Hey buddy. :)

Is the ability to completely rewrite the shiftpoint determinations for the 4+3 available? This is what I mean, right now the '87 program is like this when it comes to the OD unit.

1st Gear: Throttle >=60% turns OD completely off until 4th gear.
2nd Gear: Kickdown if throttle >=75% & RPM <2500
3rd Gear: Kickdown if throttle >=75% & RPM <2500
4th Gear: Kickdown if throttle >=75% & RPM <2500


There is more to it as you know, but those are the basics.

What I'm looking for is that since the car's powerband will be changing, those #s probably won't be the best after the modifications are done. They are great for stock, but not afterwards. :)

Once the car is done and dyno'd so that we know where the powerband is, are those #s programmable? If the car ends up pulling hard all the way to 6000 RPM, I'd like to be able to stomp on it over 2500 and still get the kickdown so I can use up the other gear.

3rd gear for example brings you to 3720 RPM if you stand on it at 2500 RPM with the OD engaged. Max HP is at 4200, so it brings you right into the power (hp-wise) band. So this works out good because anything over 2500 drops you too high in the RPM band for HP, but will because of the non-kickdown stay with OD engaged and brings you into the 2900 RPM zone which is max Torque.

Have I confused everyone yet? :) To sum it up....can those #s be changed?

 

I have never checked into those, in the past I have never been able to tweak the 4+3 settings, but it must be able to be done. If I can find a local 4+3 car to play with here, it would help. I'll check into it and email you....

 

No need to devote your time to it, I was just wondering if you knew off the top of your head. :) I can control it manually if need be.... well actually, you can't shift out of OD via the button if you are at 4100+ RPM.

 

I went looking for these in T Cat a little while back. Unless I'm partially blind, I didn't find them.

If you find them, please drop me the info as well.
I'll Email Tuner, maybe they can look into it????

 

This is some info I received from RED86:

Here is the section of the calibration where it all happens. These
values are from the '86 4+3 calibration "BUB".

The comments referring to manual transmission need to be re-done, big
time - OD is disabled in 1st gear for starters. To make sense of it,
any place where TCC is referred to, that is the OD being locked and
unlocked. Skip past the misc settings to the first table. This is the
%load where OD kicks out. in 2nd and 3rd gear. The next table is %load
where OD kicks back in. Note the table is all zeros - OD does not come
back in 2nd and 3rd gears until commanded by the switch. The last two
tables control OD in 4th gear - self explanatory.

I have been trying to figure out how to make the OD default off. Mine
comes on at 122 degrees like clockwork, and usually when I'm pulling
hard to merge into traffic. Looks like that default is hard coded
somewhere around $E17A. The second value below sets the temp where OD
comes on and can be used to disable it altogether.


;*************************************** **************
;TRANSMISSION CONTROL DATA & PARAM's
;ECM TYPE 0x32
;700R4

;*************************************** **************
LC284: .db 0xFF ; SPEED FILTER COEF, (0.996)
; CALIB = ARG * 256
;
LC285: .db 0x78 ; 50C, (122F), COOL TRESH FOR LOCK/UP
SHFT ENAB
; CALIB = (ARG+40) * 256/192
;
LC286: .db 0x64 ; 1st GEAR DIRECT N/V RATIO
LC287: .db 0x41 ; 1st GEAR O.D. N/V RATIO
;
LC288: .db 0x1F ; MIN 4th GEAR N/V RATIO
LC289: .db 0x2C ; MAX 4th GEAR N/V RATIO
;
LC28A: .db 0x05 ; 0.8 SEC, 4TH GEAR N/V TIMER
; CALIB = ARG * 10, (8/10 SEC)
;
LC28B: .db 0x66 ; LOOK AHEAD 1ST GEAR TPS, (100%)
;
LC28C: .db 0x00 ; UP SHIFT/LOCK DELAY
; CALIB = ARG * 10, (SEC)
;
LC28D: .db 0x0C ; 1ST GEAR DELAY TIMER
; CALIB = ARG * 10, (SEC)
;
LC28E: .db 0x00 ; HYST FOR %TCC
; CALIB = ARG * 2.56
;
LC28F: .db 0x00 ; RD SPEED COAST, (32 MPH)
;
LC290: .db 0x00 ; LOW MPH COAST TPS = 3.125%
; CALIB = ARG * 2.56, (TPS %)
;
LC291: .db 0x00 ; HI MPH COAST TPS
; CALIB = ARG * 10, (TPS %)
;
LC292: .db 0xA0 ; KICK DN PREVENT (SHFTER SW)
; CALIB = ARG / 25, (6375 RPM)
;
LC293: .db 0x58 ; KICK DN/UNLOCK TPS
; CALIB = ARG/25, (3200 RPM)
;
LC294: .db 0x74 ; KICK DN/UNLOCK TPS PREV'NT RPM
; CALIB = ARG/25, (3200 RPM)
;
LC295: .db 0x67 ; MIN VSS, (60 MPH) FOR FORCE UPSHIFT
;
LC296: .db 0x00 ; 0 SEC'S, HI TO LO GEAR LOCK
; CALIB = ARG * 10, (SEC'S)
;
LC297: .db 0x00 ; BIAS TO LOCK ENAB THRESH, (26 MPH)
;
LC298: .db 0x23 ; NO PASSBY L/U IF TPS < 99.6%
; CALIB = ARG * 2.56
;
LC299: .db 0x28 ; NO PASS BY L/U IF =< 28 MPH
;
; PASS BY RPH HYST PAIR
;
LC29A: .db 0x32 ; NO PASS BY L/U IF > 800 RPM
LC29B: .db 0xFF ; NO PASS BY L/U IF RPM < 6375
; CAL = ARG/25
;
LC29C: .dw 0xFFFF ; 819 SEC DLY PRIOR TO PASSBY/LOCKUP
; CALIB = ARG * 80
;
???????????????????????????????????????? ????????????
LC29E: .dw 0x00F0 ; KEEP TCC LK'ED UP FOR PASSBY 30 SEC
; CAL = ARG * 80
;

