With the cylinder head and intake manifold sealing surfaces thoroughly cleaned, we added four, 3-inch lengths of the wax string to each corner of the engine and bolted the intake back on.

is open, which is determined by how far down the accelerator pedal has been pushed. The throttle position controls the amount of air that flows into an engine’s intake manifold; when it’s ...

When the throttle is wide open and air is rushing into the intake manifold (causing a drop in pressure), the MAP sensor signals the engine computer to send more fuel. When the throttle closes ...