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The ASE L1 exam has 60 questions and runs 2 hours 30 minutes.
These 10 free ASE L1 questions are organized by exam domain, so you can see how each part of the ASE Advanced Engine Performance Specialist (L1) blueprint is tested. Reveal the answer and explanation under each question.
Compression readings are 181, 180, 154, 179, 182, and 180 psi. Service information requires every cylinder to be within 10% of the highest reading. Adding oil does not raise the 154-psi cylinder, and leak-down air is heard at the tailpipe. Which conclusion is supported?
Correct answer: A - The low cylinder has an exhaust valve or valve-seat leak
At 3,500 rpm under load, desired and actual intake-cam advance agree on both banks. VVL is commanded to high lift on both banks. Service information identifies 0.5 V as low-lift feedback and 4.5 V as high-lift feedback. Bank 1 reads 4.5 V, Bank 2 remains at 0.5 V, and only Bank 2 shows reduced airflow and power. Which part of the system remains suspect?
Correct answer: A - The Bank 2 VVL actuator, circuit, or lift mechanism
An emissions repair is complete. The MIL is off, no pending or confirmed DTC has returned, the related permanent DTC is still displayed, and that monitor remains NOT COMPLETE. Technician A says disconnecting the battery will erase the permanent DTC. Technician B says the OBD system must run the relevant monitor and verify that the fault is gone. Who is correct?
Correct answer: B - Technician B only
MAP, fuel-pressure, and A/C-pressure PIDs all read at their minimum values. The shared 5-volt reference measures 0.2 V with the sensors connected and 5.0 V at the ECM when the harness is disconnected. Unplugging the A/C-pressure sensor restores 5.0 V and returns the other two PIDs to normal; substituting a known-good A/C-pressure sensor keeps the reference at 5.0 V. Which single fault accounts for all of the readings?
Correct answer: C - The original A/C-pressure sensor is internally shorted
An engine cranks normally, starts, and stalls almost exactly two seconds later on every attempt. Engine speed and fuel pressure remain valid, the starter is never inhibited, the Valid Key PID is NO, and injector command is removed immediately before the stall. Diagnosis should focus on:
Correct answer: D - The immobilizer key-validation and network-message path
Cylinder 4 misfires only during a wide-open-throttle hill climb. Its secondary firing line reaches 28 kV and burn time is 0.6 ms; the stated normal values are 10-16 kV and 1.2-1.8 ms. Primary current, injector balance, compression, bank fuel trim, and an intake smoke test are normal. The waveform points to:
Correct answer: B - Excessive spark-plug gap or high secondary resistance
A fully warmed engine is in closed loop. At idle, Bank 1 STFT is +13% and LTFT is +10%; Bank 2 STFT is +12% and LTFT is +11%. At 2,500 rpm, total trim on each bank falls to +4%. Fuel pressure and volume remain in specification under load, MAF response is plausible, and both upstream sensors respond correctly to induced rich and lean conditions. Which fault pattern fits these results best?
Correct answer: D - An intake, PCV, or brake-booster leak downstream of the MAF
A gasoline direct-injection engine loses power under load. Low-side pressure is 55 psi with a 50-60 psi specification. Commanded rail pressure is 1,500 psi, but actual rail pressure remains near 100 psi. An approved pressure transducer was installed using the required depressurization procedure; its running reading agrees with the scan value. Low-side pump volume and injector leak-down are normal. Where should diagnosis continue?
Correct answer: B - The high-pressure pump, control valve, or cam drive
An engine-off natural-vacuum test is run with all stated enable criteria satisfied. After the vent is open for 10 minutes and then closed for 4 minutes, tank pressure changes only 0.6 in. H2O; the pass requirement is greater than 1.0 in. H2O. The specified strategy says an initial failure is followed by a 2-minute vent-open period and then a 20-minute sealed observation. The prescribed next step is to:
Correct answer: C - Open the vent for 2 minutes, reseal the system, and observe for 20 minutes
During a stabilized no-load emissions test, HC is 1,200 ppm, CO is 0.05%, O2 is 8%, CO2 is 7%, and NOx is 50 ppm. The cylinder 5 misfire counter is rising, injector pulse is present, and the spark plug is fuel-wet. These readings are characteristic of:
Correct answer: C - A fueled misfire on cylinder 5
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