Home ReviewsRefund
Home/Ford/LTD Crown Victoria/Ford LTD Crown Victoria I (1983-1991)/Repair manual/Testing & Diagnostics/EGR Function Testing
Contents Section: Testing & Diagnostics All sections

EGR Function Testing Ford LTD Crown Victoria I

Testing & Diagnostics ~728 words

BACKPRESSURE VARIABLE TRANSDUCER EGR SYSTEM

  1. Check vacuum lines for correct routing. Disconnect Idle Speed Control (ISC) connector (EFI only). Disconnect and plug vacuum supply hose from EGR valve nipple. Start engine and ensure engine idle speed is within specification.
  2. Using hand-held vacuum pump, slowly apply 5-10 in. Hg to EGR valve. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds.
  3. Reconnect ISC connector and EGR supply hose. Disconnect vacuum connector at backpressure variable transducer. Gently blow into center port of transducer until relief valve closes.
  4. Apply 5-10 in. Hg to bottom port of transducer and hold. Transducer should hold vacuum at bottom port as long as pressure is applied to center port.
  5. Using a "T" fitting, apply 5-10 in. Hg to bottom and top ports of transducer. Transducer should hold vacuum. If system does not respond as indicated, test EGR control system. If testing is required, see appropriate COMPONENT TESTING article in the EMISSION section.

ELECTRONIC EGR VALVE

  1. Connect vacuum gauge to valve. Start engine. Apply 6-10 in. Hg to EGR valve and hold. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds.
  2. Check vacuum lines for correct routing. Disconnect vacuum hose at EGR valve and connect vacuum gauge to hose. Disconnect idle air by-pass valve (1.9L EFI only). Accelerate engine to 2000-2500 RPM and release throttle. Repeat 8-10 times and check for consistent response. NOTE: EGR Vent Solenoid (EVRV) allows a small vacuum signal (less than 2.5 in. Hg) at idle.
  3. If vacuum rises above zero with cold engine, EGR valve diaphragm is leaking and valve should be replaced. With engine warm, vacuum should rise above 15 in. Hg and return to zero when throttle is released.
  4. If system does not respond as indicated, test EGR control system. If testing is required, see appropriate COMPONENT TESTING article in the EMISSION section.

INTEGRAL EGR BACKPRESSURE TRANSDUCER VALVE

  1. Check vacuum hose routing. Disconnect EGR valve hose and connect vacuum gauge to hose. With engine warm, there should be vacuum to transducer at 3000 RPM for 2.3L engines, or kickdown RPM on all other engines. If vacuum does not exist, check vacuum lines from EGR valve to source.
  2. Clamp a plug (freeze plug may be used) into end of tailpipe, about 1/16" less than I.D. Connect hand-held vacuum pump to EGR valve. Idle engine and apply vacuum gradually. EGR valve stem/diaphragm should move smoothly and engine should drop at least 100 RPM.

PORTED EGR VALVE

  1. Check vacuum lines for correct routing. Disconnect vacuum hose at EGR valve and plug hose. Disconnect idle air by-pass valve (EFI only).
  2. Connect vacuum pump to EGR valve. Start engine. Apply 6-10 in. Hg to valve and hold. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds.
  3. Reconnect idle air by-pass valve (EFI only). Reconnect EGR vacuum hose. If system does not respond as indicated, test EGR control system. If testing is required, see appropriate COMPONENT TESTING article in the EMISSION section.

EGR VALVE/BACKPRESSURE TRANSDUCER ASSEMBLY

  1. Check vacuum hose routing. Disconnect EGR valve hose and connect vacuum gauge to hose. With engine warm, there should be vacuum to valve at 2000-3000 RPM. If vacuum does not exist, check vacuum lines from EGR to source.
  2. Clamp a plug (freeze plug may be used) into end of tailpipe, about 1/16" less than I.D. Connect vacuum pump to EGR valve. DO NOT disconnect transducer from EGR valve.
  3. Idle engine and gradually apply 6-10 in. Hg. EGR valve stem/diaphragm should move smoothly and engine should drop at least 100 RPM.

VACUUM AMPLIFIER

  1. Check for adequate manifold vacuum. With engine warm and at curb idle, connect vacuum gauge to port "O" on amplifier which leads to EGR-PVS (EGR Ported Vacuum Switch). Vacuum should not read more than 2 in. Hg at idle.
  2. Disconnect venturi hose at carburetor. Increase engine speed to 3000 RPM on 2.3L engines, or 2000 RPM on all other engines. Vacuum should not change. Maintain high engine speed and reconnect carburetor venturi hose.
  3. Vacuum gauge should register at least 4 in. Hg. Return engine to idle. Vacuum gauge should return to initial reading. If vacuum gauge does not return to initial reading, replace vacuum amplifier.

More articles — Engine Performance