Your vehicle’s throttle control cable is a fairly basic design playing an important role in the control and operation of your car’s engine. Connected to a spring loaded linkage on the side of your engine’s throttle body on one end and connected ultimately to your accelerator pedal on the other end, this simple component can create havoc when not functioning correctly. Many of today’s modern vehicles are now designed with electronic throttle control, which in many cases will be replaced by an electronic signal that is sent to the throttle body, which directly controls the position of the throttle body valve. For purposes of this article, however, we will focus on the cable controlled design.
As you press down on the accelerator pedal, the throttle control cable pulls on the linkage described above which is connected to what is often times referred to as a “butterfly valve” inside the throttle body. As this opens and closes, a sensor referred to as a Mass Air Flow Sensor monitors this change in air which relays this information to your car’s ECM, or Electronic Control Module. The ECM then increases the amount of fuel being sent to the injectors in order to maintain the proper air/fuel mixture.
The throttle control cable is comprised of an external housing and an internal wire that slides through it. This sliding movement transfers force to and from the accelerator pedal to the control linkage mounted on the throttle body housing. The housing of the cable is typically a rigid metallic skeleton with a vinyl inner liner and outer coating. The metallic skeleton can be constructed in various ways giving them different pliability characteristics depending on the design and routing of the cable specific to the vehicle model.
A cable wound like a coil is a design in which the metallic strands are wound around the housing like a coil spring. This type of design is much easier to bend and route through areas requiring curves and turns, however they are more likely to bind and compress which can cause functionality problems. Cables that are structurally designed to run straight (lengthwise) down the cable. This type of design is not as prone to binding and are much less pliable.
1. Improper cable adjustment and slow acceleration response
When there is excess slack or the cable is too tight, this can cause intermittent delays in throttle response relative to pressing down on the accelerator pedal. This can also result in the opposite effect as well, in that the excess slack can create a delayed throttle return response. This can cause more throttle to be applied unintentionally, creating a dangerous situation.
2. Dirty or frayed cable
When the cable is dirty, many of the same effects of too much slack (noted above) can also be experienced due to the cable occasionally sticking in certain positions. When the internal wire of the cable is frayed or the individual wires are broken, this can cause an improper response or complete lack of response to acceleration when the gas pedal is pressed.
3. Cruise control not working properly
Other symptoms can include problems with the cruise control functioning properly if your vehicle is equipped with this feature. Because the cruise control functionality is operated via the same throttle control cable, you may also notice intermittent delays in cruise control working or maintaining a consistent speed when engaged.
Changing this cable can involve a bit of time, knowledge, and precision in terms of routing properly. When improperly routed, catastrophic failure can result causing uncontrollable throttle response. Due to the importance of safety relative to it’s proper functionality, repairing or changing this cable should be performed by a qualified mechanic, such as one from YourMechanic.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Throttle Control Cable and was authored by Jeff Engstrom.