ASE T1 Domain 1: General Engine Diagnosis

During a routine inspection, a technician finds that the engine oil dipstick smells of gasoline. Which of the following could be a potential cause for this issue?

When diagnosing an engine with a suspected timing issue, a technician observes that the camshaft timing marks are aligned, but the crankshaft timing mark is off by several degrees. Which of the following is MOST likely the cause?

A vehicle exhibits a condition where it runs fine at idle but stumbles and misfires under load. There are no DTCs present. What should be checked FIRST?

A technician finds that an engine has low compression in one cylinder. After performing a wet compression test, the compression improves significantly. What is the MOST likely cause?

During an engine performance test, the vacuum gauge needle fluctuates rapidly at idle but stabilizes at higher rpm. This is indicative of:

A technician notes a high-pitched squealing noise from the engine on startup that diminishes after the engine reaches operating temperature. The MOST likely cause is:

If a four-stroke gasoline engine exhibits a puff of blue smoke only on initial startup, what is the MOST likely cause?

What is the significance of a "dead cylinder" during a running compression test?

When diagnosing an intermittent misfire on a direct injection engine, which of the following would be the MOST appropriate to inspect FIRST?

A vehicle with a DOHC (Dual Overhead Cam) engine is experiencing a loss of power and a rattling noise from the top end at all engine speeds. Which of the following should be inspected FIRST for potential failure?

A technician observes that an engine with sequential fuel injection initiates injector pulsing later than normal during cranking. This delayed injector timing is MOST likely due to:

When a four-stroke engine is hard to start when hot, but starts easily when cold, what should be suspected FIRST?

A technician is performing a cylinder leakage test. The air source is connected, and the technician hears air escaping from the throttle body. This is an indication of:

A technician finds that an engine is experiencing excessive oil consumption, but there are no external leaks. A compression test reveals good compression on all cylinders. What is the NEXT best step to diagnose this issue?

During an engine performance test, a technician notes that the engine has a rough idle, but smooths out at higher RPMs. The vacuum gauge shows a steady but lower than normal reading at idle. The MOST likely cause is:

An engine with a coil-on-plug ignition system is misfiring. The misfire does not move with a coil swap. What is the MOST appropriate next diagnostic step?

When diagnosing an overhead cam engine with variable valve timing, a technician notes that the engine performs poorly at all speeds and the timing marks are aligned at idle. This condition could be caused by:

A technician is diagnosing a direct injection engine that has a rough idle and a decrease in power. The fuel trim values are high at idle but normalize at higher RPMs. This is MOST likely due to:

An engine is producing a clicking noise that increases with engine speed. The noise is present when the engine is both cold and warm. The MOST likely source of this noise is:

If an engine exhibits a high-pitched whistle at idle that dissipates with increasing RPM, the MOST likely cause is: