GWW

Been searching and reading on TCC control with my 6E running an AUJM bin. I wanted to turn my lock off while driving around town and leave it to work on the freeway. All of the reading and studying led me to belive that modifying these four constants were the way to go. I'm using Tuner Pro RT by the way.

Low speed low gear unlock to lock was 28
Low speed low gear lock to unlock was 26
Low speed high gear unlock to lock was 38
Low speed high gear lock to unlock was 36.

There are four other constants for high speed low and high gear same as above that all came set to 255 by GM essentially turning them off.

I accomplished what I set out to do by setting low gear low speed to lock at 58 and unlock at 56. I set low speed high gear lock and unlock to 255. Crazy thing is this is contrary to what I first thought and still makes me wonder what I'm looking at.

Originally I set low gear low speed (thinking this meant third gear)to 255 wanting to turn it off. I set low speed high gear (4th I thought) to 58 and 56. When I drove the car the TCC did not lock at all. So I thought what do they mean by low and high gear? I swapped the constants as stated above and it worked!

Any clues what is low and what is high? Is it more to do with the numerical ratio of the transmission? I.E. 4th is a lower number than 3rd. Obviously I'm happy with my results so I'm not going to change it but I'm trying to understand the logic-these things keep me awake at night....

RBob

iTrader: (1)

High gear is 4th (overdrive), low gear is 2 & 3 (can't lock in 1st).

What you are seeing, that the tables appear to be reversed, can be caused by several items. The hac may be incorrect, the XDF may be incorrect, or, the 4th gear switch in the transmission doesn't match the calibration option bit.

I would start with the 4th gear switch option. Can usually test this by using a calibration parameter that is based on a 3-4 or 4-3 shift.

In the $6E hac it has this parameter:

I would set it higher, at least 2 seconds for the test. Then see if the TCC relocks immediately or after a delay. Do this at lower speeds in manual 3rd. If the delay occurs then the 4th gear switch isn't set correctly.

If no delay then the XDF is labeled incorrectly.

Of course this also depends upon the hac being correct about the re-lock delay being for 4th.

RBob.

GWW

I reset my low gear low speed lock from unlock to 28mph. This is the ARAP constant located at 2B0 according to my XDF. Low gear low speed lock to unlock is now 27mph and located at 2B2.
Low speed high gear unlock to lock is back to 35mph at 2CC.
Lock to unlock is 33mph at 2CE.

My TCC delay before lock in high gear is at 2AC and now set to 3 seconds.


I drove the car in man D 3rd at slightly above 28 mph-no lock. Still in third I accelerated to just slightly above 35 mph and it locked. I don't think it should have-hmmm. I think it should have locked at 28 because I was in 3rd and ignored the 4th gear constant. While holding 37-38 mph I lifted and began coasting, the converter released. I stepped back into the throttle and the lock occured after 3 seconds.

Drove the car in 4th, no lock at 28 mph, locked at 35 mph, coast release same results and behavior as above.

Went to 2AB which is labeled delay before lock in low gear it was at 0.300 seconds. I set it to 3 seconds, set the lock delay in high gear back to 0.200 seconds and drove again.

GWW

Next test drive.
In 3rd still locks at 35, unlock after coast, step back in 35 mph seems to lock up immediatly.
No lock at 28 or unlock at 27 in 3rd.
4th gear locks at 28 unlocks and locks it seemed immediatly.

GWW

I've changed the header in my XDF so that low gear and high mph titles are now swapped and reset back to the mph and behavior I wanted. It seems to me the tables are swapped in the XDF, HAC, and Bin. I've left the delay at 3 seconds in low and .2 in high. I want to see what switch it is using now.

By the way all of this started because the TCC bucks constantly at cruise. I'm trying to get rid of that but one thing at a time first.
Any other thoughts?
Thanks

JP86SS

iTrader: (1)

Being mainly an SD guy, The first thging I saw when I loaded the 6E definition to try and help you is that the tables were for TPS% at a MPH.
So what you are desribing is somewhat the same as the $8D (SD) tables.
The MPH is preset in the table by the definition and the TPS load controls when it will lock or unlock.
You would need to be greater than the lower table to lock and less than the other to unlock. (or vive-versa, I'm tired and not thinking well)
That's just my initial thought when looking at the definition.
Be sure you are working with the correct thing or your thoughts could decieve you.
$0.02

