QTR-1A with Qik 2s9v1

Could you please help with the following problem?
I’m using an Arduino Uno R3 with a QTR-1A sensor, Qik2s9v1 motor controller and a 5v geared motor.
When the motor is idle, the QTR-1A detects different values to when the motor is running.
For example:

Sensor readings when Motor idle:

Sensor readings when Motor running:

No part of the setup is moving except for the motor spindle (which is not yet attached to anything).
The sensor is stationary inside a closed box and is always pointing at the same black reflective line on a white piece of paper.

Could you please help me understand what the problem could be and how to fix it?
I was wondering if this could be caused by noise but the motor is already a low noise version (with capacitors).
Also, would the digital version of this sensor be any different?

Thanks in advance,

Hi, Paul.

Can you post your full program and some pictures of your setup? How is everything connected?

- Ben

Hi Ben,
Thanks for your reply, since your post I found that the problem was my fault.
The power supply was not sufficient, so when the motor pulled power it lead to a too little voltage on the rest of the circuit.
Sorry for that!
Thanks, Paul