MikeT 88IROC350

What do these tables actually do? There are constants that dictate what speed the TCC locks/unlocks depending on 4th gear or low gears. But how do these tables come into play? Which takes priority, tables or constants?

I noticed the ARAP bin has values much higher than the stock GM tables. What advantage does this give?

Sorry, but these tables do not make sense to me!!!!

------------------
Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

JPrevost

I'd also like to know. I noticed a HUGE difference when I was driving with the stock91 RS auto chip and went to the anlu (L05 cop car chip). I adjusted the values back to the hypertech and it drives a lot nicer, I think I get better gas milage in the city, not sure about that but the stock L05 chip had some funky numbers down low and the thing felt like it was slipping so how and I'm sure it wasn't the trans.

------------------
, Jon (350 TBI!)
91 Red My website

GregWestphal

iTrader: (1)

The constants are just parameters (guidelines) that determine the lowest speed that the converter will lock up (when accelerating) and stay locked up (when decelerating). The tables determine when to lock up the TCC based on %TPS. The low gear tables are for 2nd and 3rd gears.

I increased my table values since the TCC was unlocking too easily, ie: just pressing down a little on the gas caused it to unlock. I had also increased the mph constant for the low gears since the stock value was 21 mph and the TCC was locking up and unlocking several times just driving out of the community, hence driving me crazy. I then re-installed my TCC lock-up harness that prevents the TCC from locking up in 2nd and 3rd gears since I didn't want it in those gears and doing so hurt my time in the 1/4 mile. I lowered the 4th gear mph constants so that the TCC stayed locked up at lower speeds, which works for me since I switched from 2.73 to 3.42 gears.

------------------
Greg Westphal
'87 IROC 305TPI/A4

P J Moran

I have worked with these, too. I have been running the stock '88 settings. I like them much more than the stock '87 settings. The TC more readily unlocks, now, and I like that. I also "messed around" with them to see what affects various changes had.

It looked to me that %TPS is not the throttle position, but rather the amount of change of throttle position. A higher setting requires more pedal movement, not necessarily a higher throttle position.

I'm not at all sure of this, it's just how it seemed to act to me. This is why I wish I had a hack of the $32B. Only within the context of the code in which such parameters are used can you truly evaluate the effect of making changes.

I am now running on the $6E code (the famous ARAP bin). The values in it's tables are different from the '88, but do look good. I will let you know how I like them.

------------------
'87 IROC 5.7l TPI - original owner!

MikeT 88IROC350

Thanks for your posts. I would like to keep this discussion going. I understand the constants ok, but still a little fuzzy on the tables. I set my constants to 51 lock and 49 unlock, both gears. I think I got this tip from PJ on a previous post. I like these settings much better than the stock numbers, esp since I have 2.77 gears. I can easily notice when it locks in 4th during normal acceleration. But in 3rd, it is harder to noctice when it locks, since the rpm doesn't change much. At lower speeds cruising back roads, the motor doesn't lug around so much, plus I think it is better on the motor to NOT run at such low rpms.

As far as the tables, seems like you would want it to UNLOCK quicker, ie when you nail the gas, to get those rpms up to accelerate. The stock unlock/lock NOT in 4th tables seem to stop at 50% or 45%, whereas the ARAP bin values go up to about 92% for these 2 tables. What is the theory behind this? The IN 4th tables go up to 97-99%, but of course these numbers are at higher speeds.

------------------
Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

GregWestphal

iTrader: (1)

Your lock/unlock numbers are quite high, especially for the lower gears. If you're driving at a steady speed of 40-50 mph, then your TCC isn't locking up at all and that's not good for the tranny (too much slippage and heat). I know that when I had 2.73 gears, my 305 had no problem pulling my IROC quite easily from 40 mph on up with the TCC unlocked. I now have 131k miles on the engine and it still runs fine, not burning oil or leaking anything.

I set them to not unlock quicker because it was unlocking just barely moving the gas pedal from a steady-state cruise. If I get into it more, it'll unlock at around 50% throttle around 40-50 mph, higher %TPS at higher speeds. I'm not sure why the ARAP bin is different although that car probably had 3.27 gears, so it didn't need to unlock the TCC as much since it was revving higher at any given speed compared to your car with 2.77 gears. At the higher speeds, you really don't need the TCC to unlock if you're in 4th gear. Of course, if you floor it, you'll get 2nd or 3rd gear and the TCC will unlock. HTH...

------------------
Greg Westphal
'87 IROC 305TPI/A4

P J Moran

Shortly after I bought my car, I installed a "kit" from B&M that allowed you to prevent TC lockup in the lower (1-3) gears via a switch on the instrument panel. I liked that, and eventually did away with the switch and just permanently disabled lockup in the lower gears. I've been running that way for over a dozen years with absolutely no transmission trouble. Bear in mind that most of my miles are highway, but that's still alot of miles without trouble.

