desTRUCKtive

Ok guys the when I am cruising down the highway at a cruising speed my torque converter will unlock as soon as I decrease the load on the engine. I mean any minimal decrease will unlock it. It will even unlock sometimes when i go over a hill . The question is I need to get rid of this. I am not having a misfire problem and all my settings in Hp tuners are set not to read any misfire.

The thing that I am thinking is TCC max line pressure and min. My max is set at 99 but my min seem low. I have read where people will set there min line pressure to 97 or so. is this good and also do they change the entire table to just one value. Right know I have values as low as 23. Here are some values of what my min table looks like, each segment corresponds to a row (first segment is at 32 degrees F):

77.00125 65.00137 57.00247 50.00152 46.00055 42.00262 39.00265 37.00064 35.00168 32.00171 31.00070 29.99969 25.00076 23.00180 23.00180 23.00180 23.00180

75.00229 63.00241 55.00046 48.00256 44.00159 40.00061 37.00064 35.00168 32.99966 29.99969 29.00174 28.00073 25.00076 23.00180 23.00180 23.00180 23.00180

73.00332 61.00039 53.00149 46.00055 42.00262 38.00165 35.00168 32.99966 31.00070 28.00073 26.99972 26.00177 23.99975 23.00180 23.00180 23.00180 23.00180

72.00232 60.00244 52.00049 45.00259 41.00162 37.00064 34.00067 32.00171 29.99969 26.99972 26.00177 25.00076 23.00180 23.00180 23.00180 23.00180 23.00180

72.00232 60.00244 52.00049 45.00259 41.00162 37.00064 34.00067 32.00171 29.99969 26.99972 26.00177 25.00076 23.00180 23.00180 23.00180 23.00180 23.00180

jus1975

How do you know if your TC is not locking? What does it feel like?

dewmanshu

iTrader: (4)

i am definitely not that great on this topic, buuuuut...what does your TCC Apply/Release Speed vs TPS vs Gear-Normal look like? Is this on auto pilot? Did this all of a sudden start happening? Change anything recently? Get a new tune? Always been a problem?

I posed that same question awhile back...yeh those numbers are supposed to be that low. Pretty weird eh? You have a built trans? Shift kit? My duty cycle has the same #'s.

Wilde Racing

iTrader: (26)

Setting the min duty cycle wont help keep the converter locked, that table controls how much oil goes to the converter. (I'm told)

The table you need to play with is TCC Apply/Release Speed vs. TPS vs. Gear (Normal, Hot Cruise, and Performance)


Also make sure your "Release table TPS" isn't causing it to unlock.

dewmanshu

iTrader: (4)

exactly wilde...but I hate to advise people to play with anything in their tune if the problem all of a sudden pops up. That is almost always mechanical. (not that his is) Put a pic of your apply/release table up desTRUCKtive.

hog

A locked TCC will react like a manual transmission. For instance, when you roll on the throttle the rpms WONT go up with direct correlation. Whn the TCC is unlocked when you roll on the throttle, the rpms will rise quickly directly with the pedal movement.

the 88-99 OBS trucks TCC apply/release is linked to teh brake pedal. While keeping steady pressure on teh gas with your right foot, lightly holt the brake paedal with your left foot just hard enough to illumintate teh brakelights, noy enough to actually slow the vehicle. As soon as you tiuch the brakes, the TCC will unlock and the revs will jump 100-200 rpm. If at this point you roll the throttle up and down, the tach will raise and lower with the gas.
When you release the brake, while still holding the accelerator steady, the TCC will lock and the rpms will become fixed to road speed and not throttle position.
This test will work for some of the older NBS trucks, in my 1997 I used to hold the brake pedal slightly at the dragstrip to keep the TCC from locking at WOT above 85 mph. Not havingthe TCC lock at WOT was worth 1 -2 tenths in the 1/4 mile. Any PCM tuner can remove a WOT TCCC lock, this will NOT affect part throttle TCC apply/release.

Whenever the throttle is released a TCC unlock will occur. GM tuned it this way to avoid engine braking when decelerating.

desTRUCKtive, if the truck was OK before and suddenly started to do this, then something is wrong and needs to be fixed, but if this problem has existed since new, you need to adjust the TCC release speed.

peace
Hog

Wilde Racing

iTrader: (26)

I guess I miss that. I agree, no tuning is going to fix a mechanical problem

desTRUCKtive

Thanks for the reply guys. This is what happened in Chronoligical order. When I first did my tranny swap and TC it was acting the same way that it is right now. I however did change and lower the TC apply and release settings. and it seemed to be locking ok. Then one day I noticed that my speedo was off and I looked under the gear ratio and I was running 4.11 but I have 3.73. I corrected that but then after that my TC starting acting like that again. unlocking when the load decreases on the engine. The tranny is an 80E and not built but it does have a shift kit with a 3200 stall.

The reason why I ask about those tables is that they do control the amount of fluid that goes into the TC. But I was reading on LS1tuning that you need enough pressure to hold the TC locked. But I am not sure if that is correct. Oh and the TPS is set at 100%. I guess I can decrease the values on the release just a little more. Here is the table:

desTRUCKtive

Now that I think about it what do the release values really mean: Does it mean that if I exceed that value (speed on that TPS range) it will unlock. or does it mean that it if I am under that speed it will unlock. The way I am understanding is if I come under that speed it will unlock. HMMM I am more confused that ever.

dewmanshu

iTrader: (4)

you are flipped flopped on the cruising(very little TPS%) TPS% on the apply(lock)

your 3rd apply is set at 30MPH/6.25% and the 4th apply is set higher 36MPH/6.25% same with 12.5% and 18.75%. Most tables I have viewed show the lower gear apply speed higher than the next "up" gear speed. Try changing your 3rd gear apply's to 35MPH and the 4th apply's to...saaay 34MPH or 32MPH.

Now for the rest...here is what I have learned in my lurking...

Many like to disable TCC Lockup completely except for in 4th gear at 40 mph, but for gas saving drivability this "formula"..errrr "setup" seems to work pretty good. Set lock up points 1 MPH higher then the next up shift. For example say 3rd apply is at 40 then make the upshift (4th apply) lock mph setting at 39(in that same TPS% column). This supposedly ensures that the TCC will not be trying to lock during the next upshift(You can turn that off as well with the shift lock button). Now, for release of the TCC, set it at about 5 MPH lower then the apply speed or 3-4 mph higher then the downshift speed, buuut not following the same rule as I just mentioned...3rd release should be a lower MPH than 4th release MPH (in the same column).

(take a deep breath....) Yeh confusing, there are many opinions on this, and alot of different combo's that work great...each vehicle is very different and need to be handled differently. I still stare at these tables with a WTF do I do again feeling. It's more of a test it out thing. Speed Density tuning ain't got **** on tcc/shift tuning...you could play with those settings 2 to 3 weekends in a row!