Variable Tumble Control System (VTCS) Operation Inspection

1. Connect scan tool to DLC-2. Access ECT PID. Ensure ECT is 149°F (65°C) or less. Start engine. VTCS shutter valve actuator rod should be pulled. If rod is pulled, go to next step. If rod is not pulled, inspect following:
   • VTCS shutter valve actuator.
   • VTCS delay valve.
   • VTCS chamber.
   • VTCS solenoid valve.
   • Vacuum hoses.
   • Wiring harness and connectors between PCM, VTCS solenoid valve and main relay.

   Repair or replace wiring harness or components as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.

2. Select RPM PID. Inspect VTCS shutter valve actuator rod operation. See VTCS SHUTTER VALVE ROD OPERATION (MIATA, PROTEGE & PROTEGE5)  table. If rod operation is not as specified, check following:
   • VTCS shutter valve actuator
   • VTCS delay valve
   • VTCS chamber
   • VTCS control solenoid valve
   • Vacuum hoses
   • Wire harness and connectors between PCM terminal No. 73, VTCS solenoid valve and main relay.
   VTCS SHUTTER VALVE ROD OPERATION (MIATA, PROTEGE & PROTEGE5)
   
   

   Application - Engine RPM		VTCS Shutter Valve Actuator
   Miata
   Less Than 3500		Operate
   More Than 3500		Does Not Operate
   Protege & Protege5
   Less Than 3000		Operate
   More Than 3000		Does Not Operate

For system testing, see appropriate SELF-DIAGNOSTICS article.