Question 1

Where is the fuel injected in an engine equipped with gasoline direct injection?

Accepted Answer

In an engine equipped with gasoline direct injection, the fuel is injected directly into the combustion chamber. This allows for more precise fuel delivery and better control over the combustion process, resulting in improved fuel efficiency and performance.

Question 2

The fuel pump inside the fuel tank on a vehicle equipped with gasoline direct injection produces about what pressure?

Accepted Answer

Vehicles equipped with gasoline direct injection typically require higher fuel pressure to efficiently and effectively inject the fuel directly into the combustion chamber. The fuel pump inside the fuel tank on these vehicles typically produces a pressure of about 50 to 60 PSI.

Question 3

The high-pressure fuel pumps used in gasoline direct injection (GDI) systems are powered by ________.

Accepted Answer

The high-pressure fuel pumps in gasoline direct injection (GDI) systems are typically driven by the camshaft, which allows them to synchronize with the engine's operation and provide fuel at the necessary pressure when the engine's valves are open.

Question 4

The high-pressure fuel pressure is regulated by using ________.

Accepted Answer

An electric pressure control valve is commonly used in modern fuel systems to regulate high-pressure fuel, allowing for precise control based on engine demands.

Question 5

GDI fuel injectors operate under a pressure of about ________.

Accepted Answer

GDI fuel injectors operate under a pressure of about 500 to 2,900 PSI.

Question 6

The fuel injectors used on a gasoline direct injection system are pulsed ON using what voltage?

Accepted Answer

The answer of The fuel injectors used on a gasoline...

Question 7

Which mode of operation results in a richer air-fuel mixture near the spark plug?

Accepted Answer

In stratified mode of operation, the air-fuel mixture is not evenly distributed throughout the combustion chamber. Instead, a rich air-fuel mixture is near the spark plug and the rest of the chamber is lean. This results in better combustion and higher efficiency.

Question 8

All of the following are advantages of gasoline direct injection EXCEPT ________.

Accepted Answer

Gasoline direct injection actually improves throttle response. Therefore, decreased throttle response is not an advantage of this technology.

Question 9

All of the following are disadvantages of gasoline direct injection EXCEPT ________.

Accepted Answer

The disadvantages listed are A, C, and D. Choice B is not a disadvantage but rather a benefit of gasoline direct injection, as it requires less fuel for acceleration due to the more precise fuel delivery system.

Question 10

A lack of power from an engine equipped with gasoline direct injection could be due to ________.

Accepted Answer

Carbon buildup on both the intake valves and the injectors can cause a lack of power in an engine with gasoline direct injection. Noisy injectors may be a symptom of this issue, but they are not the root cause.

Question 11

Some engines that use a GDI system have carbon issues ________.

Accepted Answer

Carbon issues in GDI systems occur on both the fuel injectors and exhaust valves.

Question 12

Why should any high-pressure line removed be replaced with a new part on a GDI system?

Accepted Answer

The ball-ends of high-pressure lines in a Gasoline Direct Injection (GDI) system deform when tightened, creating a seal that is specific to the connection made. If these lines are removed and then reused, they may not seal properly due to the deformation of the ball-ends, leading to potential leaks or other issues in the high-pressure fuel system.

Question 13

GDI equipped engines have a higher efficiency due to a ________ compression ratio.

Accepted Answer

GDI engines can have higher compression ratios because the fuel is injected directly into the combustion chamber, which allows for better control over the fuel/air mixture. This can result in better fuel efficiency and power output.

Question 14

Gasoline direct injection (GDI) is also known as ________.

Accepted Answer

The answer of Gasoline direct injection (GDI) is also known...

Question 15

An engine equipped with GDI may have up to a ________ percent improvement in fuel economy.

Accepted Answer

GDI (Gasoline Direct Injection) engines can have up to a 25 percent improvement in fuel economy compared to traditional fuel injection systems due to more precise fuel delivery and better air-fuel mixture.

Question 16

The SIDI high pressure fuel pump uses a single-barrel piston plunger that is driven by a(n) ________.

Accepted Answer

The SIDI high pressure fuel pump uses a single-barrel piston plunger that is driven by a three-lobed cam.

Question 17

When the fuel pressure regulator is deactivated, the fuel pressure defaults to ________.

Accepted Answer

When the fuel pressure regulator is deactivated, the fuel pressure defaults to low pressure mode, which is typically around 5-10 PSI. This is because the regulator is responsible for maintaining a steady and constant fuel pressure by adjusting the amount of fuel flow to the injectors. Without the regulator, the fuel pump will continue to pump fuel at its maximum pressure, but the engine's fuel system will not be able to handle this high pressure without causing damage or leaks. Therefore, low pressure mode is the default and safe setting when the regulator is not active.

Question 18

A GDI system operating in stratified mode results in ________.

Accepted Answer

In stratified mode, the air-fuel mixture is intentionally made lean in most of the combustion chamber, but rich near the spark plug tip for easier ignition. Therefore, option C is correct as it describes the result of a GDI operating in stratified mode. Option A is incorrect as the air-fuel mixture is not evenly distributed in stratified mode. Option B is also incorrect as black smoke is usually a sign of incomplete combustion, which is not the goal of stratified mode. Option D is incorrect as there is a correct choice.

Question 19

What GDI operating mode is used to burn sulfur from the NO_xcatalyst?

Accepted Answer

Stratified heating mode is used in gasoline direct injection (GDI) systems to increase the exhaust temperature, which helps in burning off sulfur deposits from the NOx catalyst.

Question 20

When compared to a port fuel injected engine, a GDI engine will have a(n) ________ compression ratio.

Accepted Answer

A GDI (Gasoline Direct Injection) engine has a higher compression ratio compared to a port fuel injected engine. This is because GDI engines can inject fuel directly into the combustion chamber at a higher pressure, allowing for a more efficient combustion process and therefore a higher compression ratio.

Quiz 23: Gasoline Direct-Injection Systems