mine does it too, did it for 2 years now on idel

i don't know what car / engine this is from but check the crank sensor!

Sounds to me like you cana loose connection on the rev counter wiring, the motion of turning sharp corners must be making it worse also.

if the alt is bust itll stuff the batterey and evtually your car wont work

is that particulalry important or just an inconvenience?

ive had a car where the revsfly up and down (just the needle) was an overcharging alternator

no the revs are normal, its the counter that dies

is it the counter thats up or down or the actual revs??

Sometimes when im driving, my rev counter goes mental, will spike frequently, like once every maybe 20 or 30 seconds, and if i turn left really sharp it goes right to 0 like its disconnected then when the wheel is back at centre the rev counter springs into life again. This only happens every now and then though, it happened all day yesterday and then stopped today. its well wierd. I checked all the connections and they are all fine