;======================================= ===============
; MANUAL * 1ST GEAR DNSHFT
; AUTO TRANS * NON 4TH GEAR UNLOCK
;
; % OF FULL LOAD * 2.56
; 12 ENTRIES

;*************************************** ***************
LC2A0: .db 0x03 ; 3 MPH, UNLOCK 1ST(MAN), LO GR (AUTO)
;
; %FULL LD MPH

;*************************************** ***************
LC2A1: .db 0x05 ; 23 12
.db 0x15 ; 28 20
.db 0x2C ; 35 28
.db 0x43 ; 50 36
.db 0x58 ; 65 44
.db 0x68 ; 85 52
.db 0x78 ; 92 60
.db 0x7F ; 100 68
.db 0x80 ; 100 76
.db 0x80 ; 100 84
.db 0x80 ; 100 92
.db 0x80 ; 100 100
;

;======================================= ===============
; Manual * 1st gear Up shift
; Auto Trans * Non 4th Gear lock
;
; % Of Full Load * 2.56

;*************************************** ***************
LC2AD: .db 0x09 ; UNLOCK AT 15 MPH 1ST MAN & LOW GRS
MAN
;
; %FULL LD MPH

;*************************************** ***************
LC2AE: .db 0x00 ; 20 12
.db 0x00 ; 23 20
.db 0x00 ; 26 28
.db 0x00 ; 34 36
.db 0x00 ; 45 44
.db 0x00 ; 65 52
.db 0x00 ; 82 60
.db 0x00 ; 82 68
.db 0x00 ; 82 76
.db 0x00 ; 82 84
.db 0x00 ; 82 92
.db 0x00 ; 82 100
;

;======================================= ===============
; MANUAL * 1ST GEAR DNSHIFT
; AUTO TRANS * 4TH GEAR UNLOCK
;
; % OF FULL LOAD * 2.56

;*************************************** ***************
LC2BA: .db 0x03 ; Unlock 14 MPH Hi gr Auto & Non 1st
Man
;
; %FULL LD MPH

;*************************************** ***************
LC2BB: .db 0xC0 ; 100 12
.db 0xC0 ; 44 20
.db 0xC0 ; 55 28
.db 0xC0 ; 67 36
.db 0xC0 ; 78 44
.db 0xC0 ; 88 52
.db 0xC0 ; 100 60
.db 0xC0 ; 100 68
.db 0xC3 ; 100 76
.db 0xCF ; 100 84
.db 0xDC ; 100 92
.db 0xE6 ; 100 100
;

;======================================= ===============
; MANUAL * 4TH GEAR UP SHIFT
; AUTO TRANS * 4TH GEAR LOCK
;
; TBLE VAL = PCT FULL LD * 256/100)

;*************************************** **************
LC2C7: .db 0x1A ; 15 MPH MIN LK HI GEAR AUTO & NON 1ST
MAN
;
; %FULL LD MPH

;*************************************** ***************
LC2C8: .db 0x00 ; 0 12
.db 0x40 ; 30 20
.db 0x40 ; 41 28
.db 0x40 ; 53 36
.db 0x4A ; 68 44
.db 0x4F ; 84 52
.db 0x57 ;100 60
.db 0x5F ;100 68
.db 0x69 ;100 76
.db 0x71 ;100 84
.db 0x78 ;100 92
.db 0x80 ;100 100
;

 

I got that info too! I'm going to check into it. The only thing, I wonder if the addresses are different from $32 to $32b?

