Why does the Reiz have unstable idle speed?

[LukeFitz]

Here is a detailed introduction to the causes of unstable idle speed in the Reiz: 1. Excessive carbon buildup in the throttle. 2. Leakage in the intake manifold or various valves: This fault directly affects the quality of the fuel-air mixture and combustion efficiency. Possible leakage points include the intake manifold, vacuum tubes, charcoal canister valve, exhaust gas recirculation (EGR) valve, positive crankcase ventilation (PCV) valve, etc., which need to be inspected and repaired one by one. 3. Valve timing fault: Incorrect valve timing, improperly installed timing belt, excessive carbon buildup on intake and exhaust valves, broken valve springs, etc., can cause uneven air intake in each cylinder, leading to unstable idle speed. 4. Clogged three-way catalytic converter: A clogged three-way catalytic converter not only causes unstable idle speed but also results in insufficient power. 5. Fuel injector fault: Issues such as poor fuel atomization or clogged injectors require cleaning the injectors. 6. Low fuel pressure: Mainly check for clogged components like the fuel filter and fuel pump, or deformed fuel lines. 7. Engine misfire. 8. Excessive or insufficient ignition advance angle: Mostly caused by problems with various signal sensors, such as the air flow sensor, Hall sensor, knock sensor, coolant temperature sensor, etc., which need to be analyzed with a diagnostic tool.