Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1985RV CUTAWAY 5.8 GREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMEGR SYSTEMTESTINGELECTRONIC SONIC EGR VALVE
1985 Ford RV Cutaway 5.8 G
Electronic Sonic EGR Valve
1985 Ford RV Cutaway 5.8 GSECTION Electronic Sonic EGR Valve
- Connect vacuum gauge to valve. Apply 6 in. Hg vacuum to valve and trap. Vacuum should not drop more than 1 in. Hg in 30 seconds. If so, replace valve "O" ring or EVP sensor.
- As sonic valve is part of EEC system, check all circuitry as described in EEC article. See COMPUTERIZED ENGINE CONTROL section. Mechanical function can be checked as follows: Check vacuum lines for correct routing.
- Disconnect vacuum hose at valve and connect vacuum gauge to hose. Accelerate engine to 2000-2500 RPM and release throttle. Repeat 8-10 times and check for consistent response.
- If vacuum rises above zero, when engine is cold, diaphragm is leaking and valve should be replaced. With engine warm, vacuum should not rise above 15 in. Hg and should return to zero when throttle is released.
- If vacuum does not go to 15 in. Hg, check vacuum source and service. If vacuum does not return to zero or is inconsistent, solenoid is worn and should be replaced.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.