ASE L1 case studies
ASE L1 · Put your knowledge to work in context.
ASE L1, the Advanced Engine Performance Specialist certification, is one of the certification tests offered by the National Institute for Automotive Service Excellence (ASE), an organization that certifies automotive service professionals across the country. The L1 is aimed at experienced driveability and diagnostics technicians - the people who chase intermittent misfires, fuel-trim drift, scan-tool data that does not add up, and vehicles that come back after parts have already been thrown at them. The ASE L1 case studies are 5 cases and about 3,153 words.
1The Wet Test Says Rings, the Leakdown Says Valve
A 2008 2.4 L four-cylinder with 142,000 miles comes in with a flashing MIL and P0302. The misfire counter shows cylinder 2 misfiring heavily at idle and light cruise, but the count stops above about 2,500 rpm.
622 words, about 3 min2Both Banks Lean, but Only at Idle
A 2006 V6 with 98,000 miles sets P0171 and P0174. Freeze frame at idle: 620 rpm, MAF 3.1 g/s, long-term fuel trim +24 percent on bank 1 and +22 percent on bank 2, short-term trim +8 and +7, ECT 190 F, IAT 90 F.
612 words, about 3 min3Misfire Only on the Long Hill
A 2010 V8 with 118,000 miles sets P0300 only during a long uphill pull at wide-open throttle. At idle and steady cruise the misfire counters stay at zero.
603 words, about 3 min4One Bank Rich, and the Oxygen Sensor Is Not Blinking
A 2004 V6 with 130,000 miles sets P0172. Long-term trim is -16 percent on bank 1 and -2 percent on bank 2; short-term is -5 on bank 1.
632 words, about 3 min5Fails the Loaded Emissions Test on NOx Only
A 2002 2.0 L four-cylinder with 165,000 miles fails a loaded steady-state emissions test. At 15 mph: NOx 420 ppm against a 600 limit, HC 40 ppm against 120, CO 0.12 percent against 0.70.
684 words, about 3 min