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.
1987 Mazda 626 BaseFACTORY OEM SERVICE PROCEDURE
EGR System: Turbo
- Check all connectors, hoses and routings for cracks, leakage, or restrictions and repair as needed. Bring engine to normal operating temperature and run at idle. Remove and plug vacuum hose at EGR control valve. If engine runs rough, test EGR control valve.
- Remove plug from vacuum hose and connect vacuum gauge. With engine at idle, vacuum should not be present. Increase engine speed to 2500 RPM. Vacuum should be present. If procedure fails, test duty solenoid valve and EGI control unit terminals "2M" and "2N".
- Install vacuum gauge between duty solenoid valve and EGR control valve. Increase engine speed to 2000 RPM and note amount of vacuum. Disconnect and plug vacuum hose at EGR control valve. Increase engine speed to 2000 RPM. Vacuum should be greater than previous reading. If procedure fails, test EGR position sensor, EGR duty solenoid valve and EGI control unit terminal "2F".
- With vacuum hose disconnected at EGR control valve and vacuum gauge connected, disconnect Green/Black wire of water temperature switch. Increase engine speed to 2500 RPM and ensure vacuum is not present. If vacuum is present, test duty solenoid valve and EGI control unit terminal "1H".
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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