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.
EGR Control Valves
Increased EGR flow, required to meet emission standards, adversely affects driveability. To overcome this problem, this EGR system increases EGR flow during high load operations and decreased EGR flow during low load operations. Two EGR valves are used to accomplish this.
The main EGR valve is controlled by carburetor vacuum, which is governed by throttle openings. Vacuum level at idle and wide open throttle is low; therefore, no EGR operation occurs in these modes. A thermo valve also controls vacuum application to this valve.
The sub EGR control valve is mounted so it is directly linked to throttle valve and thus mechanically controlled. See Figure. This valve more closely modulates EGR flow in response to throttle valve position.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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