A Technician Is Testing a Fuel Injection System with a Scan

question 19

Multiple Choice

A technician is testing a fuel injection system with a scan tool. While the engine is running in closed loop, he loosens a vacuum hose to create a small vacuum leak. Initially the STFT rises and the LTFT remains unchanged. After a few minutes the STFT returns to near zero and the LTFT rises. This test proves that ______.

• A)the system is running rich
• B)the system is running lean
• C)the O₂S sensor is faulty
• D)the system is working normally

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Definitions:

Normal Approximation

A method used in statistics to approximate a binomial distribution with a normal distribution when the sample size is large and the probability of success is not too close to 0 or 1.

Cumulative Binomial Probabilities

The sum of probabilities of achieving a given number of successes in a fixed number of Bernoulli trials.

Relative Frequency

The ratio of the number of times a specific value or event occurs to the total number of occurrences in a given dataset.

Population

The entire group of individuals or instances about whom the research is concerned.