Why is my car idling going up and down?
Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor.
Is it normal for idle to fluctuate?
It actually is completely normal for the engine idle speed fluctuate a small amount. Gone are the days of a mechanically adjustable idle speed screw and a mechanical cable operated throttle.
What causes idle surging?
If an engine is not getting enough fuel (this is called “running lean”), due to fuel pressure (regulated by the fuel pump and regulator), restricted fuel injectors, a vacuum leak or really anything that throws off the fuel mixture going in to the engine, this can cause the surge.
What would cause a surging idle?
When to relearn the idle adjustment screw on an IAC?
If it looks like someone has messed with the idle adjustment screw perform the idle relearn procedure. Depending on the model you normally unplug the IAC after the engine is fully warmed up and adjust the idle screw until you reach base idle which is normally in the 700-750rpm range.
Why does my car idle all the time?
Erratic engine idle can be caused by various factors, but the most common and likely cause is a dirty or malfunctioning Mass Air Flow (MAF) sensor. This is a device found in fuel-injected cars and measures air flow so that the appropriate amount of fuel can be injected.
Why does an erratic idle set a MAP sensor code?
An erratic idle CAN set a MAP sensor code however which is why I mention it. The reason for this is because the MAP is in essence a vacuum gauge so if it’s gets strange readings from a fluctuating idle it can set a MAP sensor code.
What does hunting idle mean on a Honda?
The computer also fights them as it tries to maintain an idle using the IAC but it can’t keep up so you get a ‘hunting’ idle condition meaning that the idle fluctuates from high to low and it never levels out. This condition is often worse after the engine warms up.