rallyfiend
Member
2009 STA with 4.6 V8 175K miles, has a very noticeable exhaust leak at cold start. The leak has existed for many months and is getting noticeably louder. It seems to disappear if I let the truck warm up for approximately 20 seconds before driving off. At first I thought I had a manifold leak, but then realized it went away after just a few seconds. I could not find any leaks at flanges or at the manifold/ cylinder head interface. Also no visible signs of exhaust leakage (soot trails or burning). This seems like an engine management issue. My first thought is EGR pipe has a hole in it that has gotten bigger over time. My research seems to indicate that this particular engine does not have an EGR system, so not sure what else it could be.
