The intake manifold runner control is an engine management component that is found on newer intake manifold designs. It is usually a motorized or vacuum actuated unit attached to the intake manifold, that controls the opening and closing of butterfly valves inside of the intake manifold runners. The unit will open and close the butterfly valves in order to provide maximum manifold pressure and flow at all engine speeds.
While an intake manifold runner is not necessary for engine operation, it does provide the engine with increased performance and efficiency, particularly at low engine speeds. When the intake manifold runner control fails, it can leave the engine without the increased performance, and in some cases even reduce performance. Usually a faulty intake manifold runner control will produce a few symptoms that can alert the driver of a potential issue.
1. Difficulty starting the engine
One of the first symptoms of a faulty intake manifold runner control is difficulty starting the engine. The intake manifold runner control is usually positioned when the vehicle is started. If the unit malfunctions, it may not position the butterfly valves correctly, which can lead to difficulty starting the engine. The engine may require more cranks than normal to start, or may require multiple turns of the key.
2. Engine misfires and decrease in power, acceleration, and fuel economy
Another symptom of a potential issue with the intake manifold runner control is engine performance issues. If the intake manifold runner control has an issue it can cause the vehicle to experience engine performance issues such as misfires, a decrease in power and acceleration, a decrease in fuel efficiency, and even stalling.
3. Check Engine Light comes on
An illuminated Check Engine Light is another symptom of a possible issue with the intake manifold runner control. If the computer detects an issue with the intake manifold runner control position, signal, or circuit, it will set off the Check Engine Light to alert the driver of the issue. The Check Engine Light can also be set off by a wide variety of other issues, so having the computer scanned for trouble codes.
While intake manifold runner control units are not found on all road going vehicles, they are becoming an increasingly common way for manufacturers to produce maximum engine performance and efficiency, particularly for smaller engines. It is also important to note that similar symptoms can also be produced by other engine performance issues, so it is recommended to have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the component manifold runner control should be replaced.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Intake Manifold Runner Control and was authored by Eduardo Ruelas.