Auto tech exam

Most engines have a spark duration of approximately ____ milliseconds.

1.5

The ideal or stoichiometric ratio of air to fuel (by weight) is ___ in a gasoline engine.

14.7

Spark plug firing voltage should normally be ___.

7 to 13 kV

A throttle position sensor has ___.

A 5-volt reference input terminal.

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 only

Technician A says white or grayish powdery deposits on secondary cables at the point where they cross or near metal parts indicate the 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 only

Technician A used the snapshot function of his scan tool to record serial data during a road test that can be transferred and displayed on a PC. Technician B uses the snapshot feature of his scan tool to record the sensor data and conditions leading up to the vehicle setting a DTC. Who is correct?

A only

Two technicians are discussing OBD- ii Monitor readiness status. Technician A says that the vehicle must be driven through a drive cycle that includes several minutes of idle, low-speed cruise, medium-speed cruise, and deceleration before all monitors can be performed. Technician B says all monitors can be performed in five minutes of fast idling. Who is correct?

A only

Oxygen sensor monitors are being discussed. Technician a says the system monitors the sensor response time as the system cycles lean-rich-lean. Technician B says that at certain times the monitor varies the fuel delivery and checks for heated oxygen sensor response. Who is correct?

Both A and B

Resistor-type spark plugs are being discussed. Technician A says the resistor increases the plug firing voltage. Technician B says the resistor helps reduce ratio frequency interference [RFI], which can interfere with, or damage, ratios, computers, and other electric accessories, such as GPS systems. Who is correct?

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?

Both A and B

Technician a test a MAF sensor with a scan tool by watching for erratic changes in flow while the engine idles. Technician B checks a MAF sensor by tapping it lightly with the handle of a screwdriver while watching the waveform on a lab scope. Who is correct?

Both A and B

Two technicians are discussing IAT sensors (intake air temperature). Technician a says The IAT sensor is an integral part of the mass airflow sensor (MAT). Technician B says the IAT is a discrete sensor located in the intake air passages or air cleaner assembly. Who is correct?

Both A and B

Two technicians are discussing testing switch type sensors. Technician A uses an ohmmeter. Technician B uses a voltmeter. Who is correct?

Both A and B

Two technicians are disgusting waste spark type ignition systems. Technician a says that half of the spark plugs in the system fire and reversed polarity [from the ground electrode to the center electrode]. Technician B says that the two spark plugs are connected in series with the coil. Who is correct?

Both A and B

Which of the following is NOT an advantage of an electric spark control system?

It allows lower compression ratio engines to be equally as efficient as higher compression ration engines

Which of the following is NOT the location of the ignition module?

On the steering column, behind the ignition switch

Which of the following sensors is NOT used by the computerized ignition system to control ignition timing?

Oxygen sensor

One of the advantages of a coil-on-plug type ignition system is that it eliminates the need for ___.

Spark plug wires

Reach, heat range, and air gap are all characteristics that affect the performance of which ignition system component?

Spark plugs

Which of the following is NOT used in testing engine sensors?

Test light

The injector pulse width is ___.

The amount of time the injector opens and sprays fuel

The ignition coil is essentially a pulse ___.

Transformer

The vehicle speed sensor is typically mounted on the ___.

Transmission

A defective EI coil may cause cylinder misfiring.

True

A misfire is also called incomplete combustion.

True

An ignition module may be damaged due to a poor electrical ground circuit.

True

Because air/fuel ratio sensors produce a signal only half their current output has been processed by the PCM, they cannot be tested with a voltmeter or lab scope.

True

Port fuel injection systems have a throttle plate assembly, but fuel never passes by the plate.

True

On an OBD-ii vehicle, the DLC connector is located ___.

Under the dashboard, within arms reach of the driver

An oscilloscope shows electrical ___ changes over a given period of time.

Voltage

Which of the following components is part of the primary ignition circuit?

Ignition switch

Leaner air/fuel mixtures ___.

Increase the electrical resistance inside the cylinder and increase the required firing voltage

Catalytic converter monitors are being discussed. Technician a says that if the converter is working, the downstream signal frequency should mirror the upstream sensor. Technician B says that the downstream sensor should provide a low frequency voltage signal. Who is correct?

B only

Diagnostic trouble codes are being discussed. Technician a says a P0442 is a manufacturers code and means different things, depending on what manufacturer built the car. Technician B says that a P0304 Code is a universal code that means the same thing no matter what manufacturer built the car. Who is correct?

B only

Engine operating modes are being discussed. Technician A says that when the engine is in closed-loop mode, the PCM monitors sensor inputs, then adjusts the timing, air fuel ratio, and emission controls. Technician B says the system will switch into open loop when the throttle is fully opened or the oxygen sensors cool down during idle. Who is correct?

Both A and B

Which of the following jobs is NOT a function of the ignition system?

Engaging the starter motor

Which of the following statements about carbon tracking is NOT correct?

Carbon tracking usually occurs in the primary ignition circuit

A ___ Ignition system has one ignition coil per cylinder and also uses spark plug wires.

Coil near plug coil by plug

What sensor is used to detect engine misfire?

Crankshaft position

In a GDI system (gasoline direct injection) the injector sprays fuel into the ___.

Cylinders (combustion chamber)

The camshaft position sensor provides the PCM with data needed to control ___.

Ignition coil timing, fuel injector timing, and variable valve timing

A MAP sensor with a varying frequency output can be tested with a(n) ___.

DMM with a frequency function

A sensor with a bad ground connection will produce a lower than normal signal voltage.

False

Damaged spark plug threads in an aluminum cylinder head cannot be repaired the head must be replaced if the threads or damaged.

False

During the EVAP monitor vacuum pull-down test, the canister vent solenoid is held open.

False

On a coil-over-plug type ignition system, a faulty coil will affect two cylinders.

False

The MAP sensor used on a turbocharged engine is calibrated the same as a MAP sensor for a nonturbocharged engine.

False

The engine coolant temperature sensor helps to control all the following EXCEPT:

Fuel pressure

When the cylinders are deactivated on a displacement on-demand system, ___.

Half of the cylinders continue to fire normally