My daughter has a 86 230E. Its a Euro 300E with the 2.3 engine. It has developed a spark knock. Moving the distributor does not have any effect on the timing. I was told that the 2.3 has an EZL ignition with a trimming plug. A round black plug with the letters KAT or EZL written on it. This is supposed to adjust the timing for different fuel octanes by giving a reference resistance. You adjust it by pulling the plug and turning it to the next number. Any comments? Where is this plug located?
82 380 SEL