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Discussion Starter #1
Ok so it's been a full day of this, but the exhaust is making that low rumble (almost farty) noise at low RPMs. It seems to disappear on/about 2500 RPMs. The sound is similar (if not exactly) to what it sounds like with failing CPSs. Just so we can eliminate those, I just had all 4 replaced about a month ago. Is this something that O2s can cause?

PS - Almost forgot, no SES lights.

Thanks
 

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Try searching 'blatty' exhaust noise in the M5board search bar. Could be one of several issues.

(Were the 4 CPS you replaced BMW OE or aftermarket? If aftermarket I would start my diagnosis there.)
 

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Discussion Starter #3
No, the 4 sensors were OE.

I'll keep searching..
 

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The CPS's cause the blatty noise because they mess up the VANOS operation and open the exhaust valves too soon. Kinda like when a Jakes brake pops open the exhaust valves on the compression stroke, I suppose. So VANOS going bad can also cause this noise although it seems less common. Can you read codes? Or do the DIS VANOS test?

The other possibility of course is a simple exhaust leak. They tend to show up most when the engine is loaded at low rpm
 

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Discussion Starter #5
The CPS's cause the blatty noise because they mess up the VANOS operation and open the exhaust valves too soon. Kinda like when a Jakes brake pops open the exhaust valves on the compression stroke, I suppose. So VANOS going bad can also cause this noise although it seems less common. Can you read codes? Or do the DIS VANOS test?

The other possibility of course is a simple exhaust leak. They tend to show up most when the engine is loaded at low rpm
Yes, I have a code reader at home which I'll do when I'm back from work.

So a couple things and a question or two.

First, it's now throwing an SES light which isn't that surprising.
Secondly, and I don't know if this is related, but my audio is cutting out. It is only doing it briefly, the cabin just goes silent long enough that everyone can hear my singing voice (which I think is what it sounds like when doves cry). It almost feels like a power failure, it kinda fades in and out, but there doesn't seem to be any other power issues (no dimming lights, etc).

So not to get too far ahead of myself, but is it possible that a CPS can be installed incorrectly? From what I could tell on the DIYs/videos, it looked like there's really only one way for them (at least the exhaust sensors) to go in. I only ask because I had to have them done (Shrek hands) and would like to be able to eliminate it being either a labor or a part issue.

I'll have to look into the VANOS test. The car had VANOS work done on it before I bought it, so this would be my first VANOS problem in my 7 years of E39 ownership.

Thanks
 

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Yes, I have a code reader at home which I'll do when I'm back from work.

So a couple things and a question or two.

First, it's now throwing an SES light which isn't that surprising.
Secondly, and I don't know if this is related, but my audio is cutting out. It is only doing it briefly, the cabin just goes silent long enough that everyone can hear my singing voice (which I think is what it sounds like when doves cry). It almost feels like a power failure, it kinda fades in and out, but there doesn't seem to be any other power issues (no dimming lights, etc).
I can't help you with your audio problem but it does sound a bit unusual. I suggest a new post as there are some people on here who really know that stuff.

So not to get too far ahead of myself, but is it possible that a CPS can be installed incorrectly? From what I could tell on the DIYs/videos, it looked like there's really only one way for them (at least the exhaust sensors) to go in. I only ask because I had to have them done (Shrek hands) and would like to be able to eliminate it being either a labor or a part issue.

The DME monitors for electrical/wiring problems and is also looking for a good signal, which it compares to the crankshaft position sensor signal. So if there was an installation problem, you would get a code.
 

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Discussion Starter #7
So it showed up as "Exhaust camshaft 2 VANOS position control". So what is more likely, a bad install or a bad sensor? These are all only months old....
 

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So it showed up as "Exhaust camshaft 2 VANOS position control". So what is more likely, a bad install or a bad sensor? These are all only months old....
That code means the bank 2 exhaust cam isn't going to where the DME is telling it to go. Could be a bad sensor but it's more likely to be the usual high mileage VANOS problems of plugged solenoid valves and leaking o-rings. Have you ever done any VANOS maintenance?
 

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Discussion Starter #9
That code means the bank 2 exhaust cam isn't going to where the DME is telling it to go. Could be a bad sensor but it's more likely to be the usual high mileage VANOS problems of plugged solenoid valves and leaking o-rings. Have you ever done any VANOS maintenance?
I personally have not. From what I was able to get from BMW that the PO had done RE: VANOS says this: Note intermittent VANOS codes, and installed O-Ring and Pulse generator, camshaft. This was 4 years and nearly 30k miles ago.
 

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Or maybe a wire loss ...it happened to me ..just double check the sensors wires...and same code as you have.
 

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Discussion Starter #11
Or maybe a wire loss ...it happened to me ..just double check the sensors wires...and same code as you have.
This is probably a dumb question, but how do I/how easy are those wires to get to? If they're tucked back there, I may be SOL. My hands are too big to get into a lot of spots in that engine bay...
 

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He is talking about the vanos solenoid wires. They're accessible once you take off the cap plates.
 
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