[Lorenfb]

"I have had a very thorough email from SW on the subject and and am now content to run the car at position 0." - RG5 -

Or until it pings because of; poor gas, hot weather, or heavy engine loads!

If a DME ECM has been set to retard the timing using the internal rotary switch
because of a performance chip or prior to its installation to reduce pinging
or NOx (which was it's purpose), then the net effect on the timing and the
potential engine responsiveness is basically ZERO!

Using that switch in its timing retard modes is the same as grounding pin 10 on
the U.S. DME ECMs. Those that disconnect the pin 10 jumper feel an increase
in engine responsiveness which appears to be similar to the resulting ignition advance
the result of a performance chip. Many who disconnect the jumper during a chip
installation attribute the responsiveness change to only the performance chip
timing advance.

Furthermore, the early 3.2 DME ECMs (prior to '88) had a less responsive chip
which results in more noticeable effects with the additional ignition advance.
Responsiveness always occurs (to a point) when the timing is advanced on ANY engine.
As with ANY change in engine parameters, e.g. ignition advance, compression ratio,
engine temp, or engine load, there's always a tradeoff, e.g. pinging and/or NOx,
or the engine's margin of safety without engine mods, e.g. twin plugs, or knock
sensors.