What are the reasons for the Buick GL8 shaking during acceleration?
4 Answers
Buick GL8 shaking during acceleration can be attributed to the following reasons: 1. Poor ignition: After driving a certain mileage, the ignition capability of the spark plugs decreases. During acceleration, weak spark plug firing can lead to poor combustion and shaking. 2. Insufficient fuel pressure: Use a fuel pressure gauge to check the gasoline pressure. Observe whether the fuel pressure keeps up during rapid acceleration. If not, inspect the fuel pump and fuel filter. 3. Poor fuel injection: Check whether the fuel injectors are spraying fuel properly and whether there is poor atomization or insufficient fuel injection. If so, clean the fuel injectors. If the problem persists after cleaning, replace them. 4. Incorrect ignition timing: Ignition timing controls the firing moment of the spark plugs. Use a computer to check whether the signals from the camshaft position sensor and crankshaft position sensor are normal, as well as whether the ignition timing is correct.
Just finished dealing with the same issue on a GL8, here are my findings. Fueling-related shaking is most commonly caused by ignition system problems, such as excessive spark plug electrode erosion leading to overly large gaps, or aging ignition coils resulting in misfires in certain cylinders. Yesterday's vehicle had a cracked ignition coil on cylinder 3, causing a cylinder cutout during hard acceleration that made it shake like sitting on a massage chair. Next are fuel system issues - clogged fuel injectors can cause an overly lean air-fuel mixture, while insufficient fuel pump pressure can lead to fuel starvation and shaking when flooring the accelerator. An often overlooked point is the engine mounts; when the rubber deteriorates, engine movement during acceleration becomes noticeably transmitted to the cabin. Finally, a reminder to GL8 owners: this model's transmission valve body is particularly sensitive. If accompanied by gearshift jerks, focus on checking transmission fluid condition and solenoid valve data streams. My advice: don't guess blindly - connect an OBD scanner to read misfire rate data for the most accurate diagnosis.
Having repaired Buicks for 15 years, I can say that acceleration shudder in GL8s is mostly combustion-related. First check if the idle is stable—if it shakes at idle too, the engine mounts might be completely worn out, making body movement more noticeable during hard acceleration. Worn spark plugs typically cause strong jerking during low-speed acceleration, especially when climbing hills fully loaded. Another common issue is a dirty air filter restricting airflow and throwing off the air-fuel mixture. Wheel imbalance causes vibration at specific speed ranges (usually 80-100km/h). Warped brake rotors won't cause shaking during acceleration, so that's easy to rule out. My advice: start with inexpensive checks—inspect spark plugs for wear, examine ignition coil boots for arcing, then test fuel pressure. These three steps solve 80% of cases.
Last week, I encountered the same issue while driving the company's GL8 on the highway. When I pressed the accelerator deeply, I felt vibrations in both the steering wheel and the seat, which disappeared upon releasing the throttle. Later, an inspection revealed that the right engine mount rubber pad was completely cracked. The aging rubber had lost its cushioning effect, causing the engine's power to be directly transmitted to the frame. Additionally, three spark plugs were found with gaps exceeding the limit. The mechanic mentioned that this V6 engine in the Buick has high ignition requirements. He also advised checking for carbon buildup in the throttle body, as excessive deposits could lead to a mismatch between throttle commands and air intake. At the time, I spent over 2,000 yuan at the dealership to fix the problem, primarily replacing the engine mount and all six spark plugs.
