T-56 program

[HottestZ28]

I am going to swap to t-56 and was wondering how long I can go without a tune
Does it only correct my speedo and idle alittle lower?
someone said that a GM dealership can program my car obd1 to t-56. How do I go about this if possible?

[Joe K. 99 Zeee!!]

The dealership could do it, but they'd be my last choice. Go to either pcmforless.com or madz28.com. Both have great reputations and will do what you need for a fraction of the price.

[Z Ya Later]

I believe manual-trans. cars actually idle higher (Craig's idles at 550, mine at 800). Also, yes, the speedo will need to be corrected. A mail-order tune would be a more cost-effective way...and you can get some extra ponies while you're at it if you haven't tuned for your current mods yet

[Injuneer]

Your speedo will barely move above "0" .... the A4 program looks for 40 pulses per rev of the output shaft, the T56 only puts out 17 pulse/rev. At a true 60MPH, your speedo will be indicating 25MPH.

You will also have a constant SES light for all the tranny codes for the missing 4L60E components, and numerous DTC codes set in the PCM.

And as noted above, there is an idle speed difference, although that shouldn't affect anything.