Tach tantrum part 2

[jrjajs]

I need some advice from somebody here. The tach which was pegging itself returned to normal operation for a short time. Now it seems that if I let the vehicle sit for a long period of time say 18-24 hours when I start it up the tach is fine. Then by the time the warm up is over it is pegged again. this is really strange.
Any help would be greatly appreciated.

[bojangles]

really sounds like a loose wire, ground lug or something, i have no idea really but i doubt it is the tach itself...

[jrjajs]

I have thought about that possibility but it seems to be something thing to do with the car as it warms up or maybe when the start up loop changes (can't remember if it is from open to closed or the other way at the moment). so I don't thinnk it is a lose wire, could still be a ground I suppose.