Have to ask guys, I have the p0171 and p0174 codes after cold air intake and Gibson shorty's that were given to me. Headers didn't have egr hookups so I made a mount and simply plugged it in. Truck was OK around town but I drove here to north FL for the holidays and got like 12mpg hwy now the best I got on these trip in the past was 22mpg like to get some back. Do I need a tune to delete this nasty thing or is there something I can do here on vac. I have new fuel pump new maf and msd wires and new plugs for the most part never done the o2s and the truck starts right up. I might be able to test fuel pump but I think I'm getting ahead of myself but that's every I can think of tight now. Happy new year and thanks in advance!

 

Did you plug the EGR valve opening that used to go to the exhaust? That would let a lot of unmetered air in if it is just open to the atmosphere.

 

Thank you for the reply....I have being testing the o2's with a scan tool all day testing for leaks at mainfold both intake and exhaust. They seem to be fine and in working order. I did reset the code's and then finally unplugged the egr completely and the o2 reads just below 1volt around .800 to .900 with it unplugged and the p0171 and p0174 codes are gone just the egr code stands now I'm happy with that if that's the only code. But a guy here in town said he can tune the truck with hp tuning for 150 but not sure if u want to fool with it. But would I imagine unlock some hp to make the headers and intake worth having and delete the egr. Said that he can advance the timing and fuel trim as well

 

Anything over .5v for the o2s means rich, which explains your bad milage. You need it tuned if you deleted the EGR.

 

Saying that over .5 volts is rich why the codes for lean in bank 1 and 2 then. I mean the Web site I was reading for the scan tool dia. Was saying spray carb clean to get the .800 to 1 volt to make sure they are working. But that was on a cold start getting .800 to .900 and it dose drop to .200 to .500 at times its not staying at .800 to .900 for any long term. But either way it needs turn off to keep the Gibson Headers? Note: egr plugged in is .100 to .800 back and forth and unplugged. 500 to .950. This will cuse rich code? Because lean code gave me horrible mpg

 

That is normal then, the O2 voltage constantly bounces around 0 and 1000mv when operating correctly. Get rid of the EGR crap and have it tuned and the EGR stuff turned off and your mileage will come back.