I posted about this a while ago, but never got any feedback, so I figured I'd try again one more time before dealing with taking it into the shop.
Every time I start driving a cold engine, after about 5-10 minutes I get this loud whistling noise at idle throttle. It's always throttle position dependent, not speed or RPM. Then after another 10 minutes or so, it goes away completely.
I originally thought some kind of vacuum leak, but traced all vacuum lines, not finding any cracks, and even replaced a few worn vacuum boots. I also have a P1494 code that won't go away (leak detect pump pressure switch), which is what made me think vacuum leak (but it might just be the pump itself if it's not related). But the fact that it doesn't happen with a cold or completely warmed engine makes me think leak from the block or a gasket somewhere.
A few weeks prior to this starting, I did have the exhaust manifold replaced in the shop, which obviously means removing the intake manifold, etc, so maybe something involved with that is causing the issue?
Camera is pointed at where it sounds like it's coming from, rear of the block, but I just can't pinpoint it, even with a mechanics stethoscope. Any ideas welcome, thanks.
EDIT: Can't get the video playing right in the post itself, link is below
VIDEO LINK
Every time I start driving a cold engine, after about 5-10 minutes I get this loud whistling noise at idle throttle. It's always throttle position dependent, not speed or RPM. Then after another 10 minutes or so, it goes away completely.
I originally thought some kind of vacuum leak, but traced all vacuum lines, not finding any cracks, and even replaced a few worn vacuum boots. I also have a P1494 code that won't go away (leak detect pump pressure switch), which is what made me think vacuum leak (but it might just be the pump itself if it's not related). But the fact that it doesn't happen with a cold or completely warmed engine makes me think leak from the block or a gasket somewhere.
A few weeks prior to this starting, I did have the exhaust manifold replaced in the shop, which obviously means removing the intake manifold, etc, so maybe something involved with that is causing the issue?
Camera is pointed at where it sounds like it's coming from, rear of the block, but I just can't pinpoint it, even with a mechanics stethoscope. Any ideas welcome, thanks.
EDIT: Can't get the video playing right in the post itself, link is below
VIDEO LINK