GWW

I may have found something. I will know tonight after I burn another chip and test.
The car has a new automatic in it, along with converter. I read my Helms manual and there are multiples of 700R4 models available during 1989. Some had N.O. 4th gear pressure switches and others had N.C. switches. I still have my original transmission so I pulled the pan on it and the one in my car. I removed the internal wiring harness and solenoid from both and layed them out on my bench.
The new trans has a color coded orange solenoid with N.O. 4th gear pressure switch and N.O. temp switch in series.
The old trans has a color coded light brown solenoied and N.C. 4th gear pressure switch, no temp switch.
Verified this with the Helms wiring diagrams.
I swapped everything out.
Remember the problem I have is that to get my TCC to lock at 58 MPH I have to adjust low gear settings even though I'm in fourth. My computer is reading the opposite constant that it should. I'm thinking that is because it's looking for a normally closed switch not an open. My thoughts were without changing my bin put the original switch etc back in and drive it. If the problem is now corrected the car should not lock at freeway speeds or in town because my low gear constant is the only one I'm using and it's set to 58. Well I drove and sure as heck no lock.....
Tonight I'm going to burn a chip with the constants in high set to 58 and low to 255. If I'm right my 3rd gear should be low-no lock and 4th high-lock at 58.
I'm excited...!

1MeanZ

iTrader: (9)

this is great info. well written and easy to follow. You are tackling one of the biggest weaknesses in these cars in stock form. I HATED my automatic had I have known about chip burning back then I probably could have fixed it. Thanks.

RBob

iTrader: (1)

GWW, changing out the trans wiring harness & 4th gear switch to the correct one is the best way to go. There is also an option switch in the calibration for the type of switch. If I am correct it is at location $14 and is bit 2 ($04).

The hac has it marked to select an analog MAF. If you get a chance try flipping that bit and see if the TCC tables reverse roles. Then change it back. It would just be nice to know if that option bit is the correct one.

1meanZ, I know exactly what you are talking about. I too have wondered why the stock TCC tables are set up the way they are on some f-body's. I think it comes down to meeting CAFE along with federal noise regs. Great driveability gains are to be had by changing the lock/unlock tables.

RBob.

GWW

I can most definitely confirm that my transmission had the wrong 4th gear switch. The computer is accessing the correct tables now. I found another post where the builder of this transmission states he uses N.O switches in his rebuilds. I found out the hard way.
I tried the MAF switch but I didn't get to confirm it very well. I checked the box. I placed the car in third and the converter didn't lock until it reached the limit set by the 4th gear constant. Looked good so far. Would have liked to try it a few times but, then.... the car quit running while idling. I couldn't get it to start, if it did run, it ran like the MAF was disconnected stumbled stuttered and quit. I burned a bunch a chips, with the box unchecked like it should be, still the same problem. I changed computer, chips, even plugged in a stock memcal and then started over with a fresh bin. I got it running again but I'm a bit scared of it now. I don't think I'm gonna play with that again. Still not sure I haven't hurt something like the MAF or a relay.
Thing is possessed I swear it is.
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Should I post this as a seperate topic? I want to stop the bucking and need help.
Thanks everyone

RBob

iTrader: (1)

I have no doubt that the 4th gear switch was incorrect for your vehicle. I didn't realize that there was a tranny swap involved. Otherwise the 4th gear switch would have been the first thing to check (it was mentioned as a possible issue).

For the bucking & stalling. With the engine idling tap of the MAF sensor. If it changes how it runs (stumbles, stalls, etc) the MAF or MAF connector is going bad.

Do the same with the ECM, tapping on it while the engine is running.

RBob.

GWW

Like I said the car is possessed. For some reason the alternator picked the exact time I tested the flag you mention to begin failing. Once temps came up the alt would start to weaken. So maybe I'll check the flag again and let you know.

One more note, now that the ECM has the gear right it is also choosing the correct TPS v.s MPH table.So far, no bucking, but the jury is stll out. I have third set to lock at 38 and 4th set for 58 for now. I found that leaving the TCC unlocked (2600 stall) drove the trans temp to 200d.

It's 104d today and the engine runs too hot with the air on to test anymore until it cools off.

Thanks for help everyone. I felt kind of silly asking what seemed obvious.