With Back Pressure Transducer

Signal Response Tests

1. Check all system vacuum lines for proper routing and secure connections.
2. Inspect vacuum lines for wear or damage and replace as necessary.
3. Ensure air flows freely with vacuum applied and valve at rest. If valve hold vacuum, clean or replace as necessary.
4. Ensure there is no vacuum to valve at idle . Recheck hose routing if vacuum is present.
5. Make sure there is vacuum to valve with engine at operating temperature at the following speeds:4-140 engine, 3000 RPM; all other engines, kickdown RPM. If there is no vacuum trace system vacuum lines back from EGR valve and replace components as necessary.

NOTE:Refer to vehicle emission decal for kickdown RPM specification.

Diaphragm Test

1. Cycle valve through full travel, using finger pressure on diaphragm. If valve sticks, clean or replace as necessary.
2. Clamp a socket wrench, with an outside diameter approximately 1/16 inch less than inside diameter of tailpipe, into tailpipe.

NOTE:Socket drive hole must be covered and socket installed with open end facing out to achieve proper back pressure.

CAUTION:Do not completely block tailpipe and do not run engine faster than idle or for prolonged periods of time. Also, be sure to remove socket from tailpipe when test is completed.

3. Idle engine and gradually apply vacuum to valve. Ensure valve stem/diaphragm moves and engine idle roughens.
4. Trap 6 inches Hg vacuum in valve and hold. Vacuum must drop more than 1 inch Hg in 30 seconds.
5. If vacuum test is satisfactory but engine idle does not roughen, clean air passages.
6. If conditions in steps 3 and 4 are not met, replace valve.