I'm considering a transmission swap from A4 to M6.
Mechanical + cabling all clear.
Is there a way to reprogram the PCM using LS1Edit so that it thinks it's a M6?
Or will I have to bring it to a GM agency for a reflash?

Its possible going from A4 to MM6 to use LS1edit and simply turn off the DTCs related to A4, and tweak the tune and get away with it.
You would not be able to go from a MM6 to a A4 and do the same thing

BUT really the correct path is have someone who can do a GM flash, change 1 number in VIN so its seen a same car but with a MM6 and then flash the PCM with a TECH -II for that year/trannie.

Of course then you have to totally tune the new flash for your other mods but now things like the 1 to 4 cags, reverse lockout, how MM6 handles column lock and computes gear ratio is all functional with correct MM6 flash being used.

You will of course need a wiring loom that is for a MM6 rather then the A4 wiring it uses.

MM6 uses a clutch switch so you also need that functional.

In a first time I wanted to keep the A4 program and turn OFF the DTC's. But I don't know what kind of problems are related to this patched-up configuration.

Some kind of limp mode?
Lower timing?
Open loop?
Richer AFR?
....

My actual VIN is 2G2FV32G9W2220630

2 (Country = Canada)
G (Manufacturer = General Motors)
2 (Make = Pontiac)
F (Carline Code = F-Body)
V (Pontiac = Formula, Trans Am)
3 (Body Type = 2 door convertible)
2 (Restraint System = Manual Belt)
G (Engine Code = 5.7L (V8) MFI)
9 (VIN verification)
W( Model Year = 1998)
2 ( Assembly plant = St. Therese)
220630 = Production sequence

When you say "change 1 number in VIN so its seen a same car" you mean increase the production sequence by 1? (= 220631)


Thank you - Stefano

Look at your A4 and there is a VIN Derivative code, then look at the MM6 it also has a code
Replace the last digits with the ones from MM6 in VIN #

This is a valid VIN for a 1998 with a MM6

2G1FP22GXW2129570

All clear!

But... wait a minute: my LS1Edit connector won't read it! I have only one licence
I'll have to reuse the same number or buy another licence.

To have a dealer or someone replace your A4 flash with a MM6 then the Tech - II MUST see a VIN # with a digit saying its a MM6 that is how the tool decides which flash to install.

A gamble but you could email those highway robbers at carputing and ask if they would modify your existing flash file so that is becomes a MM6 F body.

OK I'll give it a try.

About the other question: if I keep the A4 program and turn off all the ralated DTC's will I have some kind of problem? I can copy the settings of another 98 program with an M6 in my standard program. Only the speedo doesn't work at it should.

Right now I don't know if turning off a DTC tells the PCM "ignore it" or "try to work around it without giving a trouble signal".
Hard to explain... I can imagine that the PCM still try to command trans pressure, solenoids and so on: sees no results and try to solve a problem. Will it loose calculation capacity and become slow?

Turning DTCs off does not tell the PCM to ignore the functions, just not to trip the errors.

If you turn off all A4 DTCs and also the trannie A4 tests
the MM6 as to tuning requires little other then making the right changes to idle, timing and torque management.

Simply make your tuning changes then drive the car with a good PCM scanner and see if any other DTCs have to be turned off but a 1998 has fewer DTCs and functions then newer PCMs

Thank you!

Here an idea...

What causes the PCM to know something is bad with the transmission?
Faulty solenoids
faulty thermometer
faulty pressure sensor
....

What if I connect dummies (resistors and / or solenoids) to the A4 wires?
Will the PCM just "think" everything is fine because of the dummies and allow me to use the M6 troublefree?

OK this is a junkyard-mechanic idea, but why not?

Sure there is no reason you cannot measue the devices and see what their resistance is and then replace them with same value resistors but not sure if that neans much difference then turning the DTCs off

Not knowing a Trans am I do not know how much you have to also alter for if it has a column lock, lock for shifter, etc that a MM6 does not have

If still using a A4 PCM flash I would assume it looks to see if signals from shifter lock is there and is in park position so at the least you have to simulate that.

Whereas a MM6 has no shifter lock and only looks to see if clutch switch is open.

There is an helpful thread on another forum about modifying the electric system to make it work.
In reality it's not a clen job because the next owner will have an hard time if he brings the car in a garage.

I asked Carputing about reprogramming: apparently it's possible to load a M6 program keeping the old VIN. I'll post more about that when I'll exactly know how (and if) it really works.

Sure they can change the VIN # long enough to flash with a MM6 base and then just VIN back to real one.

Today I loaded the Carputing M6 program: it works!
Several parameters are now typical of a manual car: idle speed, trans oil temperature totally wrong, no tranny pressure, no commanded pressure...
Then I loaded the program back to the laptop: now it has my original VIN and the original calibration number!
At the end I loaded the A4 program (yes, I still have the automatic tranny) and everything went back to normal.

I don't know if this can be done using every program of the same year, I just know that Carputing did some modification to the program to fit my PCM.

Email me the 2 flashes and I will compare and verify that all MM6 functions are in fact correct

JR