Why does the car shake violently after replacing the fuel injectors?
3 Answers
After replacing the fuel injectors, the car shakes violently because the throttle body is too dirty. Dirty throttle body and excessive carbon buildup in fuel injectors: When a car has been driven for a certain mileage, a dirty throttle body can cause the throttle valve to not close properly or the idle stepper motor to get stuck, both of which can lead to excessively high engine idle speed. Additionally, carbon deposits generated during engine operation can also cause vehicle shaking, especially when starting the car. The engine may shake more violently than usual, and in some cases, it might not start on the first attempt. Therefore, when the vehicle experiences shaking, the throttle body and fuel injectors should be checked first. If the throttle body is found to be too dirty or the fuel injectors have excessive carbon buildup, they should be cleaned promptly. Steps for cleaning the throttle body: If there is a plastic heat shield cover on the engine, remove it. Disconnect the air ducts around the throttle body and note their positions. The side of the throttle body near the combustion chamber is usually dirty, with black carbon deposits, which is the main area to be cleaned. Cleaning the throttle body primarily involves removing carbon deposits, using specialized cleaning solutions or carburetor cleaners. These cleaning agents can be harmful to humans, so gloves and a mask should be worn during cleaning.
I've encountered this situation before. After replacing the fuel injectors, the car shakes violently mostly because the new parts weren't installed properly or there are compatibility issues. If the fuel injectors aren't sealed well, it can cause fuel leaks or uneven fuel supply, making the engine shake. The ECU needs to relearn the new parameters; otherwise, the computer will still operate based on the old injector settings, leading to incorrect fuel injection. I once helped a friend fix this issue - it was because we forgot to reset the ECU by disconnecting the power, and the car shook like an earthquake upon starting. Also, check if the connectors are properly plugged in and if there are any short circuits in the wiring. Don't force the car to drive when it's shaking, as it can easily cause misfires or damage the engine. It's recommended to use a diagnostic tool to read fault codes, such as P0300 misfire codes, to quickly locate the issue. Take it to a professional shop for rechecking—they can calibrate the injectors or adjust the ECU to ensure smooth operation.
My car has been shaking non-stop since the last fuel injector replacement, which made me quite nervous. After checking forums, common causes include poor quality of new injectors, loose installation, or injector models not matching OEM standards. I tried inspecting the connectors and seals myself and found a leaking spot on one, but the issue persisted after fixing it. Later, the mechanic mentioned that the ECU wasn't reset and advised idling for a few minutes after startup to let the computer relearn. The shaking causes noticeable power instability while driving, especially at low speeds where it feels like the engine might stall—pretty dangerous. Here's a tip: disconnecting the battery for a few minutes and restarting the car often helps. If shaking continues, check for related issues with spark plugs or the air system. Don't cut corners—take it back to the repair shop for comprehensive testing and resolution.
