I just purchased a VERY clean 1979 300SD with 314k miles. It runs beautiful, interior and exterior is amazing. It needed a few things here and there the I'm currently working on. This is my 4th OM617 Benz. So I know many of the quirks and issues here and there with cars when they get up there in miles.

When I begin accelerating, it starts in 2nd gear. No matter how hard I press the accelerator it starts in second gear. I've read many inconsistent posts that people post about this issue and someone replies that the car was made that way and then someone else chimes in saying that no Mercedes was made to start off in second gear etc. So whether it should do it or not, I have no idea. If I manually put the car in L and floor it. The car gets totally confused between 1st and 2nd gear and free revs in between. Is there any adjustment for this issue? I know my transmission is different from all of the w123 and w126 cars and is a 722.120.

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2022 Nissan Frontier Pro4x
1990 Mercedes 420SEL
1950 Packard 8

Previous German cars-
2001 Mercedes SL500
1983 Mercedes 300SD
2011 BMW 328i (manual)
2008 BMW 535xi (manual)
2006 BMW M3 (manual)
1980 Mercedes 300TD
2006 BMW 750i
1996 Mercedes E300D
1994 BMW 740i
2006 BMW 330xi (manual)
1999 E300DT Smoke silver/black 253k
2012 BMW 535i Xdrive M-Sport
1984 300TD-T 304k
1988 Mercedes 560SEL (parts car)
2010 BMW 550i xdrive
2017 Audi A4 Presitge
1979 300SD 313k
2003 E500 189k

It is supposed to stay in 2nd while stopped and drop into 1st when you take your foot off the brake. There is a relay that control it but it has been many years since I dealt with one of those.