Recently installed white gauges on a 86 300E. Noticed yesterday and today, the tach seems to work only after the car has been driven for awhile. When first starting the car after sitting overnight, the tach isn't working. Then sometimes it starts to work after haven driven for half an hour or more. Did a search on this, and came up with something related to a piece on the driver's side fenderwall, sticking a cigarette butt into it?? (mostly on diesels though), does this piece and technique also apply to the 300E series?