[jhowell371]

Got out my 89 S2 Porsche Service Information manual and basically it says the change was in how fast the spark re-advanced (in.75 degrees increments) after being retarded 3 degrees by the knock sensor. The S model stretched it out over a much wider RPM range thus taking longer to return to normal. This might be one area where an aftermarket chip might be an improvement if it followed the S2 advance curve. I don't know if it will run with the sensor unhooked but you can try. The S2 requires high test fuel so I assume the S does too. Maybe a different brand of gas might help. I don't use off brand gasoline in the S2.