Understanding and Resolving Steering Jerks when Lifting a Car with EPS

Have you ever lifted the front end of a car with an Electric Power Steering (EPS) system and observed the steering wheel jerking unexpectedly when the engine is turned on? This phenomenon can be attributed to several components and factors within the steering system. Let's delve into the details of this happening and how to resolve it.

Components and Factors Causing the Jerk

The jerking movement of the steering wheel during these conditions is often caused by a combination of issues related to the electric power steering motor, the steering column and shaft, the steering rack, suspension components, and potential issues with steering angle sensors and software or calibration problems.

The Electric Power Steering Motor

EPS systems utilize an electric motor to assist with steering. When the motor is activated while the vehicle is lifted, it may cause the steering wheel to move unexpectedly. This is due to the lack of load on the front wheels, which leads to no resistance for the motor to work against. Without feedback from the wheels, the motor behaves erratically, causing the steering wheel to jerk.

The Steering Column and Shaft

Any play or looseness in the steering column or shaft can result in unwanted movement of the steering wheel. When the vehicle is lifted, the suspension geometry changes, which can exacerbate this play and further contribute to the jerking steering sensation.

The Steering Rack

The steering rack translates the rotational movement of the steering wheel into lateral movement of the wheels. If the rack is worn or has internal binding, it can cause the steering wheel to jerk unpredictably. It's important to check the rack for any signs of wear or damage to prevent such issues.

Suspension Components

Lifting the front end of the car changes the suspension geometry. Any loose or worn suspension components, such as tie rods or ball joints, can lead to unexpected movement in the steering system. Ensuring that all these components are in good condition can help prevent steering jerks.

The Steering Angle Sensor

This sensor provides feedback to the EPS system about the position of the steering wheel. If the sensor is malfunctioning or calibrated incorrectly, it could cause the EPS to react incorrectly when the engine is started. Regular inspection and calibration of the steering angle sensors are crucial for maintaining a smooth driving experience.

Software or Calibration Issues

The EPS system relies on software algorithms to determine the appropriate level of assist based on the steering angle and vehicle speed. If there is a software glitch or calibration issue, it could result in erratic behavior when the vehicle is lifted. Updating the software and recalibrating the system can help resolve these issues.

How to Resolve the Issue

In summary, the jerking movement of the steering wheel is likely caused by a combination of issues related to the electric power steering motor's response to the lack of load, play in the steering components, potential issues with sensors, and software or calibration problems. To resolve this issue, it's advisable to:

Inspect the steering and suspension systems for any wear or damage. Check the EPS motor and ensure there is no play in the steering column and shaft. Examine the steering rack for wear or binding. Verify the condition of suspension components like tie rods and ball joints. Check and calibrate the steering angle sensor. Ensure the software and calibration of the EPS system are up to date.

By addressing these components and factors, you can prevent the jerking steering movement and ensure a smooth driving experience.