Last year or so, somebody reached out to me looking for the D-jet manual for the M110.
This version of the M110 book should have that section...
https://www.ebay.com/itm/1979-1980-Mercedes-Benz-280E-280CE-280SE-2-8L-M110-Engine-Service-Repair-Manual/373249993468
I would confirm that by asking the seller to see if it includes section 7.4.
-CTH