ASE A8 Engine Performance Practice Test

26. A vehicle cranks but will not start. As the technician turns the ignition key the security light continues to flash slowly. Which of the following is MOST likely the causing this no start condition?

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

26.

Answer A is correct. Transponder or chip keys are used for security in many late model vehicles. When the wrong key or if the signal does not match the program in the control module, the vehicle will not start. The security system may be at fault. 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 resistance in the key may have changed in time; try the spare key to rule out a faulty key as the cause.

Answer B is wrong. The problem is most likely caused by a faulty ignition switch, key or pass lock sensor.

Answer C is wrong. This would result from no power coming from the PCM. The light would not be flashing if the PCM has an open between it and the fuse. The security system would be the cause, no power at the injectors would be the result.

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

27. A fault code indicating a rich air fuel ratio has been repaired by replacing a leaking fuel injector. The vehicle is now backfiring and has a lack of power. Technician A says the rich fuel mixture has clogged the catalytic converter and a back pressure test should be performed. Technician B says a vacuum gauge can be used 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 steady 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.

28. Two technicians are discussing OBD code P0301. Technician A says the P in the code stands for 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 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.

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.

30. An EFI engine stalls and then starts back up. Sometimes it takes several tries to start. Technician A says a loose connection at the crankshaft position sensor would result in this condition. Technician B says an open at the crankshaft position sensor would result in this condition. Who is correct?

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

30.

Answer A is correct. A loose connection in an electrical circuit will result in intermittent operation.

Answer B is wrong. The engine would not start if there's an open in the crankshaft position sensor's circuit.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.