Exam 24: Engine Performance Systems

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?

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?

A catalytic converter monitor DTC is set after detecting faults on ____________________ consecutive drive cycles.

Higher-octane fuels are easier to ignite and burn faster than low-octane fuel.

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

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

Higher compression ratios tend to speed up combustion.

The misfire monitor is necessary protect to the ____________________from melting during a continuous misfire.

A fault that comes and goes and is not always present is called a(n)____________________ fault.

A V-6 engine has an oxygen sensor in each exhaust manifold. How do you determine which one is B1 S1?

The first decision the computer makes in determining the best operating strategy is to determine the _____.

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

Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor and output status data at the instant the DTC was set. Who is correct?

A PCM that can learn the nominal range of inputs and outputs by monitoring them over a long period of time is said to be using ____________________ strategy.

The injector pulse width is the ______.

To read flash codes on an OBD I Chrysler-built vehicle, you must ______.

Technician A uses 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?

What is the DLC and where is it found in modern vehicles?

After ____________________ warm-up cycles without a fault, a DTC code is erased from active memory, but the DTC and the freeze frame data will be stored as a history code with freeze frame data until it is cleared.

Which of the following statements is not true?