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HOMESERVICE MANUALSFORD1988BRONCO 4.9 Y, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMEGR FUNCTION TESTINGEGR VALVE
1988 Ford Bronco 4.9 Y, Automatic

Electronic EGR Valve

1988 Ford Bronco 4.9 Y, AutomaticSECTION EGR Valve
  1. Connect vacuum gauge to EGR 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 (EGRV) allows a small vacuum signal (less than 2.5 in. Hg) at idle.
  3. If vacuum rises above zero with cold engine, diaphragm is leaking and EGR valve should be replaced. With engine warm, vacuum should rise to more than 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.
RENDER: 1.0x

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • The engine overheats, stalls repeatedly, or misfires under load.
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