Does anyone know what causes excessive backflow through the EGR? Check engine light is on and when scanned, thats what it keeps coming up as. The L is running rough now at part throttle. Replaced plugs and it still does it. Any help would be appreciated. I have a 2000.
Thanks,
Jeff

 

Your EGR valve may be carboned-up causing the valve to stay cracked open. Too much EGR flow can cause the engine to run 'rough' or stop. There are several(too many for me to post) things that can be tested for this condition. You might try removing(only when 'stone' cold!) the EGR valve and clean it off with a wire brush and/or screwdriver. Don't use any solvent as you can damage its diaphragm.

Dan

 

You may have a bad DPFE sensor. It is quite common for them to go bad on our trucks. A bad sensor will cause the engine to run rough at part throttle. I have had mine replaced three times.