ASE A8 Engine Performance Test
Time Remaining: 50:00
1. An EFI engine is running rough and stalling at idle. The MAP sensor's vacuum hose is loose and cracking. Technician A says this sensor measures air mass to establish the base pulse of the engine's fuel injectors. Technician B says this sensor measures changes in intake manifold pressure. Replacing this hose will restore its path to manifold pressure. Who is correct?
2. A vehicle has a momentary hesitation only during acceleration. The MOST likely cause of this condition is:
3. A four cylinder EFI engine has an engine code indicating insufficient EGR flow. The EGR solenoid has been tested and found to be faulty. This faulty solenoid will result in which of these conditions?
4. A vehicle with an enhanced EVAP system is scanned and a code indicating a small evaporative emissions leak is detected. A loose or cracked gas cap is suspected. Technician A says the cap contains a vacuum and pressure relief valve, a small crack in the cap will not illuminate the check engine light. Technician B says the tank contains a sensor. The PCM will sense low tank pressure, set a code and illuminate the check engine light. Who is correct?
5. Technician A says an AF (Air/Fuel) sensor is designed to reach and keep an engine at stoichiometry. Technician B says stoichiometry is 15.7:1 air to fuel mixture. Who is correct?
6. Two technicians are discussing turbochargers. Technician A says the boost pressure sensor provides the intake manifold's boost pressure to the PCM. Technician B says a leaking wastegate diaphragm affects exhaust flow through the turbine wheel. Who is correct?
7. The engine control module uses all of these inputs to calculate air-fuel ratio and speed control EXCEPT:
8. An engine with a viscous fan clutch is running hot only at stop lights. Technician A says this type of fan should be checked for leakage. Technician B says a defective relay may cause this fan to become inoperative. Who is correct?
9. A fuel pressure test at the fuel rail of a sequential fuel injected engine indicates low fuel pressure. All of these would cause this test result EXCEPT:
10. An oxygen sensor is sending a consistent signal of .20 volts. Technician A says this indicates a rich fuel mixture. Technician B says the PCM will adjust fuel trim to compensate for a disconnected vacuum hose. Who is correct?
12. Technician A says the heater circuit in an oxygen sensor brings the sensor to operating temperature. Technician B says the engine control module uses the oxygen sensor's voltage signal to adjust the air-fuel ratio in closed loop. Who is correct?
13. Two technicians are discussing a turbocharged engine. Technician A says the wastegate is a component used to control boost pressure. Technician B says when opened, the wastegate diverts exhaust gas from the turbine wheel. Who is correct?
14. An emissions test is performed on a six cylinder engine. The test indicates high levels of NOx. The MOST likely cause of this condition is:
15. Two technicians are discussing a voltage drop test. Technician A says to perform a voltage drop test if a corroded ground connection is suspected. Technician B says to perform a voltage drop test if excessive resistance is suspected. Who is correct?
16. Technician A says a stuck open PCV valve will cause a rich fuel condition. Technician B says the PCV system removes blowby gases from the crankcase. Who is correct?
17. A crankshaft position sensor's companion sprocket has a broken tooth. Technician A says the camshaft position sensor monitors crankshaft speed and rotation. Technician B says the vehicle's engine will operate and perform normally. Who is correct?
18. A vehicle has a check engine light with codes indicating a problem with the enhanced evaporative emission system and a rich fuel condition. Technician A says a defective evaporative purge valve will cause a rich air-fuel ratio. Technician B says the tank pressure sensor will notify the PCM of excessive tank pressure. Who is correct?
19. A cylinder power balance test is being performed on a four cylinder engine. A spark plug wire is removed from its corresponding spark plug and a slight drop in rpm is noticed. Which of the following is correct?
20. A cylinder compression test is performed on an eight cylinder engine. The test results above indicate:
21. Technician A says the PCM will advance ignition timing when it receives a voltage signal from the knock sensor. Technician B says this sensor sends an AC signal to the PCM when it detects ping or spark knock. Who is correct?
22. A misfire is detected at the #3 cylinder of a COP ignition system. There is no power at the Bat+ terminal of the coil. Which of the following is the MOST likely cause of this condition?
23. An enhanced EVAP system has a code indicating a gross leak detected. Which of the following is the MOST likely the cause of this condition?
24. A catalytic converter is damaged from heat. Technician A says this heat damage is caused by cylinder misfiring. Technician B says this heat damage is caused by low fuel pressure. Who is correct?
25. A vehicle has a fuel trim of -5 at idle and -25 at cruise. The vehicle has a steady oxygen sensor reading of 800Mv. When a vacuum hose is disconnected from the intake manifold there is no change in the oxygen sensor's output. This condition is caused by:
26. A vehicle cranks but will not start. As the technician turns the ignition key the security light continues to flash slowly. Which of these is MOST likely the cause of this condition?
27. A vehicle is backfiring and has a lack of power. Technician A says it may be 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?
28. Two technicians are discussing 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?
29. Technician A says when the vacuum hose is disconnected from a vacuum operated fuel pressure regulator, the fuel pressure should increase. Technician B says a restricted fuel return line will cause low fuel pressure and a lean fuel condition. Who is correct?
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?
31. An EGR valve vacuum solenoid has 18 "hg. as its vacuum source. The resistance checks out OK. Vacuum pressure is manually applied to the EGR valve with a pump and a slight stumble is noticed. There is little drop in rpm. This is caused by:
32. A cylinder power balance test is being performed on a vehicle with sequential fuel injection. Two adjacent cylinders are under performing. Technician A says this could be caused by a restriction in the fuel injectors. Technician B says this could be caused by leaking secondary insulation. Who is correct?
33. A COP ignition system has no spark at any of the coils. Which of these is MOST likely the cause?
34. Technician A says the MAF sensor is located on the intake manifold, and informs the PCM of intake manifold pressure. Technician B says the MAF sensor senses air volume in the air tube. It's signal indicates engine load to the PCM. Who is correct?
35. Technician A says a throttle position sensor is a potentiometer that indicates throttle angle. Technician B says a throttle position sensor can be tested for resistance with an ohmmeter. Who is correct?
36. After performing a wet compression test, the pressure in each of the cylinders increased. Technician A says this is caused by incorrect camshaft timing. Technician B says this is caused by worn piston rings. Who is correct?
37. A vacuum gauge is connected to a port on the intake manifold of an engine with poor performance. The needle on the gauge fluctuates between 15 "hg and 20 "hg vacuum at idle. This vacuum gauge reading indicates:
38. Technician A says a stuck closed (EGR) exhaust gas recirculating valve will cause an engine to stumble or stall. Technician B says a stuck open EGR valve will cause detonation. Who is correct?
39. A vehicle is emitting black smoke from its tailpipe at idle. Which of the following is causing this condition?
40. An engine suffers from a lack of power during acceleration. A vacuum test is being performed. At 2500 rpm the vacuum gauge needle drops slowly and then reads 10 "hg. Which of the following is causing these vacuum test results?
Please select an answer