what is wrong?? bad tach or slipping clutch?

Eric Mckenna · 05-31-2005, 08:01 AM

on start up every morning the tach will swing into the 4-5 range before the car starts up.. but once it's started it will not do it again if I turn it off .. it will fire right up with out the tach swinging like that.. is it the cold clutch and a bit of slippage on start up? or what.. should I adjust the clucth and see what happens?

Eric

wholberg · wholberg's Garage

If it does not do it while the car is running, then I would just leave it alone. I don't see how the clutch can be involved because it's either disengaged (in gear, pedal in) or the car is in neutral. The tach is electric, so while it's cranking the tach is not "counting" the ignition pulses accurately.

My 87 Carrera has never done this, but I think my 78 911SC used to do what you describe. As soon as the engine fired, it dropped down to the correct RPM.

Eric Mckenna · 05-31-2005, 08:46 AM

yeah that's JUST what it is doing.. but it JUST started last week.. so I guess I'll leave her alone.
Thanks man.

Ron.G · 05-31-2005, 08:54 AM

The tach has a tendency to jump around/ act strangely when voltage is low. I'd clean your battery terminals and or check your battery.
You might have low battery voltage and when you turn the key the tach goes wacky but when you start the car every thing is fine.

Just a guess,but It would'nt hurt to check the battery or your grounds.