Bronco L6-300 4.9L VIN Y 1-bbl (1983)
EGR Valve: Testing and Inspection
EGR Valve Tests, 1983-85
PORTED TYPE EGR VALVE
Signal Response Test
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 that there is no vacuum to valve at idle with engine at normal operating temperature. Recheck hose routing if vacuum is present.
4.
Ensure that there is vacuum to valve at 3000 RPM on 4-140 engine, or kickdown RPM on other engines, with engine at operating temperature. If
there is no vacuum, trace system vacuum lines back from EGR valve and replace components as necessary. Refer to vehicle emission decal for
kickdown RPM specification.
Functional Test
1.
Operate engine at idle and apply 8 inches Hg vacuum to valve. Valve stem should move, opening valve, and engine should roughen.
2.
If valve stem moves but engine does not roughen, remove valve and clean inlet and outlet ports with wire brush. Do not use sand blasting or
gasoline to clean EGR valve.
3.
Run engine at idle and trap and hold 4 inches Hg vacuum.
4.
If vacuum drops more than 1 inch Hg vacuum in 30 seconds, replace valve.
Seat Test
This test should be performed when the valve is suspected of leaking, indicated by rough engine operation
1.
Install blocking gasket (no flow holes) between mounting and valve, then retighten valve.
2.
Improved engine operation indicates a defective valve. Clean or replace as necessary.
3.
Replace blocking gasket with conventional gasket.
INTEGRAL BACK PRESSURE TRANSDUCER & VALVE & TRANSDUCER TYPE EGR VALVES
Signal Response Test
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.
Disconnect and plug vacuum line to EGR valve, then connect vacuum pump to valve.
4.
Run engine at idle and apply 6 inches Hg vacuum to valve.
5.
If vacuum holds and valve opens and stays open, replace valve.
6.
Ensure that there is no vacuum to valve at idle. If there is, check hose routing.
7.
Ensure that there is no vacuum to valve or valve operation when engine is cold. If there is, check ported vacuum switch and thermal vacuum
switch, replacing as necessary.
8.
Ensure that there is vacuum to valve at 3000 RPM on 4-140 engine, or kickdown RPM on all other engines, with engine at operating temperature.
If there is no vacuum, trace system vacuum lines back from EGR valve and replace components as necessary. Refer to vehicle emission decal for
kickdown RPM specification.
Functional Test
1.
Select drive socket wrench with O. D. of approximately 1/16 inch less than I. D. of tailpipe.
2.
Cover drive socket hole and insert socket in tailpipe with open end facing out. Do not block tailpipe fully and do not run engine faster than
idle or for prolonged periods of time. Be sure to remove socket from tailpipe at end of test.
3.
Run engine at idle and gradually apply vacuum. Valve stem/diaphragm should move smoothly and engine should roughen.
4.
Trap 6 inches Hg of vacuum and hold. Vacuum should drop more than 1 inch Hg in 30 seconds.
5.
If valve stem/diaphragm moves smoothly but engine does not roughen, clean valve passages.
6.
If conditions in steps 3 and/or 4 are not met, replace valve.
7.
If valve is suspected of sticking, remove valve from engine and cycle valve by pressing carefully with fingers against lower transducer plate.
8.
If valve sticks open when fingers are released, replace valve.
9.
If valve does not stick, clean inlet and outlet ports with wire brush. Do not use sand blasting or gasoline to clean the valve.
