LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 1988 >> 4Runner Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Feedback Carburetor System >> Testing >> Air Suction (As) System
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Air Suction (As) System

  1. Check all hoses, tubes and connections for cracks, kinks, damage or looseness. Repair as necessary. Ensure engine coolant is below 43°F (6°C). Disconnect AS hose from EACV and listen for bubbling sound from EACV with engine at idle. No bubbling sound should be heard. See Fig 1.
  2. Warm engine coolant to 64-109°F (18-43°C). Raise engine speed to 1390 RPM. A bubbling sound should be heard from EACV, under this condition.
  3. Warm engine coolant to 131°F (55°C). Increase engine speed to 1390 RPM. An intermittent bubbling sound should be heard from EACV. Allow engine to idle and listen for a bubbling sound from EACV. A bubbling sound should be heard under hot conditions.
  4. With engine coolant above 64°F (18°C), disconnect and plug vacuum hose from vacuum switch, located near EBCV. See Fig 1. A bubbling sound should now be heard from the EACV. Replace components as necessary.
Fig 1: Checking AS System
G95458Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002