Now that I can do the same thing with the PROM, I am considering "un-doing" the "kit" and restore the factory wiring. By setting the lockup speeds very high and the unlock speeds very low (zero) for the lower gears, the TC never locks up until 4th. The lockup settings for 4th are a matter of preference, as I see it. Mine still has a luggy feeling at 45mph, so I keep the TC unlocked until I'm really "on the highway" (51 mph, for now).

------------------
'87 IROC 5.7l TPI - original owner!

[This message has been edited by P J Moran (edited May 01, 2001).]

[This message has been edited by P J Moran (edited May 01, 2001).]

P J Moran

More observations...

Comparing the stock'88 ($32B) to the '89 ARAP($6E) tables, I found that:

1) All values in the ARAP are higher than the '88
2) In the '88, the unlock values are higher than the lock values.
3) In the ARAP, the unlock values are lower than the lock values.

This really confuses me. I need to get a grip on this. For a given speed, how can the lock value be greater than the unlock value? Wouldn't this prevent the converter from ever unlocking (except when downshifting)?

Perhaps the unlock values are those that have to be exceeded before unlocking (increasing %TPS), whereas the lock values are those below which %TPS must fall (decreasing %TPS)to re-lock. It sorta makes sense this way, but my head's hurting, now

------------------
'87 IROC 5.7l TPI - original owner!

MikeT 88IROC350

Good observations, PJ. I confirmed your observations. I am using the values from my 88 ADS chip for all 4 tables. They seem to be higher than the stock 88 GM, and they seem to increase with speed proportionately. The ARAP bin was a special test bin, so I imagine those values were not designed for economy. Maybe they did not want the TC to unlock, but as you said that wouldn't make sense. I think I will just stick with the table values that I have.

It's interesting that you changed your constants to UNLOCK at 0mph. Did you do that for both "lower gears" and 4th? Maybe I should lower my unlock speeds. I didn't see much of an rpm change in 3rd, when the TC locks, so I could really care if it does!!!
I just don't like lugging the motor on the 5 mile back road to my house, which I cruise at 40-50mph. Most of the time I keep it in 3rd anyways.

I don't think (hope) it would hurt the converter, it doesn't get much above 80 where I live. Remember, the old cars never had at TCC lock up!! Some day I will do some serious tranny work, and a gear (or rear end) change.

P J Moran

More observations:

I burned a (basically ARAP) chip with the '88 unlock values and left the ARAP lock values alone. The TCC still wouldn't let go, no matter what. So, I burned another one with the '88 lock values (now with '88 lock and unlock vlaues). Yep, it works right, now. It unlocks at moderate throttle, but takes even more throttle to downshift. This is just what I want.

This tells me that if the lock values are higher than the unlock values, the TCC won't unlock - except upon downshifting. Apparently, whoever created the ARAP bin didn't want the TCC to unlock.

Bear in mind, this is all with 4th gear only. Again, I have my tranny hard-wired to never lock the clutch in the lower gears, regardless of the PROM image. Applying what I have learned in 4th, it would appear that to prevent the TCC from ever locking up in the lower gears, you would set the unlock values extremely low, and the lock values even lower.

------------------
'87 IROC 5.7l TPI - original owner!

[This message has been edited by P J Moran (edited May 10, 2001).]

[This message has been edited by P J Moran (edited May 10, 2001).]

Desert86Roc

PJ, I too have my trans hard wired to only lock up in 4th. But I also took the ECM out of the equation and have been much happier. My TCC is activated only by a 4th gear switch on the valvebody, and the ground wire actually grounded to the casing (not the ECM). There are advantages to this, that IMO outweigh the disadvantages:

Advantages:
- TCC does not lock in 2nd & 3rd, increasing performance
- TCC only locks in 4th, and does not unlock (better MPG)
- Higher Top Speed atainable (acts like a stick, where TCC does not disengage no matter how much throttle, unless trans drops you to 3rd)
- better city and hiway mpg
- less slippage / heat / wear

Disadvantage:
- car may act jerky like a stick in high gear if there is too much slop in your drivetrain and you are driving slower.

Personally, I have not experienced the disadvantage as I have enough torque to compensate. If for some reason the car doesnt feel like it is accelerating quick enough, you can always put your foot into it so that it drops to 3rd, unlocking the TCC.

