ASE A8 Engine Performance Practice Test

41.Technician A says a turbocharger boost pressure sensor provides the intake manifold's boost pressure to the ECM. Technician B says a faulty boost pressure sensor will affect vehicle acceleration. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

41.

Answer A is wrong. The boost pressure sensor provides the intake manifold's boost pressure to the ECM.

Answer B is wrong. The engine management system uses this signal to adjust the air-fuel mixture; a faulty BPS results in poor acceleration and low fuel mileage.

Answer C is correct. Both technicians are correct.

Answer D is wrong. Both technicians are correct.

Diagram of automotive PCM engine control system.

42. The vehicle in the diagram above contains:

  • A. A (COP) coil on plug ignition system.
  • B. A wastespark ignition system.
  • C. A sequential port electronic fuel injection system.
  • D. A (TBI) throttle body fuel injection system.

42.

Answer A is wrong. Answer B is correct.

Answer B is correct. This is a diagram of a wastespark ignition system.

Answer C is wrong. This is a multiport fuel injection system. The PCM actuates two injectors at once

Answer D is wrong. Answer B is correct.

43. An engine with a viscous fan clutch overheats while the engine idles. Technician A says fluid could be leaking from the clutch assembly. Technician B says the system's relay may be sticking open. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

43.

Answer A is correct. This type of fan operates with a silicon-type fluid. Fluid leaking from the assembly limits the operation of the viscous fan clutch.

Answer B is wrong. The ECM uses a relay to control the motor in an electric radiator fan circuit.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

44. A fuel pressure test performed at the fuel rail of an SFI sequential fuel injection engine indicates lower than specified fuel pressure. All of the following cause low fuel pressure EXCEPT:

  • A. A poor ground in the pump circuit.
  • B. A kink in the fuel return line.
  • C. A restricted fuel filter.
  • D. A faulty fuel pump.

44.

Answer A is wrong. A poor ground or power condition would result in low fuel pressure.

Answer B is correct. This is an EXCEPT-type question. A restricted fuel return line would increase fuel pressure at the rail.

Answer C is wrong. A restricted or clogged fuel filter would result in low fuel pressure at the rail.

Answer D is wrong. A defective fuel pump would result in low fuel pressure at the rail. It is the most common cause of low fuel pressure.

Automotive engine sensor.

45. The sensor illustrated above is a:

  • A. Thermistor
  • B. Permanent Magnet
  • C. Potentiometer
  • D. Pressure Switch
Automotive engine sensor.

45.

Answer A is wrong. Thermistors measure temperature.

Answer B is correct. The sensor above is a permanent magnet sensor. Crankshaft and camshaft position sensors are used by engine manufacturers as position sensors.

Answer C is wrong. The Throttle Position (TP) sensor is located on the throttle body of a fuel-injected engine.

Answer D is wrong. An oil pressure switch sends a signal directly to the driver’s instrument panel or the engine control module.