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Home >> Acura >> 1998 >> Integra GS-R, 4D Sedan >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Air Induction Systems >> Intake Air By-Pass (IAB) System >> IAB System Inspection (2.5TL)
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IAB System Inspection (2.5TL)

  1. IAB control solenoid valve is located on top of intake manifold. Before testing system, ensure IAB control valve shaft is not binding or sticking. Ensure IAB control valve moves smoothly. With engine at idle and IAB control valve vacuum hose disconnected, ensure IAB control valve arm is in contact with upper stop.
  2. Reconnect vacuum hose. See Fig 1. Ensure IAB control valve arm is in contact with lower stop. If a problem exist, clean linkage and shafts with carburetor cleaner. DO NOT  adjust upper or lower stop. If problem still exists, disassembly intake manifold and check IAB valve body assembly.
  3. Start engine and allow to idle. Disconnect IAB control diaphragm vacuum hose. Check for vacuum at hose. See Fig 1. If vacuum exists, go to step 8). If vacuum does not exist, go to next step.
  4. Remove vacuum hose from IAB vacuum tank. If vacuum exists at vacuum tank, go to next step. If vacuum does not exist at vacuum tank, repair blockage or vacuum leak between intake manifold and vacuum tank.
  5. Turn ignition off. Disconnect IAB control solenoid valve 2-pin connector. Turn ignition on. Measure voltage between solenoid valve connector terminals. If battery voltage is not present, go to next step. If battery voltage is present, replace IAB control solenoid valve.
  6. Ensure ignition is on. Measure voltage between ground and solenoid valve harness connector terminal No. 2 (Black/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair open in Black/Yellow wire between IAB control solenoid valve and ECM fuse No. 4 (20-amp), located in underdash fuse box.
  7. Backprobing, connect a fused jumper wire between PCM 26-pin connector terminals No. 9 (Pink/Blue wire) and No. 26 (Brown/Black wire). See Figure. If solenoid valve does not click when jumper wire is connected, repair open in Pink/Blue wire between IAB control solenoid valve and PCM. See WIRING DIAGRAMS article. If solenoid clicks when jumper wire is connected, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM.
  8. Increase engine speed to more than 5000 RPM. Check for vacuum at IAB control diaphragm hose. If vacuum does not exist, system is okay. If vacuum exists, go to next step.
  9. Disconnect IAB control solenoid valve 2-pin connector. Check for vacuum at IAB control diaphragm hose. If vacuum exists, replace IAB control solenoid valve. If vacuum does not exist, go to next step.
  10. Turn ignition off. Disconnect PCM 26-pin connector. Check for continuity between ground and IAB control solenoid valve harness connector terminal No. 1 (Pink/Blue wire). If continuity exists, repair short in Pink/Blue wire between PCM 26-pin connector terminal No. 9 and IAB control solenoid valve. If continuity does not exist, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM.
    Fig 1: Identifying IAB System Components (2.5TL)
    G98E11340Courtesy of AMERICAN HONDA MOTOR CO., INC.
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