A friend who is a keen drag racer was telling me yesterday that if you put normal unleaded in a golf, therefore assuming Octy is same, that the ECU retards the timing to suit BUT doesnt reset when super unleaded is then used, this isnt what I thought, any comments?:confused:

It will reset but will take a bit of time before the adaptive settings are at optimum.

Its what knock sensors are for.

Yea it does take a bit of time to do it. My Octy had never seen SUL untill i got it then after about 100miles i could feel the difference

My car lost some of its 'urge' for a week or two a couple of months ago. I assume that the timing had been backed off and put it down to some dodgy petrol, it did return to normal again (-ignition timing changes make the engine sound different too). I used Shell Optimax, now V-Power, or Tesco 99.

Incidentally, driving to Cornwall and back (on mostly V-Power and a splash of Tesco 95.... :( ) seems to have cleaned the engine out nicely and economy has improved quite a lot

My car lost some of its 'urge' for a week or two a couple of months ago. I assume that the timing had been backed off and put it down to some dodgy petrol, it did return to normal again (-ignition timing changes make the engine sound different too). I used Shell Optimax, now V-Power, or Tesco 99.

Incidentally, driving to Cornwall and back (on mostly V-Power and a splash of Tesco 95.... :( ) seems to have cleaned the engine out nicely and economy has improved quite a lot

I always saw an increase in performance and economy after a good long drive / blast down the motorway.

Must admit though i never use anything but Optimax / V-Power or BP Ultimate.

Yeah, I've noticed exactly the same - stick to the premium.

I'm sure I've read somewhere that on some cars you can manually reset the sensor, so that it will search for the best setting straight away, instead of taking a running average.

Can this be done on a VAG vehicle?

yea but i think it has to be done via VAGCOM on DBW cars

If you reset the learned map it has nothing to start with but its base settings. So it takes the same amount of drive cycles as it would anyway to adapt again.