What causes the Cadillac CT6 to shake during cold starts?
3 Answers
Here are the reasons why the Cadillac CT6 shakes during cold starts: 1. Insufficient engine temperature: When starting a cold engine, the temperature inside the engine is similar to the surrounding environment, which is not ideal for engine operation. In low temperatures, fuel atomization is poor, leading to reduced ignition energy and affecting performance, causing the car to shake. This phenomenon occurs more frequently in winter, so parking the car in a garage during cold weather can help alleviate engine shaking. 2. Incorrect air-fuel mixture ratio: During a cold start, the engine oil viscosity is high, and various components are not fully lubricated, making it easy for the air-fuel mixture ratio to be inaccurate. The car's computer may misjudge, reducing power output and causing shaking. 3. Carbon buildup in the engine: Carbon buildup is one of the main reasons for shaking during cold starts. Due to varying driving conditions and habits, different levels of carbon deposits can form on the valves and intake pipes, making cold starts difficult. This can also lead to insufficient power or even stalling while driving. If carbon buildup is severe, it should be cleaned promptly. If you cannot resolve it yourself, visit a 4S store for professional assistance.
When I drove the old CT6, I also encountered this issue. The mechanic told me there are several common reasons for cold start shaking: First, the engine mounts have aged and hardened. The rubber pads become especially brittle in winter, reducing their cushioning effect and allowing vibrations to reach the cabin. Second, there's excessive engine carbon buildup. The fuel injected by the injectors gets absorbed by the carbon deposits, making the air-fuel mixture too lean and causing rough idling. Third, the spark plugs have degraded in performance, especially the factory-installed ones after 40,000–50,000 kilometers, leading to inefficient ignition in cold temperatures. Thick engine oil is also a culprit—its poor flow in cold weather increases engine friction noise. Additionally, insufficient fuel pump pressure, particularly after refueling at small gas stations, can cause fuel delivery lag during cold starts, resulting in shaking. Later, I replaced the engine mounts and spark plugs, and the situation improved significantly.
Last time my colleague's CT6 started shaking like a massage chair in the morning. We focused on checking three areas with noticeable results: The fuel system issue was the main cause, especially slight clogging of the fuel injectors. Poor gasoline atomization during cold starts leads to incomplete combustion and vibration. Then there's the ignition system - aging or dampened rubber sleeves on ignition coils, or enlarged spark plug gaps can cause cylinder misfires. Also, don't overlook fuel quality issues. Water vapor mixed in the fuel tank can freeze and clog the filter screen, especially since ethanol gasoline tends to absorb more moisture. We recommend trying two tanks of 95-octane gasoline or adding legitimate fuel additives.
