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?

John
84 300SD
82 380 SEL
86 230E

On my 230E it located on the drivers side just forward and to the right of the fuse boxes. It's smaller than you think, thats what made me miss it several times;) The plug should only be adjusted if you got a severe case of bad gas (no pun intended ;))

Check this thread also...
http://www.peachparts.com/shopforum/tech-help/15467-ezl.html

yal Thanx for the response.
John