Solutions for Engine Vibration After Fuel Injector Cleaning
3 Answers
The reason for engine vibration after fuel injector cleaning is: It's quite normal to experience vibration after cleaning fuel injectors. The vehicle's ECU has a self-learning function that stores pre-cleaning fuel injection data. When injector nozzles are clogged with carbon deposits, the throttle valve automatically increases its opening to maintain idle air intake. After cleaning, the throttle valve still uses the clogged data, causing unstable idle and severe vibration due to excessive throttle opening. Simply resetting the throttle valve to factory settings can resolve this issue. The working principle of fuel injectors is: High-pressure fuel is pumped into the injector's supply port, creating pressure inside that acts on the injector's conical surface. When oil pressure exceeds the set value, the injector valve opens, spraying atomized fuel through small nozzles into the engine cylinder for combustion, driving piston reciprocation.
After I last cleaned the fuel injectors, the car also shook badly. It turned out that the fuel injector seals had aged. Improper disassembly during cleaning caused vacuum leaks at the seals, disrupting the air-fuel mixture ratio. In such cases, it's recommended to thoroughly inspect the O-rings and gaskets on the fuel injectors - they often cause air leaks when aged or improperly installed. Additionally, cleaning agent residue stuck in the injector nozzles can lead to poor fuel atomization. It's best to let the engine idle for an extra half hour to allow the system to adapt. If problems persist, use a diagnostic tool to check real-time fuel injection data. I remember the mechanic also advised simultaneously checking the intake manifold gasket and mass air flow sensor, as leaks in these areas can also cause shaking, since the entire intake system is interconnected.
Shaking after cleaning the fuel injectors is mostly an adaptation issue. The newly cleaned injectors deliver more fuel than when they were clogged with carbon deposits, but the car's computer still controls them based on the old parameters—like wearing old-sized clothes after suddenly losing weight. When I handle this myself, I disconnect the negative battery terminal for 5 minutes to reset the ECU, allowing the computer to relearn the air-fuel ratio. If it still shakes, check the spark plug gaps. Last time, I found one spark plug in the four cylinders was wet with residual cleaner, and replacing it fixed the issue. Don’t forget that cleaning can flush carbon deposits into the combustion chamber; in this case, a high-speed drive to burn off the carbon works quite well.
