190E 2.3 8V Cruise control fluctuation?

My 85 190E cruise control works but it does not keep a smooth cruising speed. It feels like it is accelerating and decelerating but is keeping the speed constant. When not using cruise speed is smooth and constant. Is there any adjustment or possible suggestions to fix problem?

There aren't any adjustments for the cruise control. The most likely cause for the surge is the cruise computer.

I have the same problem in a 88 300E. I assumed this would be a vacum problem. I'm new to Mercedes so I didn't know about a cruise computer. Thanks for saving me some troubleshooting time.

How difficult is changing the cruise computer and are the readily available.

Thanks much,
Kevin

The cruise control computer receives & sends signals to open the throttle. There isn't any vacuum control on the system. The computer is located in various places depending on model& year.

They are readily available, but the only one that is easy to get to is the 190. It is under the passenger's feet. The 124 and 126 are hard to get to, they are above the driver's feet under the dash panel. Oh yea, rebuilt units are available as well.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

The cruise control computer is easily repairable with minimal knowledge and skill. My 190 was doing the same thing. I removed the computer and took it apart. The entire PCB was full of bad solder connections. So after an hour of resoldering all the connections, it works great now! By the way, the dealer wanted $1100 for a new computer. This is a very common problem with these.... Good Luck