How can you tell if an EGR valve is good? How can I check it if it's still installed or if it's removed from the vehicle?

Don C.
98 F-150
4.6 V8

 

Use a manual (Haynes or Chilton - 20 bucks) to locate your EGR valve. Loan a vacuum pump/gauge (http://www.autozone.com/Repair/InsideOurStores/tools/diagnostic/body_diagnostic.html) from Autozone and check the EGR valve operation (opening and closure) at the different vacuums according to the manual.