ASE4 General Engine Diagnosis

Question 1

A customer complains of a rough idle that disappears at higher RPMs. Which tool is BEST used to identify a misfiring cylinder?

Accepted Answer

Scan tool with misfire counters

Answer

Vacuum gauge

Answer

Compression tester

Answer

Fuel pressure gauge

Question 2

A cylinder power balance test shows that shorting cylinder #3 causes no RPM drop. This indicates:

Accepted Answer

That cylinder is not contributing to engine power

Answer

That cylinder is producing too much power

Answer

That cylinder has a lean condition

Answer

The ignition timing is advanced on #3

Question 3

Low compression on two adjacent cylinders most likely indicates:

Accepted Answer

A blown head gasket between those cylinders

Answer

Worn piston rings

Answer

A faulty intake manifold gasket

Answer

Excessive valve clearance

Question 4

When performing a cylinder leakage test, air is heard escaping from the throttle body. This indicates:

Accepted Answer

A leaking intake valve

Answer

A leaking exhaust valve

Answer

Worn piston rings

Answer

A cracked piston

Question 5

An engine has good compression but produces blue smoke at startup that clears after a few minutes. The MOST likely cause is:

Accepted Answer

Leaking valve stem seals

Answer

Worn piston rings

Answer

A cracked cylinder head

Answer

A rich fuel mixture

Question 6

A technician connects a vacuum gauge and observes a steady low reading of 12 in-Hg at idle. This MOST likely indicates:

Accepted Answer

Late ignition timing

Answer

A leaking head gasket

Answer

A restricted exhaust

Answer

Worn piston rings