What symptom would suggest that there are leaking intake pipes in an engine?

An engine running rough at low RPM can indicate multiple issues, but when it comes to leaking intake pipes, this symptom becomes significant. Leaking intake pipes can disrupt the air-fuel mixture entering the engine, leading to an imbalance. At low RPM, the engine's power and torque demands are relatively low, and any irregularities in this mixture will be more noticeable.

If intake pipes are leaking, they may allow unmeasured air to enter the combustion chamber. This can result in a lean mixture, which makes the engine run unevenly or rough, particularly at lower speeds where engine load and demands are less stable. Thus, the rough running at low RPM becomes a clear indicator that the intake system may not be functioning correctly.

In contrast, a smoothly running engine at high RPM does not reflect issues with the intake pipes, as higher engine speeds can often mask slight variances in performance. A silent engine may suggest other issues, such as lack of fuel supply or problems with the exhaust system, while excessive smoke typically points to oil burning or fuel problems rather than direct intake issues.