------------------
Mike Metzler (Desert86Roc)[*] Webmaster: SpeedWorldMotorplex.com[*] Click Here For 86 IROC 305 TPI (406 build in progress) Page

ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.365 @ 86.785 mph (uncorrected, headers, no NOS)
<><

CanadianBeast

I am confused. Right now I'm running a completly unchanged ARAP bin in my 89 L98. From what your saying it sounds like no matter what I do The TC is locked in fourth. Correct?? This isn't what I want. I would like it to be like PJ's where it will unlock before it shifts into 3rd, but since Idont have the TDF to read older bin files I don't know what the 88 nubers look like. Although all of the 89 bins that I looked at have higher lock numbers than unlock numbers like the arap, so does that mean they won't unlock in 4th.

In adition to all of that I would like to make one bin tha leaves the TC unlocked in 1,2,3. As I stated before I have gotten myself confused and I can't figure out what kind of changes to the tables I need to make to make that happen.

Also how do the constants come into play in all of this?

I gonna keep looking at them, maybe it'll start to make sense.

CanadianBeast

Ok looking at the constant for low gears on my ARAP bin it shows
unlock 16mph lock 31 mph

so does this mean that no matter what if it goes below 16 mph it will unlock and if it goes above 31mph it will lock. correct?? I think so.

Now for the range between 16mph and 31mph it looks to the tables. Is that right?

With these tables, say for example the unlock %tps vs. speed not in fourth, does this mean that say at 36mph if it sees a 14.8% gain in TPS it will unlock the TC. And vice-versa for the lock tables?

As mentioned before I am very confused, but I would like my TC to stay unlocked in the low gears and have lock and unlock in fourth. To do this I figure I need to set the low gear unlock constant very high and the low gear lock constant very low, thus meaning it'll never be over the unlock constant or under the lock constant.

Please reply if I'm way off base base, and sorry for all the questions, but if you teach me now then I can answer then next confused guy and you won't have to.

[This message has been edited by CanadianBeast (edited May 10, 2001).]

P J Moran

As best I can tell, there two sets of controls: the constants and the tables.

The constants work like baseline values - at low TPS values. The tables take over at higher speeds and/or TPS values.

As long as your speed is below the lock constant, the TCC will not lock. When your speed drops (from a higher speed where it is locked) to a value below the unlock constant, the TCC will release.

This is why the unlock value is usually lower than the lock value (constants). I have mine set to L:52 U:49 for 4th and L:64 U:0 for the lower gears. This keeps the TCC from locking until I am into fourth gear and going at least 52mph.

As for the tables, they seem to come into play like downshifts. They allow the TCC to release when you step on the gas. They are what determine how much you have to mash it to cut it loose. If the unlock values are higher than the lock values, once engaged, the TCC won't release until actual gear downshift occurs.

The thing that still puzzles me is the meaning of %TPS. Is that a throttle position, or a change in throttle position? It seems to act like the latter, but the former makes mores sense to me. I'm still trying to figure this stuff out, too.

BTW, here are the values I have in my TCC tables (4th gear only) right now:
LOCK - 0.4 2.0 6.6 14.5 23.8 34.0 46.1 57.8 69.5 80.9 91.0 99.6
UNLOCK - 0.8 4.7 15.6 29.3 44.1 58.6 71.9 85.2 94.9 99.6 99.6 99.6

Feel free to try these.

------------------
'87 IROC 5.7l TPI - original owner!

MikeT 88IROC350

Good post PJ, I knew you would come thru with a good observation. Hopefully this will clear up the Q's on the TCC lockup situation.
I am printing out your posts for future reference.

Right now, I am locking low gears at 50, unlocking at 48. Looks like those numbers are going to change!!

CanadianBeast

Yeah thanks PJ. I was confused! I'm gonna try out these numbers that you posted.

Fromthe looks of it with the numbers you posted lets say youran down the quarter mile.
Through first and probably second the TC would stay unlocked but whenit hit 64mph in third or maybe second, not sure, but wouldn't the TC lock up? Wouldn't it bebetter toset the lock constant for lowgears to some absurd number like 200 mph to ensure that it never locks up in the low gears? It seams to me that if I cruising at 60mph I will be in fourth anyways so why bother have the TC lock up in third?

One more. for the tables, I think I uderstand the unlock ones, if your going a ceratain speed and give it a certain amount of gas (TPS) it will unlock the TC. But what about the lock tables. Is it saying at a certain speed if you let off a certain amount of TPS it'll lock the TC??

CanadianBeast

Mystupidspacebarisn'tworkingright.

P J Moran

Yeah,Ihatewhenthathappens! LOL!

I'm not thinking in terms of quarter mile performance, here -- mostly drivability. However, It would seem that keeping the unlock value very low (zero?) for the lower gears will prevent it from ever locking. Because mine's hard wired to not lock there, It will be awhile before I can test my theory. Go for it!



