http://www.peachparts.com/shopforum/showthread.php?threadid=15363&perpage=15&highlight=chip%20upgrade&pagenumber=1
http://www.peachparts.com/shopforum/showthread.php?threadid=4806&highlight=engine+control+module

The attached two links refer to the DTC 19 and rich fuel mixture for an E420 LH-SFI. I need the update for an E320 HFM-SFI.

Mercedes Benz dealer diagnosed my problem as follows:
Function Test W/HHT/ HFM Codes 035 O2 Sensor
Stop/Mixture to lean, 051 Self Adapt too rich, Replace O2 sensor still at Rich stop, Replaced Mass Air still reads flat, Replace over voltage relay, reading still flat, Diag Faulty HFM Control Module $2200.