I found 2 relays inside the additional relay box (just front of fuse box) in 1991 Mercedes 2.3.

What is those relays for? One is connected to port C connector, another one is connected to port E connector.

Thanks

OK! I found out the port E is for intake manifold pre-heater.

What is that part in the intake manifold on 2.3L engine? Hope anyone can help me out. Thanks

R8/2 is the Intake Manifold Preheater, there is a wire connected to the bottom of it.
K3/1 is the Intake Manifold Preheater relay module.

I had this part off my 2.3 when I replaced the head gasket.

Look on page 33 of the link below.
http://web.archive.org/web/20060526115323/mb.braingears.com/201_DISK1/PDF/30009.pdf

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Thanks your help slk230red!!!!