Why does my car keep idling up and down?
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.
Why does my Honda Civic idle up and down?
If your idling fluctuates up and down during cold start and goes away after operating temp is met, your Fast Idle Thermal Valve has backed out. If your idling fluctuates up and down during operating temp, then it is most likely the IACV. The MAF sensor measures the amount of air flowing through the throttle valve.
Why does a car vibrate while idling?
Motor Mounts. Motor mounts keep your engine attached to the car. Weak or broken mounts can’t hold the engine tight in the engine compartment and creates a vibration at idle. If the shaking subsides when the car is in Neutral, this could indicate the motor mounts are responsible for the vibrations.
What causes a Subaru Outback to run rough at idle?
These packs are fired by the engines computer at exactly the right time to provide the optimal ignition timing. If a coil pack goes bad, it’ll cause a misfire and rough idle condition. Really, your Outback will be running rougher at any RPM, but a misfire will be most pronounced at idle.
What causes an Audi A4 to idle rough?
A super lean running engine will often idle rough. The fuel injection systems job is to atomize the fuel into fine mist. If a fuel injector has an issue with this process, it will either let too much or too little fuel into the combustion chamber relative to the amount of air.
Why are my spark plugs not working on my Subaru Outback?
Spark Plugs – One of the absolute most common causes (if not the most common reason that your Outback may be misfiring) is the spark plugs. Although most modern vehicles use iridium spark plugs, they still need to be changed at the manufacturers recommended interval.
Why does my Chevy Cobalt have rough idle?
An internal combustion engine needs air, fuel, and spark in order to achieve ignition. When one or more of these variables is off it can lead to a rough idling condition. Most of the time the culprit is going to be the ignition system, although there are a myriad of other causes.