I have a 2000 Windstar with the 3.8l engine and 129,000 miles on it. I have been trying to diagnose 0171/0174 codes and have a question about a whoosh I hear when I goos the throttle manually. At first I thought this was caused by a vacuum leak somewhere around the upper intake manifold, but the sound is resonating from the intake manifold cover itself. This is apparent if I put my ear directly on the plastic cover. Please see this video:
http://youtu.be/RD8xEsD5jz0 which clearly illustrates what I am hearing. My question is: Is this sound normal? I've not heard this before but I haven't ever manually goosed the throttle from under the hood like this before. I just want to make sure I'm not chasing a Red Herring.
I have checked the periphery of the cover and there are no leaks. I have triple checked all of the vacuum lines and fittings and cannot find any leaks other than a small one at one of the IMRC bushings, which seems to be normal. The van has had the valve cover/isolator bolt TSB performed previously. I've also cleaned the MAF sensor, checked the EGR valve, and replaced the DPFE sensor.
Thanks!