N20SS

iTrader: (5)

Ok guys, here's the deal. I had a new 4l65E built, a new 3600 converter
(had another brand 3600 before) and put a set of 3.89's in. Changed from 3.23's. I have all the transmission tables figured out pretty well except for the TCC. The TCC locks in 3rd, but when I get the 3-4 shift the converter unlocks, so I have an rpm increase instead of decrease after the 3-4 shift, then the converter locks back up and I get a decrease in rpm's. It's doesn't keep locking and unlocking or anything it just won't stay locked during the 3-4 shift. I've even tried setting the TCC to lock in 4th at the same rpm as the 3-4 shift to no avail. Can someone tell me what I'm doing wrong. I'm probably missing something.

rel3rd

iTrader: (43)

How about this parameter?

Personally, I do not want mine locked during shifts.

BTW, dumb question and maybe nothing at all to do with anything, but you did change gear ratio in "Speedo" section, right?

N20SS

iTrader: (5)

I did change the gear ratio under speedo yes. When I think about it, I don't really want it to lock during gear change either, but I've never had an increase in rpm after the 3-4 shift before. I don't get it. It's almost like 4th is a lower gear than 3rd.

I have that parameter disabled. I just checked all my old tunes, and I've always had it disabled. I'm at a loss here. I just don't understand the rpm increase after the 3-4 shift.

rel3rd

iTrader: (43)

Post up a copy of tune. I'm sure someone here with fresh eyes looking at it can find the problem.

jimmyblue

iTrader: (11)

If it was locked in 3rd, and you're shifting well
below the coupling-RPM of the converter, then
this is sort of to be expected.

Different converters with different STRs will
differ in how they couple up at lower RPM. The
lower-STR one ought to hold the RPM down
better, at low RPM shifts but be more "stretchy"
at higher RPM.

I don't lock at all in 3rd so never see this sort of
behavior.

9000th01ss

iTrader: (10)

Disable lockup in third.
Set the 3rd apply speed to 256.

BrianC98Z28

iTrader: (11)

get fool z to change the 2 misfire detection rpm and see where we stand when the smoke clears

N20SS

iTrader: (5)

I could, but I'd really like to keep it in 3rd. Some of the cruises we do are not fast enough to be in 4th so lockup in 3rd would help with trans temps and mileage. I might do away with it if that's my only choice. My last 3600 didn't have this problem though.

9000th01ss

iTrader: (10)

Well it's not 100% clear on what you want. If you want it to stay locked during the shift then change the setting in the pic to 'enable'

If your converter does not have damper springs in the clutch, I would not recommend doing this.

N20SS

iTrader: (5)

I can see where I may have not been real clear. What I want is to retain lockup in 3rd and 4th, but not have an rpm increase when the converter unlocks and the tranny shifts from 3rd to 4th. I don't think I really want the converter locked through the shift.

9000th01ss

iTrader: (10)

It's impossible. You can leave it as is (which I know is annoying as hell), Raise the tcc apply mph to where it'll never apply in 3rd, or wire up a switch that you constantly have to play with while you drive.
Or get a tighter converter.

The problem is the not stock converter.

You can do as you said in the first post and set tcc apply to the same mph as 4th shift but the rpm drop is going to be even more annoying than the problem you have now. Actually if you did that, you'd still see the rpm increase when the 4th shift was commanded and the converter released.

SILVERZZ28

iTrader: (3)

Mine locks in 3rd stays locked through 4th. You will be surprised what you gain if you have the power! I had some local people hating on me because they
thought I was spraying my car

9000th01ss

iTrader: (10)

Depends on your converter and in your case the transmission. With a 4L80E and a converter designed to shift through the gears it's not usually a problem.

If you have a solid TCC with a 4L6xE it can eventually break the input drum if driven hard, like at the track.

Now thinking about it, I've recently put a 3600 converter in my car and tuned it all, the TCC is the biggest pain in the ***.
In all this tuning I noticed if you change the upshift pressure modifiers to a positive number and put a mechanical gauge on the trans, the pressure rises right before, during, and after the shift. More or less depending on what you put in there. Then it returns to normal.

Theoretically if you set it to lock through shifts and put a negative number in the 3-4 upshift modifier it might feel alright. Just not sure what it would do to the 4th gear band since it may slip more.

I'd bet if you screwed around with it enough you could get the low load shift modifiers in the negative and the high load back to normal, especially if the converter is real close to fluid coupling speed at high load, which I doubt you'll ever get it to feel right. Best part is you'd give up trying and learn to live tcc apply with 4th only.

N20SS

iTrader: (5)

Thanks for all the input. I can't modify any of the pressure tables as my tranny is vacuum modulated. It appears though that it wasn't a tuning problem after all. After logging some part throttle driving yesterday, I found that it's not actually going into 4th gear, just commanding it to. I will be pulling the servo to look at the 4 piston in the next few days. Band apply is the main difference between 3rd and 4th, and we suspect a bad oring or something on the servo piston. I'll post back when I see what's going on.