Ignition & Fuel Systems: Chapter 27

TRUE OR FALSE: All ignition system diagnosis should begin with a visual inspection.

TRUE

TRUE OR FALSE: An ignition control module may overheat if it is not securely mounted.

TRUE

TRUE OR FALSE: Detonation can cause physical damage to the pistons, valves, bearings, and spark plugs.

TRUE

TRUE OR FALSE: Insufficient timing advance or retarded timing at higher engine speeds could cause hesitation and poor fuel economy.

TRUE

TRUE OR FALSE:An ignition module may be damaged due to a poor electrical ground circuit.

TRUE

TRUE OR FALSE: Preignition is the same as detonation.

FALSE

TRUE OR FALSE: If a vacuum gauge shows a low but steady vacuum when the engine is at idle, the problem is a noncommon type.

FALSE

TRUE OR FALSE: The reluctor (or pole piece) of a magnetic pulse generator should be replaced as a maintenance item when engine spark plugs are renewed.

FALSE

TRUE OR FALSE: A misfire is also called incomplete combustion.

TRUE

TRUE OR FALSE: All ignition system problems will set a DTC in the vehicle's PCM and can be read with a scan tool.

FALSE

TRUE OR FALSE: Damaged spark plug threads in an aluminum cylinder head cannot be repaired. The head must be replaced if the threads are damaged.

FALSE

TRUE OR FALSE: EMI can be produced by the vehicle's primary ignition circuit.

FALSE

Possible causes for a no-start condition on a coil-over-plug EI engine are being discussed. Technician A says a faulty crankshaft sensor may prevent the engine from starting. Technician B says a shorted ignition coil may be the cause. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

a) A only

Technician A performs a cylinder performance test [power balance test] to determine which cylinder is misfiring. Technician B uses a vacuum gauge to pinpoint the misfiring cylinder. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

a) A only

Technician A removes plug wires by grasping the spark plug boot and gently twisting it off. Technician B uses a 13/16 in. deep thinwall socket to remove spark plugs. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

a) A only

Usually an engine is timed so that the number 1 spark plug fires several degrees _____. a) BTDC (before top dead center) b) ATDC (after top dead center) c) BBDC (before bottom dead center) d) ABDC (after bottom dead center)

a) BTDC (before top dead center)

Spark plug cables from consecutively firing cylinders should ______. a) cross rather than run parallel to one another b) run parallel rather than cross one another c) cross and run parallel to one another d) None of the answers is correct.

a) cross rather than run parallel to one another

Which of the following is not a common cause of preignition? a) faulty ignition coil b) incandescent carbon deposits in the combustion chamber c) faulty cooling system d) too hot of a spark plug

a) faulty ignition coil

While discussing EI service, Technician A says the crankshaft sensor may be rotated to adjust the basic ignition timing. Technician B says the crankshaft sensor may be moved to adjust the clearance between the pickup coil and reluctor on some EI systems. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

b) B only

While testing a coil in an EI ignition system, Technician A says an infinite reading means that the winding has zero resistance and is shorted. Technician B says the secondary winding in a waste spark (doubled-ended) coil should be checked by connecting the meter across the two secondary terminals. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

b) B only

Spark plug firing voltage should normally be ______. a) less than 3 kV b) 3 to 13 kV c) 7 to 13 kV d) None of the answers is correct.

c) 7 to 13 kV

During a coil output test, the firing line shown on the oscilloscope pattern should exceed ______ volts. a) 12 b) 350 c) 1,200 d) 35,000

d) 35,000

To minimize EMI interference, sensor wires should be routed away from _____. a) spark plug wires b) ignition coils c) distributor caps d) All the answers are correct.

d) All the answers are correct.

Which of the following statements is false? a) Carbon tracking may occur inside a distributor cap b) Carbon tracking indicates that high voltage has followed a low-resistance conductive path c) Carbon tracking may cause a misfire d) Carbon tracking usually occurs in the primary ignition circuit

d) Carbon tracking usually occurs in the primary ignition circuit

Waste spark EI systems are being discussed. Technician A says a high-resistance spark plug won't affect the firing of its companion spark plug. Technician B says improper spark plug torque can't cause an engine misfire. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

d) neither A nor B

Most engines have a spark duration of approximately _____ milliseconds. a) 0.5 b) 1.5 c) 5.0 d) 15.0

b) 1.5

TRUE OR FALSE: Gapping the spark plug is only necessary on used spark plugs. New spark plugs have their gaps set at the factory.

