| A-8 Engine Performance Certification Practice Test Answers |
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| 6.
Answer A is wrong. After the first reading oil is injected into the cylinder. If the reading increases then the piston rings are worn. Answer B is wrong. Low manifold vacuum is a symptom of weak compression. Answer C is wrong. After the first reading oil is injected into the cylinder. If the reading stays the same it is most likely burned valves. With the pattern shown in the illustration it is most-likely retarded camshaft timing. Answer D is correct. With the pattern shown in the illustration, it is most-likely retarded camshaft timing. Return Learn more about interpreting compression test results. |
| 7.
Answer A is wrong. If the gauge reads (17-22 in Hg) this indicates a normal running engine. Answer B is wrong. If the gauge reads low (15-20 in Hg) this indicates low valve or ignition timing, leaking manifold gasket, low compression, leaking carburetor, or stuck throttle valve. Answer C is correct. If the gauge readings fluctuate between (15 and 20 in Hg) this indicates a stuck valve or an engine miss. Answer D is wrong. If the gauge reading drops slowly at an idle this indicates a clogged or blocked exhaust. Return Learn more about interpreting vacuum gauge test results. |
| 8.
Answer A is wrong. A stuck open EGR valve will cause an engine to stumble or stall. Answer B is wrong. A stuck closed EGR valve will cause harmful engine detonation. Answer C is wrong. Neither technician is correct. Answer D is correct. Neither technician is correct. Return Learn more about NOx emissions and the EGR valve. |
| 9.
Answer A is correct. A leaking fuel injector causes a rich fuel mixture. A rich fuel condition causes black colored smoke to emit from the tailpipe. Answer B is wrong. Worn rings cause blue gray colored smoke. Answer C is wrong. A blown head Gasket causes white gray smoke. Answer D is wrong. Leaking valve seals would produce blue gray smoke. Return Learn more about troubleshooting exhaust color. |
| 10.
Answer A is wrong. A burned exhaust valve will cause the needle on the vacuum gauge to fluctuate. Answer B is wrong. Late ignition timing will cause a low vacuum reading between 10Hg and 15Hg. Answer C is wrong. A blown head gasket will cause an engine to overheat and allow coolant to enter the combustion chamber. This will result in white/grey smoke. Answer D is correct. If the needle drops steady during acceleration there's a restriction in the exhaust. This is reading is most likely caused by a clogged catalytic converter. Return Learn more about troubleshooting a catalytic converter. |
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