Economy meter doesn't work regularly. on 1992 Mercedes-Benz 300SL

The economy meter very often fails to work. Sometimes it works and sometimes it doesn't at all. Timing and tuning done. When the meter works, the car functions very smooth and with good pick up power. Otherwise it drags a bit when it fails to work. All checks have been done.

Asked by for the 1992 Mercedes-Benz 300SL
Give Peter a call at Silverstar motors in vienna. He is a Mercedes expert.