Received an error code for the EGR Valve on my '93 5.8l 4x4. I've been getting only 12-13mpg lately and was trying to figure out if the O2 sensors were bad or what. Does the EGR valve have anything to do with poor mileage, or anything to do with engine performance other than emissions control? Could an EGR error message be the result of bad O2 sensors?
Thanks
BuckarooJim

 

If the EGR valve is stuck open, the engine should idle poorly. If the EGR valve is stuck closed, you may get pinging on acceleration and hard pulls and will fail the NOX test at the emissions station. Let your truck idle, then pull off the vacuum line to the EGR and connect a vacuum pump or source vacuum from the motor or use a syringe with a short piece of hose to the EGR valve, the engine should stumble or die when you pull the vacuum and cause the EGR valve to open. If the EGR seems working OK, check the EGR position sensor (DPFE sensor), or for plugged lines/ports, or adequate vacuum supply (hose leaks, EVR solenoid). A Haynes manual will have a system diagram.

 

What code did you get.