Maybe send that info to Tunercat and see what they can do?

I'd love to be able to get that info in tunercat instead of manually changing those values!

Scorp: Looks like it can be done, but it'll take some messing with!

 

One other thing I have always wondered.... maybe some values that are in there for TCC lockup on a 700R4 are shared with the O/D on a 4+3?

I guess they would have two seperate address ranges for the different tranny types, but I can see GM just using the same tables for both tranny types, just putting the expected values in there for the application.

 

I think that is what RED86 was saying..... The Auto and Manual share the same tables.

What I was wondering was the OD operation is different from 86 to 87 and beyond. I forget the specific's. I believe there should be a engagment temp difference. I think the wiring is the same on an 86, (but different onthe 85).

I copied TCat the info.

 

What I got from TCat:

In manual transmission cars, the TCC parameters are
used to control the OD so you should be able to use
these parameters to make the changes you want.

 

That's what I thought, but I tried messing with the settings on an '85 chip once and couldn't get it to control the o/d on the 4+3..... maybe I was messing with the wrong part. It's hard to figure out when I don't actually have a 4+3 car to test on! I just mailed a few chips to a guy and had him try them all out, and they didn't seem to do anything different than stock.

 

Scorp: You must have access to programmer by now, right?

Think you could program a couple chips to test it out? I could send you a couple files.

 

SloRVette has the stuff, but I don't. How much would it cost me? I'd be more than willing to fool around with this stuff.:)

 

Scorp you hang-in w/ hand puppets these day's? :jester

There is some free software out there, but I like Tuner Cat. The support is pretty good. http://www.tunercat.com

Check his links for the hardware. Many like the pocket programmer. It is the cheapest out there. A few have had probs w/ them,... PC platforms, prog modes,... I have the needham unit, no probs. Spare chips, couple $.
It was just a few hundred to get going. People waste more on Corvette this and that, like that $50 TB airfoil. :eek: Wow, feel the power! But hey, you make the big $ right? :)

 

Scorp:

I bought a custom chip from another CF'er that's a 'Kim Baker special' chip. Aside from being a nice improvement in performance, it turned the auto-O/D off on my '86/4+3. It's fully manual now. I'm quite happy.

If you start playing around with read & writing chips, I'll bring mine down if you're interested. You can read it (I'd like a tunercat file of it), and compare it with your '87 chip - you should be able to determine how it's done. I think fully manual is better than the computer determining shift points.

 

gh86e,

I'd be interested in getting ahold of that chip! Would it be possible to send it my way to read? Email me... cmarcho@hotmail.com

I'll send you a copy of the bin to play with.

 

I really don't want to take a chance on mailing it anywhere. It's a one-time thing that came my way. I'll take it within driving distance if someone has a PROM reader. I want to compare the contents with my orig. '86 chip, but don't want to spend money on a programmer - I'm quite happy with this chip, and don't want to make any changes. Also, if it has a copyright on it, I don't want to send the entire contents to anyone. But I'll make note of some of the changes.

This is how the chip was described to me:
"I'm friends with Frank Yunes, owner of A/O Engineering. He developed and
markets "Forced Air Induction" It's a through the front plate induction
system.
Frank had Kim Baker Racing (Corvettes) involved in Forced Air development,
and I asked if Baker could do a "his secrets" chip for me. This is not an off
the shelf chip. It has an aggressive timing and fuel curve. I was surprised
at the increase in power I felt after installing it.
It's for an early 86 4+3, Open air cleaner cover w/ KN filter, ported plenum,
air foil, free flowing exhaust, low temp fan switch, and 160 thermostat.
Initial timing stays at factory spec.
It also eliminates the automatic overdrive engagement, giving you the control
to engage/disengage overdrive at will."

I have a 180 degree thermo, and 185 degree fan switch. Engine runs great. Sounds it too with Power Effects wide open :)

 

that's cool, I can understand that! If you do get a bin, I'd appreciate an email of it!


I was thinking, what they may have done to disable the o/d function is to set the temp to enable it really high. It's the TCC lockup temp.... probably changed it from 122d to 300d or some high number like that.

I've always tried to change the point that the o/d kicks in, not cut it out altogether. But changing the temp that it's enabled by the ecm may do the trick. Then the driver can control it with the switch. Would that work?