Symptoms of a bad Idle Air Control (IAC) valve
A damaged car's Idle Air Control (IAC) valve will often immediately make engine control more uncomfortable. The car will feel stuttering until the engine stalls while driving.
Because IAC valve controls and regulates engine idling rpm, the effect will be felt even greater when the car is in idling position, especially when the engine is under heavy load such as the A/C on, the headlamp lights on, or when the radiator fan rotates.
So, what are the symptoms that the engine will experience when the car's IAC valve is bad? The following article will explain the characteristics of a bad IAC valve that are often experienced both the symptoms caused and the physical condition of the IAC valve motor itself.
I. Symptoms on the engine when the IAC valve is going bad
A bad IAC valve will cause the engine to run imperfectly and be challenging to control. The following are the symptoms of a bad IAC valve in the engine.
1. The engine rpm is unstable
The first symptom that often occurs from a bad IAC valve is that the engine rpm is unstable and goes up and down frequently, especially when the engine is at idling rpm.
Yes, when the rpm is idling, the engine will shake because the engine speed suddenly rises and falls repeatedly. After the rpm goes down, the rpm then goes back up again without us stepping on the gas pedal. This condition will continue until repairs are made.
2. The engine rpm goes down and drops when running slowly
The next symptom that indicates a bad IAC valve is the decrease in engine rpm when the car is moving slowly.
The condition of idling rpm goes up and down will be more pronounced when the car has started to go slowly. Even in some conditions, there is a significant decrease in engine rpm. It can make the car engine stalls suddenly while driving.
3. The engine often shuts down when idling, especially when the Air Conditioner (AC) is on
When the damage condition of the IAC valve is getting worse, it is not uncommon for the car engine to often turn off when idling, especially when the AC is on.
When the AC is on, the engine load will increase because the engine has to rotate the AC compressor. As a result, the engine idling rpm becomes unstable, and the engine turns off faster.
II. The characteristic of a bad IAC valve
In addition to the symptoms of a bad IAC valve that appear when the car is driven, here are the conditions that occur when the IAC is damaged:
1. The IAC pintle surface is worn and damaged
The most common characteristic of a damaged IAC valve is the pintle end surface and the Idle porthole worn and starting to erode.
The erosion of the surface on the pintle and the end of the idle porthole will make the position of closing the hole not tight so that air leaks can occur in that place. Air leaks will affect the overall idle rpm condition.
Read Also:2. Motor IAC valve short / Resistance value increases
In addition to the damaged pintle tip on the IAC valve motor, the next characteristic that causes the IAC valve to be damaged is the resistance value of the coil in the IAC motor, whose value has changed to be greater than the standard value allowed by the factory.
The greater the resistance value, the smaller the IAC pintle when it is open or closed.
3. Pintle stuck won't move
The last characteristic that is a sign that the IAC valve motor is damaged is that the pintle can no longer move forward and backward, aka jammed.
It often occurs because the pintle is exposed to dirt that often sticks on all over the pintle's body.