ASE L1 Domain 1: General Powertrain Diagnosis Welcome to your ASE L1 Domain 1: General Powertrain Diagnosis 1. ASE L1: General Powertrain Diagnosis A technician is diagnosing an engine that cranks normally but does not start. The spark, fuel pressure, and compression have been verified as within specifications. Which of the following should be checked NEXT? A. Engine coolant temperature sensor B. Ignition switch signal C. Timing belt alignment D. Battery voltage during cranking None 2. ASE L1: General Powertrain Diagnosis A vehicle with a port fuel injection system has a rough idle and a long crank time before starting. A scan tool indicates a rich condition at idle but not during higher RPMs. What is the MOST likely cause? A. Faulty fuel pump B. Leaking fuel pressure regulator diaphragm C. Clogged fuel return line D. Weak ignition coil None 3. ASE L1: General Powertrain Diagnosis A vehicle with a coil-on-plug ignition system has an intermittent misfire. The misfire does not move with the ignition coil or spark plug when they are switched to another cylinder. What is the NEXT best step? A. Swap fuel injectors between cylinders. B. Perform a leak-down test on the affected cylinder. C. Check the compression of the affected cylinder. D. Examine the wiring harness to the ignition coil for the affected cylinder. None 4. ASE L1: General Powertrain Diagnosis A turbocharged engine is experiencing low power under acceleration. The turbocharger and intercooler system are free of leaks. The engine does not have any misfires, and fuel delivery is correct. Which of the following could be the cause? A. A faulty mass air flow sensor B. Inoperative EGR system C. A slipping transmission torque converter D. Incorrect wheel alignment None 5. ASE L1: General Powertrain Diagnosis A direct injection engine is exhibiting a low-speed pre-ignition (LSPI) condition. Technician A says that using an oil with a higher octane rating may resolve this condition. Technician B says that LSPI can be caused by excessive carbon buildup on the piston tops. Who is correct? A. Technician A only B. Technician B only C. Both Technician A and B D. Neither Technician A nor B None 6. ASE L1: General Powertrain Diagnosis When diagnosing an electronically controlled automatic transmission, you notice that the transmission only engages harshly in reverse, but operates normally in forward gears. The MOST likely cause of this condition is: A. A faulty transmission range sensor. B. Worn reverse gear clutches. C. A malfunctioning line pressure solenoid. D. Defective transmission fluid temperature sensor. None 7. ASE L1: General Powertrain Diagnosis The scan tool displays a P0335 code - Crankshaft Position Sensor "A" Circuit Malfunction. The vehicle experiences intermittent stalling. The crankshaft position sensor has been replaced without resolution. What should be checked NEXT? A. Timing belt for proper tension B. Crankshaft reluctor wheel for damage C. Camshaft position sensor operation D. ECM power and ground circuits None 8. ASE L1: General Powertrain Diagnosis A vehicle with gasoline direct injection (GDI) has a pattern failure of carbon build-up on intake valves. Which of the following is MOST likely to prevent recurrence after cleaning? A. Installing a colder spark plug B. Using fuel with more detergents C. Applying a protective coating to the valves D. Frequent oil changes using synthetic oil None 9. ASE L1: General Powertrain Diagnosis A vehicle has a history of setting a P0420 - Catalyst System Efficiency Below Threshold (Bank 1) code intermittently. The catalytic converter has been replaced and the fuel trim values are normal. The MOST likely cause for the recurring code is: A. A weak fuel pump B. An intermittent exhaust leak upstream of the O2 sensor C. A malfunctioning downstream O2 sensor D. A misfiring spark plug None 10. ASE L1: General Powertrain Diagnosis A technician has determined that a vehicle's mass air flow sensor is reading 10% lower than expected at idle. Which of the following is LEAST likely to be a consequence of this condition? A. Increased HC emissions at idle B. Premature catalytic converter failure C. Excessive fuel consumption at highway speeds D. Positive fuel trim corrections at idle None 1 out of 10 Time is Up! Time's up
