you notice low vacuum readings only at high engine rpm. which is the most likely cause? a) valve train…

you notice low vacuum readings only at high engine rpm. which is the most likely cause? a) valve train malfunction b) vacuum leak c) incorrect cam or ignition timing d) exhaust restriction

you notice low vacuum readings only at high engine rpm. which is the most likely cause? a) valve train malfunction b) vacuum leak c) incorrect cam or ignition timing d) exhaust restriction

Answer

Brief Explanations:

A vacuum leak would cause low vacuum readings at all RPMs. Incorrect cam or ignition timing can affect vacuum but usually has broader - range symptoms. Exhaust restriction affects back - pressure more than just high - RPM vacuum. A valve train malfunction can specifically cause low vacuum only at high engine RPM as the valves may not be operating properly under high - speed conditions.

Answer:

A. Valve train malfunction