------------------
'87 IROC 5.7l TPI - original owner!

P J Moran

Here's another followup:

I removed the pressure switch that blocked the computer control over lockup in the lower gears. My theory about setting the constants did not hold up.

I have the lock speed set at 64mph for the lower gears and 52mph for fourth. Now, in 4th the converter won't lock up until 64mph! BTW, lockup in 3rd also occurs at 64mph if I'm still in 3rd at that speed. With the switch in line, it would lock up at 52mph. This, IMO, is a logic error in the code. When in 4th, only the 4th gear values should be referenced. For some reason, the lower gears value is being used (the fact that it's set higher than for 4th has something to do with it). I'll bet that if I drop the lower gears value to something below the 4th gear value, the 4th gear value will once again control lockup when in 4th, but I will get unwanted lockup in 3rd.

I have 4th unlock set at 49mph. That still works. Once I get over 64mph, the TCC locks and won't release until I get below 49mph.

I am coming to the conclusion that the only to prevent TCC lockup (via the PROM) in the lower gears is through the tables. Perhaps setting the %TPS values to near zero will have the desired affect. That will be my next attempt.

------------------
'87 IROC 5.7l TPI - original owner!

P J Moran

A related followup:

I suggested before to set the unlock speed for the lower gears to zero. I have reconsidered that. As far as I can tell, the unlock speed is that at which the TCC lets go when coasting down. Setting it that low keeps it from unlocking until downshift or the %TPS table values release it. I have decided that the unlock value should be relatively high, just a few mph below the lock value. That way, it will release sooner.

Please don't get the impression that I am (or consider myself) an expert on this. It's just the area I'm studying the most right now. I could be totally missing the boat on this, so countering opinions are more than welcome. Take my comments/recommendations with a grain of salt.

------------------
'87 IROC 5.7l TPI - original owner!

P J Moran

It looks like I'm talking to myself, here, but I'll share more discoveries with y'all.

I changed the "TCC %TPS Lock (and Unlock) vs. Speed" tables for the lower gears. I set the Lock values at 0.2 and the Unlock values at 0.1. Those aren't typos. They are intentially very low numbers. I want the TCC to never lockup in 1st thru 3rd. I set my Lock and Unlock speeds (constants) to match those for 4th, just because it seems "right", though this is of little or no consequence.

I made these changes on a $32B PROM and a $6E PROM. In both cases, IT WORKED! No more need for a hard wired pressure switch. I hope some of you find this useful.

Aside from some possible future tweaking of these settings, I am through working on TCC control. Time to figure out Highway Mode...

------------------
'87 IROC 5.7l TPI - original owner!

Glen

Thanks for the effort and the information. I have been following this thread and I intend on using your info. Thanks again!

------------------
Red '85 MPFI V-6 T-5 Sport Coupe (bought new),now an IROC in sheeps clothing.
Rebuilt and installed '88 IROC L-98 TPI,700-R4,3.27 posi/disk rear,instrumentation, steering gear, and all suspension parts (even the wonder bar)
Mods:
IROC wheels, Hi-perf. rebuild on 700-R4,TCI sizzler torque conv.,B&M megashifter, L-98 .030 over,balanced,decked,blueprinted, SR Torquers, KB pistons,9.1:1 CR, port matched stock TPI, comp cams .450/480 206/210 cam, all free mods, subframe connectors, Edelbrock TES/jet hot coated, CATCO cat, Hooker catback, MSD 6A, airfoil, AFPR, K&Ns, polygraphite bushings all around, and modified ARAP bin.

MikeT 88IROC350

I am still following this topic as well. I still don't have a firm grasp on this subject. I think I agree with your logic from above. My TCC also seems to lock up in 3rd gear. I had the lower gears set to lock/unlock at 150/5 mph. I have the 4th gear set to 45/43, and the unlock prevent parameter set at 50. It seems like under normal acceleration with the gear selector in 4th, it won't lock until I get to 50. Sometimes it does lock before 50, hard to tell sometimes when accelerating. Also, once I was just in 3rd gear, and I am quite sure it locked up around 50, or maybe lower. I am beginning to think there is some logic in the EPROM that expects the TCC to lock in 3rd prior to 4th, and it needs a lower speed (than the 4th lock speed) to do so.

All of the factory bins that I have seen show locking the lower gears before the higher gears. I think I will be making some more changes, perhaps looking at those tables again. I am surprised that setting the lock AND unlock tables (low gears) to those LOW values worked. Not so much the actual value, but the fact that you made both unlock and lock so close togethor. Guess I will just have to try it and see.

Good work PJ.

------------------
Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!