About 4 weeks ago the check engine light in my '01 Monte SS (3800)
came on and Autozone told me it was an EGR valve error. I purchased a
new one from them and installed it. The light turned off, hasn't come
on since then, but I've noticed anywhere from a 3-5 mpg drop off in my
average fuel consumption since I installed the new EGR valve. Any
thoughts? Is it possible that I bought a poor quality replacement
part from Autozone (I've heard poor reviews of their parts before)?
Would it be reasonable to believe that part is the reason why my mpg
has dropped 17%?
The car has about 98,500 miles on it and I have yet to replace the
spark plugs (suggested at 100,000). I'm going to throw some Gumout
fuel system cleaner in it on the next fill up, and replace the air
filter this evening (hasn't been done for awhile). I replaced the
fuel filter around 65,000 miles.
Any ideas would be appreciated.