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Home >> Honda >> 1994 >> Prelude VTEC >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION (EGR) System >> EGR Valve
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EGR Valve

Ensure all connectors between EGR valve lift sensor and ECM are securely connected. Warm engine to full operating temperature. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. Apply vacuum. EGR valve should hold vacuum and engine should die once vacuum is applied. If results are not as specified, replace EGR valve.

  1. Start and idle engine. Disconnect hose No. 16 from EGR valve, located at top of engine. Connect vacuum pump/gauge to hose. If vacuum exists, go to next step. If vacuum does not exist, go to step 4).
  2. Unplug 2-pin connector from EGR control solenoid valve, located over left front fenderwell. Check for vacuum on hose No. 16. If vacuum does not exist, go to next step. If vacuum exists, check EGR system vacuum hose routing. If hoses are okay, replace EGR control solenoid valve.
  3. Turn ignition off. Unplug connector "A" from ECM. Check for continuity between ground and Red wire at 2-pin connector. If continuity exists, repair short in appropriate wire. If continuity does not exist, replace ECM and retest system.
  4. Connect vacuum pump/gauge to EGR valve. With engine idling, apply 8 in. Hg vacuum to EGR valve. If engine stalls or runs roughly, and EGR valve holds vacuum, go to next step. If engine operation remains same or EGR valve does not hold vacuum, replace EGR valve.
  5. Turn ignition off. Unplug 2-pin connector from EGR control solenoid valve, located over left front fenderwell. Turn ignition on. Measure voltage between harness connector Black/Yellow wire and ground. If battery voltage exists, go to next step. If battery voltage does not exist, repair Black/Yellow wire between harness connector and fuse panel.
  6. Connect vacuum pump/gauge to hose disconnected in step 1). Connect fused jumper wire between positive battery terminal and Red wire on EGR solenoid valve connector. Observe voltmeter while connecting jumper wire between Black/Yellow wire on EGR solenoid valve connector and negative battery terminal.
  7. Gauge should indicate about 8 in. Hg within one second. If gauge indicates as specified, go to next step. If gauge does not indicate as specified, go to step 13).
  8. Turn ignition off. Reconnect vehicle harness. Unplug 3-pin connector from EGR valve lift sensor, located on EGR valve. Turn ignition on. Measure voltage between Red/White and Green/White wires on harness connector. If voltage is about 5 volts, go to step 9). If voltage is not about 5 volts, go to step 15).
  9. Turn ignition off. Reconnect wiring to valve lift sensor. Connect test harness. See Figure . Turn ignition on. Measure voltage between terminals D12 and D22 with no vacuum applied to EGR valve. Apply 8 in. Hg vacuum to EGR valve. Voltage should be about 1.2 volts with no vacuum applied and 4.3 volts with vacuum applied. If voltage is not as specified, go to next step. If voltage is as specified, go to step 11).
  10. Check for open or short circuit in White/Black wire between EGR valve and ECM terminal D12. See Figure . If wire is okay, replace EGR valve.
  11. Observe voltmeter as vacuum is applied and released. If voltage increases and decreases smoothly, go to next step. If voltage does not change smoothly, replace EGR valve.
  12. Reconnect hose to EGR valve. Start and idle engine. Connect jumper wire between terminals A11 and A26. If engine stalls or runs roughly, replace ECM and retest system. If engine does not stall or run rough, repair open in Red wire between ECM terminal A11 and EGR control solenoid valve.
  13. Turn ignition off. Inspect hoses No. 16 and 24 for leaks, restrictions and misrouting. If hoses are okay, go to next step. Make any repairs as necessary.
  14. Disconnect lower hose from EGR control solenoid. Connect vacuum pump/gauge to hose. Start and idle engine. If 6-10 in. Hg vacuum exists, replace EGR solenoid valve. If vacuum is not 6-10 in. Hg, replace EGR valve.
  15. Measure voltage at Red/White wire. If voltage is not about 5 volts, go to next step. If voltage is about 5 volts, repair open in wire between EGR valve and ECM terminal D22.
  16. Turn ignition off. Connect test harness connector "D" to ECM only, not to vehicle harness. Turn ignition on. Measure voltage between terminals D20 and D22. If voltage is about 5 volts, repair open in Red/White wire between EGR lift sensor and ECM terminal D20. If voltage is not about 5 volts, replace ECM and retest system.
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