Direct link to Voltage Regulator - mercedessource.com You may be surprised to see what Kent found was the cause of the starting problem he was having on his 1990 190E 2.6. The car would start and then quit. Or it would start and round weak and rough for a minute before coming to live. It would also idle too low during cold startup. The problem turned out to be a simple and inexpensive fix. This would apply to the 190E, 300E, 300CE, 300TE and other gasoline engined Mercedes during that same period.