SMA ON IFR FLT PLAN HAS ALTDEV AND MANIFOLD PRESSURE GAUGE FAILURE.

Narrative

DEPARTED EEN IFR FOR TEB. ICING OCCURRED AT 3 TIMES DURING THE FLT; REQUIRING EITHER A CLB OR DSCNT. THE WIND WAS STRONG WITH A SIGMET ISSUED FOR MODERATE TO SEVERE TURB AND LOW LEVEL WIND SHEAR. THE PERSON I WAS FLYING WITH OWNED THE ACFT WE WERE IN AND IS ALSO INST RATED. HE WAS PIC OF THE WHOLE FLT. AT TIMES WE HAD ALTDEVS OF 600- 300 FT. PARTLY DUE TO THE PIC'S PLTING TECHNIQUE BUT MOSTLY DUE TO THE CONDITIONS. SEVERAL TIMES CTLRS ASKED US ABOUT OUR ALT OR JUST GAVE US AN ALTIMETER SETTING. JUST OVER THE HUDSON RIVER; OR THEREABOUTS; THE MANIFOLD PRESSURE GAUGE FAILED. THIS HAD NO BEARING ON THE OUTCOME OF THE FLT. DSNDING TO TEB WE BROKE OUT AT 3100 FT MSL AND WERE HIT WITH SEVERE TURB WHICH MADE CTL VERY DIFFICULT. SEVERAL TIMES WE WENT THROUGH THE APCH BUT WERE IN VFR CONDITION AT THE TIME. WE LANDED AT TEB WITHOUT INCIDENT. THE PLT WAS SHAKEN UP AND I DIDN'T LOOK FORWARD TO RETURNING UNLESS CONDITIONS IMPROVED. A MECH AT FBO LOOKED AT THE ACFT TO MAKE A DIAGNOSIS AND FIX THE MANIFOLD PRESSURE GAUGE.