B8 S4 ZF8 Swap

Very limited information on this swap or the feasibility of it for that matter is available. I am going to share what I have found, what I'm working with and the hurdles I'm anticipating if this is followed through with.

This is involved with A4 Avant swap that I am working on and the path will reflect that. The idea I'm working with is swapping over the engine and necessary hardware and adapting it to the transmission that is in place.

So as far as the wiring goes there are two paths to take.

- Path one - Pick up a wiring harness from a 3.0t Q5 or SQ5.
- Path two - unpin transmission plug from 2.0t harness and repin into 3.0t harness

Path two is less expensive and is the more likely path in this scenario.

The DL501 and the ZF8 are nearly identical in their wiring.

There are 4 Wires shared with the ECU and TCU on the DSG. Two are bus wires. One wire goes to the main body harness and one is a direct connection (Throttle control is my theory).

ZF8 has 3 wires. The two bus wires and the one that goes to the same pin in the main body harness.

So wiring wise, it looks like they are similarly setup with the ZF8 being simpler on the grounds of being less concerned with rev matching.

My real concern is coding.

Here is the S4 Engine/Trans coding


Here is the A4 Engine/Trans coding


Now here are some pictures of what I was looking at in VCDS on the S4's engine module that sparked the idea for this.




When I tried changing the coding it was not accepted.

Alright, so here are my questions.

- Do these coding options show up on any engine module for this generation of A4/S4?
- Would changing this coding be as simple as having the security code for the module and recoding it?
- Is all of this possible through VCDS?
- Is it possible through ODIS?
- Would a dealer even be willing to take on a coding change like this?

I know that the TCU has component protection and I would consider that a minor problem relative to getting coding to work.

This will generally be a question of what the software the ECU or TCU (as well as other modules) are compatible with. Just because coding bits exist and are documented does not mean the software in the module supports that functionality.

A bit of history: Prior to MY2000, just about every ECU could be coded between manual and automatic. But starting with the advent of CAN networking in MY2000, VAG started using software that was specific to the type of transmission in some (but not all) ECUs. Those ECUs still had coding bits (or configurations) for the transmissions they didn't support, but would reject them every time. The only way to use the other type of transmission was to reflash a different software into them that supported the desired transmission type.

I suspect (but do not know for a fact) that you'll be looking at the same sort of headaches here.

-Uwe-