Does it behave the same on sunny days?

 

Yep, happened during the summer too.

 

Sounds like intake and/or exhaust CPS.

 

Would that trigger a code though? I didn't get any back from the Peake.

 

Do you think you submerged the O2 sensors when traveling in the downpour?

 

Submerged? Don't think so (was on the freeway the entire time). But very likely could have had water splashed up everywhere

 

Listened carefully again today and i can hear something jumble/shake in the exhaust tone when I go over a bump in that first minute following a cold start. Doesn't sound like an exhaust rattle, but the tone does jumble/shake (again, as best as I can tell, from the midsection of the car around the transmission area) when if I hit a bump.

Hard to listen for it because by the time I hit any other bumps the cars already warmed up and the noise is gone! :confused2

I'm going to have the car up on jacks soon for some brake pads and replacing a control arm, so I'll visually inspect the exhaust when I do that.

 

do you notice the shake and rattle from the midsection on cold starts? I had a noise yesterday that sounded like a louder, blatted VANOS noise from the engine, but it sounded loud right underneath the driver seats and could feel the vibration in the shifter.

The noise sounded kind of baffled and like a RPM based slap. I also thought I could hear it over bumps. But, I also noticed that my exhaust hanger came un-welded from the straight pipes and is causing a rattling noise.

So, I am not sure if these are related or not (maybe cold start is rougher and causes my exhaust to shake violently). My noise goes away after 15 seconds or so, so it was hard to diagnose. Especially, cuz i was freaking out so much when it happened.

 

Wow. Seems like you have a similar issue to me. I just posted today about mine. My issue only happens during rainstorms and the exhaust note is not unusual during cold starts... only while in the heavy rain/puddle.

BUT - one thing you said about the symptoms mirrored mine that I forgot to post about... feeling the vibration in the shifter and being able to hear what seems like a loose exhaust going over bumps while the "noise" is happening.

 

Funny thing is that i did not notice it it (maybe for half a second) this morning when i cold started my car. Maybe because it was under my carport and out of the rain?

Could you describe what yours sounds like more? Mine does not sound like it is necessarily coming from the exhaust. If I had to describe the sound it is almost like a plastic component slapping against metal. When i go over bumps it sounds as if my undertray is slapping, but i know it to be secure.

Check your exhaust to see if it is secure. I am going to try and get a friend over tonight to record my car outside of it on cold start to locate the noise. Could you get a video up?

I honestly cannot tell if mine is coming from the engine and just vibrating through components back to make it sound like it is beneath me.

 

^ Here is a short vid, from inside the car. It is tough to hear

http://s1160.photobucket.com/albums/q489/bdsmitty88/?action=view¤t=VIDEO0074.mp4

 

^ Here is a short vid, from inside the car. It is tough to hear

http://s1160.photobucket.com/albums/q489/bdsmitty88/?action=view¤t=VIDEO0074.mp4

Next time you cold start it and it is "doing it" give the throttle a light/quick rev. Thats when my sound becomes even more pronouced. At idle mine sounds similar to yours. Almost like the valve timing is off and you can "hear" the exhaust scavaging and/or valve overlap.

 

Could it be cats that are bad? Seems like they are located in the area's that you guys are all speaking about...it would explain quite a bit of the noise.

 

Getting warmer and getting interested in fixing this again, how would I be able to test it or what are other symptoms of that? I'm trying to figure out how to diagnose this

 

Also, Does it sound like the first video in this link? I think mine does.

Rod knock - Rod bearing?? - Bimmerforums - The Ultimate BMW Forum

 

Are you really only talking about the first minute? If yes that is perfectly normal. The car is running super rich sort of like have the choke 1/2 on. High idle is normal, the vanos is in a position to make the exhaust burbal just like a bad cps. Just like any other engine, settings are totally different to get a cold engine to start smooth and run. Chasing ghosts.

 

Thats what I was thinking when I read it but was surprised no one else suggested its normal.

I don't think mine cold start different during rain storms but when it cold starts, the exhaust is always louder and the car always idles higher.

 

If its only when its cold and its not what you are used to, it could be the secondary air system is completely stopped now. Doesn't the secondary air smooth out the idle a bit? All cars have their initial cold start deep burble and high idle which is normal, I'm just pointing out that its not normal for you so it must be something. What about the secondary air hoses? If those came undone, wouldn't that cause a change in the exhaust note?

 

If its only when its cold and its not what you are used to, it could be the secondary air system is completely stopped now. Doesn't the secondary air smooth out the idle a bit? All cars have their initial cold start deep burble and high idle which is normal, I'm just pointing out that its not normal for you so it must be something. What about the secondary air hoses? If those came undone, wouldn't that cause a change in the exhaust note?

No.

If the hose was disconnected there would likely be misfire DTCs and surely a related Secondary Air Threshold DTC.