ATASA 5 th Study Guide Chapter 30 Pages 899­921 Name______Electronic Fuel Injection 68 Points Due Date______

1. EFI systems are ______controlled and designed to provide the correct _____­______ratio for all engine loads, speeds, and temperature conditions.

2. The ideal air/fuel ratio is called the ______ratio and consists of 14.7 parts of air to 1 part of fuel by weight. Note: Different fuels have different stoichiometric ratios.

3. The stoichiometric ratio allows the ______converter to work most efficiently.

4. A ______system determines the amount of air entering the engine with input from the MAP (manifold absolute pressure) (piezo­resistive V­ref) sensor and the RPM sensor.

5. Most engines use a ______system (MAF) to measure the amount of incoming air.

6. During ______, EFI systems rely on input from various sensor before adjusting the air/fuel ratio. (warm coolant, time running, & using active upstream HO2S signals)

7. during ______, EFI systems deliver fuel according to predetermined parameters held in the PCM’s memory. (cold coolant, time running, & ignoring inactive upstream HO2S signals)

8. Fuel ______are solenoids with movable armatures that pulse on when electricity flows through their internal coil of wire. This action delivers a spray of atomized fuel.

9. O­rings on injectors seal them into the intake ______and the fuel ______.

10. Injectors are fed ______voltage and are pulsed on by the PCM controlling the driver circuit ground.

11. The length of time that a PCM grounds the injector to turn it on is called ______.

12. Injector pulse width is expressed in ______of on­time. (Fuel Trim = adjustment)

13. Pulse width can range from 1 to 10 milliseconds. Cold starting requires a ______pulse width.

14. Idle speed is controlled by ______a certain amount of airflow past the throttle plate.

15. ______motors (IAC) are stepper motors used to control idle rpm. 16. Throttle­by­wire systems use a throttle actuator motor (TAC) instead of an IAC. True or False

17. The ______sensor (MAF) calculates the mass of a given amount of air by multiplying its volume by its density. (measured & expressed in grams/second or # per minute)

18. Base pulse width of injectors can also be determined by a ______

______(MAP) sensor which calculates engine load using manifold vacuum.

19. At closed throttle the engine has a ____ MAP value. At WOT a ______MAP value is produce.

20. MAP output is the ______of what is measured on a vacuum gauge.

21. The MAP signal is also used to inform the PCM when the ______valve is open since introducing exhaust into the intake manifold would affect pressure in the manifold.

22. The MAP signal could be used to determine turbo boost. True or False

23. Manifold Absolute Pressure equals the ______pressure minus the intake manifold vacuum. Expressed in inches of mercury (Hg”) BARO – VAC = MAP

24. Signals from the exhaust gas ______(O2S) sensors are the main input to adjust the A/F ratio.

25. Low voltage at the HO2S is a ______exhaust indicator resulting in a rich injector command

26. High voltage at the HO2S is a ______exhaust indicator resulting in a lean injector command.

27. Intake ______temperature sensors (IAT) are necessary since ______air is more dense than warm air, it can burn more fuel than the same volume of warm air.

28. The engine ______temperature sensor (ECT) signals the need for cold A/F enrichment.

29. The ______position sensor (TPS) is a potentiometer.

30. The highly important ______position sensor (CKP) monitors engine speed.

31. The ______position sensor is used to synchronize the timing of injector pulses.

32. ______mode sets injector pulse width using MAF, IAT, ECT, & TPS.

33. ______mode can be either open loop or closed loop based on ECT HO2S, and TPS.

34. A system with 0 milliseconds of pulse width during cranking is in ______mode.

35. There are also ______& ______modes to respond to rapid TPS change.

36. Adjustments made to base pulse width are called fuel ______. A positive fuel trim is an increase in pulse width. A negative fuel trim is a decrease in pulse width.

37. ______term fuel trim (STFT) represents changes made immediately in response to HO2S signals. 38. _____ term fuel trim (LTFT) represents changes made to a new base pulse width by STFT trends.

39. STFT is ______when the ignition is turned off. LTFT remains in the PCM memory.

40. Low pressure _____ systems used 1 or 2 injectors above a throttle plate centrally located atop the intake manifold. Throttle body injection was the transition from carburetors to port injection.

41. ______injection (MPI) locates the injectors close to the valves in the intake manifold, but pulses all injectors at the same time or in banks on engines with V cylinder arrangements.

42. ______(SFI) controls each injector separately, firing just before the intake valve opens.

43. Port injection systems have a ______to control the amount of incoming air.

44. Idle speed is adjustable with a screw on the port injection throttle body. True or False

45. Injectors are fastened to the fuel ______which is a fuel manifold or distribution device.

46. Fuel pulsation ______are used on some rails to reduce fluctuations and to quiet operation.

47. Vacuum­sensitive fuel pressure ______maintain constant pressure drop of the injectors.

48. On Throttle­by­wire systems, a throttle actuator ______responds to input from accelerator pedal position sensors (APP). There are redundant APP and TPS in a throttle­by­wire system.

49. CMFI uses individual ______for each cylinder controlled by a single injector and a fuel pressure regulator mounted right on the CMFI module.

50. CMFI injector pressure is regulated very accurately between ____ to ____ psi. This eliminates vapor lack tendencies, but makes the system sensitive to low fuel pressure problems.

51. ______(GDI) has advantages over SFI, such as precise delivery and the system’s ability to learn the fuel type & adapt to another stoichiometry.

52. GDI injectors deliver fuel ______into the high pressures & high temperatures in the cylinder.

53. Piezoelectric injectors that rely on stacked ______have a faster response time than solenoid­type injectors. They react so fast that they can pulse multiple times in one engine stroke.

54. GDI fuel rail pressures can range from ______to ______psi!

55. GDI can operate in ______burn, ______, or ______mode.

56. For increased mileage, GDI can run as lean as 60:1 using ______charge combustion.

57. GDI engines can operate at higher ______ratios without the need for high octane fuel.

58. To meet OBD­II standards, diesel engines use ______rail injection systems with many of the same inputs as gasoline engine and piezoelectric injectors. Rail pressures are 2,000 to 25,000 psi!