ASE A8 Engine Performance Practice Test

26. A vehicle cranks but will not start. As the technician turns the ignition key, the security light flashes slowly. Which of these is the MOST likely cause of this condition?

  • A. The transponder.
  • B. A faulty PCM.
  • C. No power to the fuel injectors.
  • D. A dead battery.

26.

Answer A is correct. The vehicle's security system electronically prevents the engine from starting. Most use an ignition system with an antenna ring and a unique transponder or chip key. If the key or transponder signal does not match the program in the control module, the engine will not start.

Answer B is wrong. Notice if the security light is flashing while attempting to start the vehicle. Unlock and relock the doors with the key fob and try again. Also, the tension in the ignition switch may have worn in time. Try the spare key to rule out a faulty key as the cause.

Answer C is wrong. The security system may be preventing startup. For example, the security system will disable the starter or the fuel injectors to avoid theft.

Answer D is wrong. The engine would not turn over if it had a dead battery.

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27. After replacing a leaking fuel injector on an engine with fault code P0172, indicating a rich air-fuel ratio, the engine is still backfiring and lacks power. Technician A says the rich air-fuel mixture could have clogged the catalytic converter. Technician B says to use a vacuum gauge to diagnose a restriction in the exhaust system. Who is correct?

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

27.

Answer A is wrong. A clogged catalytic converter will result in a lack of engine power. Use a back pressure tester to test for restricted exhaust flow.

Answer B is wrong. A vacuum gauge can be used. If the needle drops steadily during acceleration, there's a restriction in the exhaust or intake.

Answer C is correct. Both technicians are correct.

Answer D is wrong. Both technicians are correct.

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28. Two technicians are discussing OBD II code P0301. Technician A says the P in the code stands for the powertrain. Technician B says the 0 in the code means it is manufacturer-specific. Who is correct?

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

28.

Answer A is correct. (P0301) The P in an OBD II code stands for powertrain.

Answer B is wrong. (P0301) The 0 stands for SAE or a generic code, and a 1 stands for a manufacturer-specific code.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

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Diagram of automotive PCM engine control system.

29. Component A in the schematic diagram above is:

  • A. A splice in the ground circuit for MAP sensor.
  • B. A splice in the signal circuit for MAP sensor.
  • C. A connection in the signal circuit for MAP sensor.
  • D. A connection in the reference circuit for MAP sensor.

29.

Answer A is wrong. This is the schematic symbol for a connector. It's part of the signal circuit for the manifold absolute pressure sensor.

Answer B is wrong. A splice is denoted as a solid black dot that connects two wires.

Answer C is correct. This is the connector for the signal circuit of a MAP sensor.

Answer D is wrong. The reference voltage circuit is labeled 5V ref.

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30. A vehicle has white exhaust smoke emitting from its tailpipe. Which of the following could be the cause?

  • A. A leaking fuel injector.
  • B. A leaking head gasket.
  • C. Leaking valve seals.
  • D. A vacuum leak.

30.

Answer A is wrong. Excessive fuel in the combustion chamber produces a rich air-fuel mixture and black-colored exhaust.

Answer B is correct. A leaking head gasket results in white-colored exhaust. White exhaust smoke is an indication that coolant is entering the combustion chamber.

Answer C is wrong. When valve seals leak, oil enters the combustion chamber, causing the vehicle to emit blue-gray exhaust from its tailpipe.

Answer D is wrong. A vacuum leak may result in a lean air-fuel ratio or a hissing sound, but not white-colored exhaust.

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