What Causes Unstable Idle and Increased Fuel Consumption?

[Norman]

The reasons for unstable idle and increased fuel consumption are as follows: Various valve leaks: Intake manifold or various valve leaks. This type of fault directly affects the quality of the fuel-air mixture and combustion efficiency. Possible leak locations include the intake manifold, vacuum pipes, charcoal canister valve, exhaust gas recirculation valve, crankcase ventilation valve, etc., which need to be inspected and repaired one by one. Valve timing fault: Incorrect valve timing, improperly installed timing belt, excessive carbon buildup on intake and exhaust valves, broken valve springs, etc. If the intake air volume varies for each cylinder, it will result in unstable idle. Clogged catalytic converter: A clogged catalytic converter not only causes unstable idle but also leads to insufficient power. Fuel injector fault: Poor fuel injector atomization, clogged fuel injectors, etc., require cleaning the fuel injectors. Low fuel pressure: Mainly check whether components such as the fuel filter and fuel pump are clogged, and whether the fuel lines are deformed, among other faults.