Looking for help getting started on a custom conversion

[pashford]

I have a custom conversion with a 383 SBC, TPI, drive-by-wire and a 4L80E controlled by an LS1B (OS 12221588). The problem is that the OS works with a 4L60E, and not my 4L80E. I haven't been able to find a tune based on the 12221588 that has a 4L80E, so I expect I'll have to completely reflash this controller to a new OS (I hope that doesn't change the pinout).

As the current OS is a 512KB PCM Flash, I assume that limits me to the smaller flashes.

So, this generates a couple of questions. First, given that I'm limited to 512KB flashes, there are 35 tune files on TuneFileDepot.com that appear to be able to fit in the PCM. How do I identify the files that do drive-by-wire?

Second, would I be better off getting a 1MB PCM? Does that extra memory allow the firmware to be "smarter" about what it does? How do I identify this PCM at a junk yard?

TIA.

[Taz]

OS 12221588 was used by some 2002 Corvettes (and carried over into the 2003 model year) - so I will assume your DBW setup is using a Corvette TAC Module and APP (accelerator pedal).

Some 2002 Corvettes used the more common 12212156 OS - which was also used by many 2002 trucks equipped with the 4L80 transmission.

So ..... it appears that you need a 2002 Corvette tune from an automatic car, using OS 12212156. Then you should have no problem swapping in the transmission segments from a 2002 4L80 truck.

[joecar]

I don't know sufficiently about DBW compatibility, but...

+1 on what Taz said:
Corvette 12212156 auto trans (4L60E) file with transmission segment swapped from a truck 12212156 4L80E file

( 12212156 is typically a 2002 OS )


or you could do this (second method):
modify your transmission sub-harness to allow the 4L60E segment to operate the 4L80E controls
(invert 2-3 shift solenoid signal using relay, drive TCC PWM from TCC on/off signal, remove 3-2 control signal).


The advantage of the second method is that the 4L60E segment keeps the TCC locked on closed throttle until the mph falls below the TCC release curve

( all truck 4L60E/4L80E segments unlock the TCC on closed throttle regardless of mph being above/below the TCC release curve )

[pashford]

OS 12221588 was used by some 2002 Corvettes (and carried over into the 2003 model year) - so I will assume your DBW setup is using a Corvette TAC Module and APP (accelerator pedal).
My wiring harness is based on a 2003 'vette. I have a 'vette TAC and a Caddy APP (cost savings).


Some 2002 Corvettes used the more common 12212156 OS - which was also used by many 2002 trucks equipped with the 4L80 transmission.
OK. I found a truck tune file that has the same base OS, and a 4L80E transmission. Would there be any issues just flashing that entire tune into the computer? My engine's breathing is VERY different from either the LS1 or the LQ4, so I would expect similar amounts of tuning to be required. Am I missing something?


So ..... it appears that you need a 2002 Corvette tune from an automatic car, using OS 12212156. Then you should have no problem swapping in the transmission segments from a 2002 4L80 truck.
Subject to the answer to the question above, I think this is a plan, IF OS 12212156 can handle drive-by-wire. Is there any way I can verify this?


Corvette 12212156 auto trans (4L60E) file with transmission segment swapped from a truck 12212156 4L80E file

( 12212156 is typically a 2002 OS )

or you could do this (second method):
modify your transmission sub-harness to allow the 4L60E segment to operate the 4L80E controls
(invert 2-3 shift solenoid signal using relay, drive TCC PWM from TCC on/off signal, remove 3-2 control signal).

The advantage of the second method is that the 4L60E segment keeps the TCC locked on closed throttle until the mph falls below the TCC release curve

( all truck 4L60E/4L80E segments unlock the TCC on closed throttle regardless of mph being above/below the TCC release curve )
Good information. I think I'll try the truck 4L80E segment first, but it's nice to know I've got another option.

[Taz]

Your best bet (least headaches) is to use a Corvette tune as the basis for whichever direction you go with the transmission options. The Corvette TAC Module you have is different than the TAC Module that was used with trucks.

[ScarabEpic22]

There's something up here, in the first post the OP says he's using a 512kb LS1B PCM yet he says the OS is a 2003 Vette...doesnt add up. All OSs 03-07 are 1MB, cant flash one into a 512kb PCM.

I agree with Taz, use that Vette base OS and seg swap the 80E trans/trans diag in OR just rewire the pins (might suggest this to keep the TCC locked on 0% TPS).

[Taz]

Hi Erik,

The 2003 Corvette calibrations were a carry over from 2002 ... these are an exception to the 512 Kb / 1 Mb PCM general year of use rule.


Cheers,
Taz

[pashford]

Your best bet (least headaches) is to use a Corvette tune as the basis for whichever direction you go with the transmission options. The Corvette TAC Module you have is different than the TAC Module that was used with trucks.
OK. I'll go that route.

I'm still wondering about support for the TAC. Is there a way to find this out, or is it built into all of these PCMs?

[ScarabEpic22]

Hi Erik,

The 2003 Corvette calibrations were a carry over from 2002 ... these are an exception to the 512 Kb / 1 Mb PCM general year of use rule.


Cheers,
Taz

Interesting, good to know Taz.

[pashford]

just rewire the pins (might suggest this to keep the TCC locked on 0% TPS).
What would this get me, aside from having to add another relay to the harness?

[EagleMark]

The advantage of the second method is that the 4L60E segment keeps the TCC locked on closed throttle until the mph falls below the TCC release curve

( all truck 4L60E/4L80E segments unlock the TCC on closed throttle regardless of mph being above/below the TCC release curve ) and keeping your OS...