the time it was randomly messed up. I hooked up the scanner and turned on the electrical, not starting the car, just turn on all the electrical and the scanner.
Then I push the throttle pedal and I'm only 50% to the floor and the scanner says its 100%. No wonder it didn't work right.

I bought this thing from ZZP that re-calibrated the TPS sensor signal and now I can tune this car..
Check it out. http://www.zzperformance.com/grand_p...=333&catid=108

The interesting thing is what Jerry said, Can we do some procedure and save the money I just spent on that TAC?
I'm going to try it Jerry...

You know when i first installed it when i would let off of the gas compleatly....it would say 1-2% tps...that went away and it's fine now. my mass air flow table was very very rocky and that seems to be what was causing it.

Quote:

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Originally Posted by TDCRacing

You know when i first installed it when i would let off of the gas compleatly....it would say 1-2% tps...that went away and it's fine now. my mass air flow table was very very rocky and that seems to be what was causing it.

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Hey there, I have the exact same problem that you have here. I mean exact, slipping, hard bang into gear, new throttle body. Now i ask if you were ever able to figure that out or not? Its really tickin' me off, because i got a shift kit assuming that would fix the problem... it didn't. It shifts to 3rd perfectly, and 3/4 throttle 1-2 shift is spot on, but as soon as i give it 100% it slips, then grabs hard and chirps the tires... If you figured it out and can give me some tips i would be at your mercy lol!! Thanks in advance!!!!

When you changed the TB, the air flow changed, that has to be re-calibrated first. The VCM doesn't know that, it is still working on the old parameters. More flow=leaner A/F, since every thing changed when you changed the TB, that would seem to be the first thing to look at IMO.