This question uses the word LEAST. For this question, look for the choice that would LEAST LIKELY fit the described situation. Read the entire question carefully before choosing your answer. A customer complained that the engine has spark knock or detonation during rapid acceleration or when driving up a hill. Which of the following is the LEAST likely cause? a. Missing air cleaner cold air hose b. Carbon buildup in the combustion chambers c. Lack of sufficient exhaust gas recirculation (EGR) flow d. Pinched or restricted fuel return line
Pinched or restricted fuel return line is the LEAST likely cause for spark knock or detonation because it is a fuel related issue and will not cause a lean condition, which is a fuel related cause for detonation. The other three choices can all cause detonation or spark knock.
