Question

An engine equipped with electronic fuel injection has a loose exhaust manifold.

A says that a loose manifold may cause noisy engine operation.
B says that the loose manifold may cause poor vehicle driveability

-A
-B
-Both
-Neither

Answer 1

Both statements regarding a loose exhaust manifold are correct. It can cause noisy engine operations and poor vehicle driveability by affecting exhaust flow and disrupting sensor readings, which compromises fuel injection timing.

Step-by-step explanation:

The question pertains to the effects of a loose exhaust manifold on an engine equipped with electronic fuel injection. The correct option in this scenario is 'Both' because:

• A loose exhaust manifold can indeed cause noisy engine operation. This happens because the exhaust gases may escape from gaps between the manifold and the engine, creating an audible sound that can be described as a loud rumbling or a popping noise. This sound usually gets louder as the engine RPM increases.
• The loose manifold can also affect vehicle driveability due to the disruption of the engine's backpressure and exhaust flow. This, in turn, can lead to incorrect air-fuel mixture readings by the oxygen sensors, and consequently, improper fuel injection timing, affecting the overall performance of the vehicle.

To rectify a part that resonates at the engine's frequency, engineers can either change the length (L) of the part or alter the material with a different mass (M), so that it does not resonate at the same frequency as the engine. The modifications would aim to eliminate the unwanted oscillations to prevent noise and potential premature part failure.