What Causes Unstable Idle Speed in Sedans?

[AshlynFitz]

Here are the explanations for the causes of unstable idle speed in sedans: 1. Fuel injector malfunction: Uneven fuel injection or poor atomization by the injector leads to an imbalance in power output among the cylinders. Common causes include: clogged injectors, poor sealing, or fuel being sprayed in a stream rather than atomized. 2. Fuel pressure issues: Low fuel pressure results in poor atomization or a stream-like spray of fuel, and in severe cases, only droplets are emitted, reducing the fuel quantity and making the air-fuel mixture too lean. High fuel pressure increases the actual fuel injection quantity, making the mixture too rich. 3. Incorrect fuel injection quantity: Faulty sensors or wiring can cause the control unit to issue incorrect commands, leading to improper fuel injection quantities, resulting in an overly rich or lean mixture, which is an indirect cause of unstable idle speed.