Chevrolet Trailblazer engine shakes at idle when cold and in drive, vibrations cease when out of gear or warmed up on Chevrolet Trailblazer

Some Chevrolet Trailblazer owners report experiencing engine shaking at idle when cold and in gear, with vibrations ceasing when out of gear or warmed up. This issue may be attributed to several factors, including engine mounts that have compressed over time, allowing vibrations to transfer into the vehicle's chassis and body; replacing these mounts with GM mounts is recommended for a long-term solution. Additionally, worn CV joints can contribute to shaking at idle if they are failing, as they are responsible for transferring power from the engine to the wheels. Engine misfiring is another common cause, often linked to faulty timing or worn timing belts or chains, particularly after significant engine work. Furthermore, some owners may experience vibrations due to the natural frequency of the system, where the engine's excitation frequency matches its natural frequency, causing noticeable vibrations. It is advisable for owners to have these components checked or replaced to effectively resolve the shaking issue.