Lately, my 2003 n/a 3.8 grand prix has been only getting 14mpg, small oil leak at LIM, and a P0420 code. I am not worried about the P0420 code now because we have tried 2 new generic cats and the 02 sensors are new. My brother who worked at an Arnolds Motor supply in IA said to check the PCV valve. I pulled it out and sure enough, not a "free or easy" rattle. I did the Homer Simpson "DOUGH" , put it back in and went to NAPA to get a new one. I have 113,000 on the car and got close to 32mpg last summer at 65 ish and mid 20's day to day. We have had some pretty cold days in MN when the highs were below 0*F.
My question is how much can a plugged PCV valve affect?
Thanks in advance to all replies!