FALSE

TRUE OR FALSE: A bad sensor ground may cause the same symptoms as a faulty sensor.

TRUE

TRUE OR FALSE: A defective EI coil may cause cylinder misfiring.

TRUE

Technician A says white or grayish powdery deposits on secondary cables at the point where they cross or near metal parts indicate that the cables' insulation is faulty. Technician B says if the spark plug wire for #2 cylinder is damaged and the other wires look good, replace only the damaged wire. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

a) A only

The firing lines on an oscilloscope are all abnormally low. Technician A says the problem could be a faulty coil. Technician B says the problem could be a lean air/fuel mixture. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

a) A only

If the spark line is totally flat, is longer than 2 ms, and is less than 500 volts, there is a good chance that: a) the plug is not firing b) the air/fuel ratio is excessively lean c) there is high resistance in the spark plug wires d) the spark plug heat range is wrong for the engine

a) the plug is not firing

Technician A says large amounts of EMI can collapse the field in a coil and cause a plug to fire. Technician B says poor spark plug cable insulation may cause EMI. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

b) B only

On an oscilloscope, which section ends with the primary coil current off signal? a) intermediate b) dwell c) firing d) both "intermediate" and "dwell"

b) dwell

Which of the following problems is NOT caused by a misfire? a) lack of power b) high idle speed c) poor fuel economy d) excess exhaust emissions

b) high idle speed

Leaner air/fuel mixtures ______. a) decrease the electrical resistance inside the cylinder and decrease the required firing voltage b) increase the electrical resistance inside the cylinder and increase the required firing voltage c) increase the electrical resistance inside the cylinder and decrease the required firing voltage d) have no measurable effect on cylinder resistance

b) increase the electrical resistance inside the cylinder and increase the required firing voltage

The dwell period on a modern electronic ignition system ______. a) is fixed and does not change with engine RPM b) increases (lengthens) as engine RPM increases c) decreases (shortens) as engine RPM increases d) is required

b) increases (lengthens) as engine RPM increases

An ohmmeter connected to the leads of a pickup coil in a DI ignition system reads 14 ohms of resistance. The reading indicates that the pickup coil ______. a) is satisfactory b) is shorted c) is open d) has high resistance

b) is shorted

The air gap between the crankshaft position sensor (CKP) and the trigger wheel is measured with a(n) _____. a) wire gauge b) nonmagnetic feeler gauge c) inside micrometer d) dial indicator

b) nonmagnetic feeler gauge

A "cranks but does not start" problem on a waste spark type EI system is being diagnosed. When a spark tester is connected to each coil and the starter is engaged, there is no spark. Technician A says the crankshaft position sensor could be the problem. Technician B says the PCM could be the problem. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

A no-start condition on an EI system is being discussed. Technician A says to use a test spark plug to determine whether the problem is in the ignition system. Technician B says that if a noid light is connected to the injector harness and it pulses while the engine is cranked, the triggering unit for the primary ignition circuit should be okay. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

Crankshaft position sensors (CKP) are _____ type sensors. a) Hall-effect b) magnetic pulse generators c) both A and B d) neither A nor B

c) both A and B

Ignition coil testing is being discussed. Technician A uses an ohmmeter to measure primary and secondary resistance. Technician B uses an oscilloscope and a test spark plug to measure maximum coil output voltage. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

Technician A says a fouled spark plug can cause a misfire. Technician B says a bad coil can cause a misfire. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

Technician A says a loose ignition module mount can cause intermittent misfires or no-start conditions. Technician B says when installing a new ignition module, a small amount of heat conductive grease should be applied to the mounting surfaces. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

Test equipment for checking the primary circuit is being discussed. Technician A says a logic probe can be used. Technician B says a DMM can be used. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

While discussing an ignition problem displayed on a scope primary ignition pattern, Technician A says a worn distributor drive gear can cause an erratic transistor ON signal. Technician B says if there are erratic voltage spikes at the transistor ON signal, the ignition module may be faulty. Who is correct? a) A only b) B only c) both A and B d) neither A nor B

c) both A and B

Which of the following is NOT the location of the ignition module? a) inside the distributor b) underneath the coil packs c) on the steering column, behind the ignition switch d) integral with the PCM

c) on the steering column, behind the ignition switch

Which of the following is NOT a cause of spark knock? a) excessively advanced ignition timing b) engine overheating c) excessively lean air/fuel mixture d) high-octane fuel

d) high-octane fuel