Ford Windstar Owner's Manual page 25

Instrumentation
Tachometer (If equipped)
The tachometer will show you the engine's speed measured in
revolutions per minute (RPM).
The tachometer may move slightly when the key is placed in
the ACC or ON position, with the engine off. This is normal
and does not affect the performance of the tachometer when the
engine is running.
Some vehicles are equipped with an engine speed (RPM)
limiting device that is contained within the Electronic Engine
Control Module. The purpose of this device is to maintain peak
engine speed (RPM) below a specified limit. (Engine speed
limits may vary based on engine size.)
If you are experiencing an "engine cut-out" condition at high
speeds, it may be the result of this limiting device. It is a
normal condition and can be avoided by reducing
vehicle/engine speed.
The tachometer
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