Hoping to see if this is a common issue for 1st Gen drivers:

On my 84SE, 167k mi, stock RE-EGI - on cold mornings, the tachometer doesn't register engine RPM until the engine is warmed up sufficiently, i.e., either that, or the passenger compartment warms up.

The tach will then suddenly 'jump' up to the current engine RPM, and then register correctly.

Is this a grease that's congealed back there, or some other easily remedied problem that I can fix. Works great during spring/summer/fall, just winter temps cause the tach not to register correctly until warm.

Also, not a problem with trailing coil wiring or other ignition problems, as the car is running very well right now. TIA,

 

you might try cleaning the tach connections, its most likely a bad tach though

mike

 

I've never had a problem with the tach on my 82 GS in the cold weather. Not that that really helps you, but in case you're wondering how common that is...

 

Mine does the exct same thing......I always wondered how to fix it.....I think Ill just get an autometer tach

 

in some cases there's actually a crack in the circuit board. In the cold, the crack is large as the board has shrunk. As the engine (and, subsequently, the interior) heats up the circuit board expands, closing the circuit.

This is more common to Detroit cars than Hiroshima fine automobiles, but if you've the patience to pull your instrument cluster without cracking it further it's something worth checking