Suspect of Magnetic disturbances

Hi, I´m making a project which includes, among other stuff, a mid-size dc motor an a microcontroller. The question that I have is, due to the lack of space, the pcb is too near, almost touching, the motor and the micro is really near it. Does this condition cause some probles in signal integrity? Cause Im experiencing noise, but I don't know the source, I´ve put the decoupling caps but some times the noise disturb, not always, but sometimes. Any suggestions, comments or ideas? thanks!!

A motor's case provides significant magnetic shielding, though induction cannot be ruled out as a source of noise, particularly of there are untwisted wires driving the motor and/or signal conductors near the motor and/or its power wiring. The more likely source of noise is from the motor's brushes (if applicable to your motor). A capacitor connected close to the motor's terminals is often used to suppress brush noise (say .22uF). It is a good idea to twist the two wires together that drive the motor.