As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MFR- AFTER NR 2 ENGINE START WHEN BLEED WAS TURNED ON, THE COCKPIT AND CABIN BEGAN TO FILL UP WITH AN ACRID HAZE. REMOVED AND REPLACED P2.5-P3 SWITCHING VALVE PISTON, RING AND INNER HOUSING. GROUND RAN AIRCRAFT, NO SMOKE OR SMELL NOTED. AIRCRAFT RETURNED TO SERVICE.