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.
1990 Ford Bronco II RWD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE
EGR Valve (Ported)
- Ensure all vacuum hoses are correctly routed and connected. Replace any crimped or broken hoses. Ensure there is no vacuum to EGR valve at idle. Install tachometer. Disconnect idle air by-pass valve electrical connector. Remove and plug vacuum hose from EGR valve.
- Start engine and idle in Neutral. Note idle speed. Using hand-held vacuum pump, slowly apply 5-10 in. Hg of vacuum to EGR valve. When vacuum is fully applied to EGR valve:
- If idle speed drops more than 100 RPM or if engine stalls, perform step 3. If idle speed does not drop, check for plugged EGR passages or replace EGR valve.
- If EGR passages are blocked, clean EGR passages.
- Remove vacuum from EGR valve. If idle speed does not return to normal, check for contamination, clean valve.
- Ensure no contamination or debris is left in valve or pick-up tube. Replace valve if necessary.
- Unplug reconnect EGR vacuum hose. Reconnect idle air by-pass electrical connector.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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