Not important, just curious.
 

What are the differences between the S8 AVP and AQH engines.

I could be wrong but I think physically they are the same, it's just different software for different emissions standards resulting in slightly different torque curve.

Yeah thats it as far as I can tell from comparing them. The AQH has Bosch ME7.1 and the AVP has ME 7.1.1. Based on observation, that 0.0.1 difference will cause the EML to come on for faults with secondary air or secondary O2 sensors for an AVP whereas it doesn't on an AQH (logs a fault but no light), and I believe 7.1.1 also has individual control of the cam timing whereas 7.1 just does them both together. There are minor wiring differences for this iirc.

In the A8 the change from ME7.1 (FL1) to ME7.1.1 (FL2) meant a change from EU3 to EU4, however for the S8 (according to the factory documentation) both versions are EU3. Interestingly, in the UK it appears DVLA didn't spot this and so the FL2 S8 is also rated at EU4.

Indeed, that's why my (and other) later models with ME7.1.1 are allowed into London's ULEZ. Not that I'm likely to take the S8 there any time soon......

Thanks for all the replies everyone, much appreciated.

Stay safe.

You guys are lucky!

I requested the homologation document from Audi, it came back with emissions code 1999/102A/EG which turns out to be Euro 3
Even though my car is late 2001 production.