This may have been covered before, but I need advise on what to do to fix it or as I've heard wire it open.....
Under heavy throttle, there is a fluttering noise in the induction system.....
I understood that when heavy throttle is applied that the valve fully opens to allow for more air, and if with age or whatever the valve can cause flutter noise....
So my question is,
What can i do, and where are these valves.....I looked all over and can't tell exactly......are they after air cleanner mounted on the front of the intake manifolds....? where....????

Any advise would be greatly appreciated....

Regards
wess

Nobody.....? experience this problem.....in a 97 850CI....?

I think you might be talking about the DK motors. If that is the case, they might just need a thorough cleaning.

I think you might be talking about the DK motors. If that is the case, they might just need a thorough cleaning.
Thanks for the reply.....
But I'm not sure what DK motors are.....
Can you explain to me, I'm a newbie with this car....
But it's definitely an induction noise......3/4 throttle.....or more


thanX
wess

Sorry cannot help as I am far more familiar with the M70 E31 and you have an M73. Throttle bodies (DK Motors) changed from Bosch to Siemens on the M73 and they are not prone to failure like the M70 Bosch style are. Contact MWrench in Los Gatos and see what he has to say as he is the foremost expert on the BMW V12's that I know of.

I think I know what you are referring to. I actually have a sort of fluttering noise going on now as well, but it's pretty specific. It's usually just when the engine is cold, and for me it appears under moderate (but not hard) acceleration, around 1800-2200 rpm. After that, it quiets down.

If I figure it out before you, I'll post, and if you solve yours first, please post as well ;)

Sorry cannot help as I am far more familiar with the M70 E31 and you have an M73. Throttle bodies (DK Motors) changed from Bosch to Siemens on the M73 and they are not prone to failure like the M70 Bosch style are. Contact MWrench in Los Gatos and see what he has to say as he is the foremost expert on the BMW V12's that I know of.

Correct there, contact MWrench. I miss-read the description of your car - thought it was a '91. I will be going to the eye doctor today....

PCV valves??? on the valve covers.........2 on the V12.......

Pumped makes a good point. PCV Valve. It's plastic and after a decade...

my 92 850i does that too. Mostly when it's cold under moderate throttle.

i had what seemed to be intake noise in my 96 850ci...but only when cold.

it seems that the 2 rubber hoses from the airpump were bad, once replaced the odd noise went away..

just sharing,

PCV valves??? on the valve covers.........2 on the V12.......

So from what i'm seeing it may be these valves....that are 10 years old and may be due for replacement....
Any inspection techic that will verify.....I mean...
Once I pull them off will it be obvious....?

Another post says hoses.....?

Just want to be able to look at the possibilities, and only have to do a disassembly once.....

Any words of advise is appreciated....as was the detail above

thanX
wess

The hoses that are talked about are at the very front of the engine right in the middle (2 hoses, one on each side of center) and connect the air pump lines to the one way valves that go to the exhaust manifolds (emmisions related) . they get very spongy and will finally disintegrate. If you touch hoses in the front that feel very spongy, those will be the ones.

Comparable noises observed on a M70 engines will probably not be applicable to your situation, the entire PCV system is different on the M73 engine.

ThanX,
At least I know where to start and what to look for....
mucho appreciated


wess

Try sniffing out possible vacuum leaks with a smoke machine. Since your car is over ten years old, there are plastic/rubber parts that will be worn out. If you replace your PCV valves, you should consider replacing your IM gaskets and Valve Covers as well. You are going to have to replace all of these items sooner than later anyhow. Save $ and time in labor fees. The last thing you'd want is to replace the PVC valves and a week later have your IM sucking in outside air due to a breach in rubber gaskets. You'd be saying hello to double the labor fees :(

Cheers

I checked for air leaks on my 92 850, and found the problem one of the hoses had a crack in it, and I fixed it, and it fixed the noise. Now my 850 sounds great again cold or hot.