EGR Valve Without Back Pressure Transducer
- Check that all vacuum lines are properly routed, all connections are secure, and that vacuum hoses are not cracked, crimped or broken. When the engine is cold there should be no vacuum to operate the valve. If there is vacuum, check PVS function and replace if necessary. There should be no vacuum to the valve at warm curb idle.
- Vacuum should be available at or above part throttle with engine at operating temperature. If vacuum is not available, check PVS function and replace as necessary.
- With engine at idle, apply 8 in. Hg vacuum to EGR valve. The valve stem should move to open the valve and engine idle should roughen. If valve stem moves but idle does not roughen, remove valve and clean inlet and outlet ports with a wire brush.
- With engine at idle, trap 4 in. Hg vacuum in EGR valve and hold. Vacuum should not drop more than 1 in. Hg in 30 seconds.
- If vacuum drops, replace valve. To test valve seat, insert a blocking gasket (no flow holes) between valve and mounting base, then retighten valve. If idle improves, replace valve and remove blocking gasket. If idle does not improve, problem is not in EGR system.