BEECH KINGAIR 90 PLT HAS A TRACK AND HDG AND ALTDEV DURING CANOGA 8 DEP FROM VNY.

Narrative

I WAS CLRED TO DEPART VNY WITH A STANDARD SID CANOGA 8 DEP. PRIOR I HAD JUST FUELED AND SOMEHOW UNSLAVED AND 'SQUED' MY DG. I SET MY GPS TO THE FIRST FIX ON THE DEP. I WAS CLRED FOR TKOF. I STARTED TO TRACK MY COURSE WITH REF TO MY GPS. WHEN I REACHED THE 2.2 DME MARK ON THE DEP I TURNED TO WHAT I BELIEVED TO BE A HDG OF 210 DEGS. I CONTACTED SOCAL APCH AND SAW I HAD A LARGE ERROR IN MY COURSE ON MY GPS AND MY HDG ON MY DIRECTIONAL GYRO; AS I WAS FIGURING OUT WHY I BECAME DISTR AND CLBED THROUGH MY ALT OF 1700 FT. THE CTLR ADVISED THAT I WAS OFF MY ASSIGNED HDG. I DISCUSSED THE DIRECTIONAL GYRO WAS UNSLAVED AND OFF. I SLAVED THE DIRECTIONAL GYRO AND IT STARTED BACK TO THE CORRECT HDG. BY THIS TIME I OVERSHOT MY HDG BY ABOUT 70 DEGS. I STARTED TO CORRECT AND WAS THEN TOLD BY ATC I WAS CLRED TO CONTINUE A CLB AND DIRECT TO GMN; MY NEXT FIX. THE PROB WAS ALL CAUSED BY NOT SIMPLY CHKING MY DIRECTIONAL GYRO AS I LINED UP ON THE CTRLINE OF THE RWY. I WOULD HAVE SEEN THE ERROR ON THE GND AND CORRECTED WITH NO PROB. BECAUSE I DID NOT I BECAME OFF HDG AND ALT IN ONE ACTION.