Loud Clunk noise on cold starts

[bmwpower603]

I have been getting loud clunk sound on cold starts. I’ve heard it in other instances, with people having the same issue. I know what it might be, but want to make sure I diagnose it correctly. And want to see what available fixes might be.

The clunk sounds like it’s associated with the throttle flaps. I have run some tests on ista recently. And have code for pressure sensor, on cold starts, along with charge plausibility. ISTA prompted me to run a series of tests on the TAs. And both of them had some things that weren’t OK during the tests.

Is the only wear item the TAs in the intake manifold ports / throttle flap?

I also thought it could be the starter not retracting fast enough..

It could also be part of regular operation if other people can hear a clunk on cold starts. But my clunk is probably more extreme.

Maybe try and have BMW fully diagnose it? Or a reputable Indy shop.

[///M Power-Belgium]

Originally Posted by bmwpower603

I have been getting loud clunk sound on cold starts. I’ve heard it in other instances, with people having the same issue. I know what it might be, but want to make sure I diagnose it correctly. And want to see what available fixes might be.

The clunk sounds like it’s associated with the throttle flaps. I have run some tests on ista recently. And have code for pressure sensor, on cold starts, along with charge plausibility. ISTA prompted me to run a series of tests on the TAs. And both of them had some things that weren’t OK during the tests.

Is the only wear item the TAs in the intake manifold ports / throttle flap?

I also thought it could be the starter not retracting fast enough..

It could also be part of regular operation if other people can hear a clunk on cold starts. But my clunk is probably more extreme.

Maybe try and have BMW fully diagnose it? Or a reputable Indy shop.

=> https://www.m3post.com/forums/showthread.php?t=996069

[wfdeacon88]

Here's my occasional *clanking* at start up.. mine, however, is not necessarily an overnight cold start, as in it can be only 1-4 hours after last driven. It doesn't happen every cold start, which is different than the thread posted above... It has done this for 11 months (I would guess 20-30% of the time), with no ill effects that I have noticed.. I showed the video to my Indy on Friday when getting an oil change... they are going to look into it on the next visit. I've never been able to understand it after reading every single thread on this forum that discusses it. I stopped worrying about it (mostly) since it's intermittent and has not been getting worse.

One thing that seems to make it either not happen or sometimes be lessened is to hit the start button first before starting and let the pumps get power... but this doesn't stop it always, and might just be a fluke.

If someone has any definitive information I'd love to know, otherwise, I will just enjoy the beast and forget about it.

[bmwpower603]

That sound is absolutely the 8 individual throttle flappers opening.

And the same goes with mine, and 90% of the other people that hear it.

It’s normal. But I’m sure in some cases, the throttle actuators could be on there way out. They are supposed to ease into opening and closing. There’s multiple steps that they must go through to open and close.

I did have a code for a pressure sensor / charge plausibility.

So the sound could be related to that in my case.

[romero1990]

mine has that from time to time. also at cold start. certain not TA because both got changed recently. some people mentioned could be starter not retracting.

interesting you say it is the flaps. maybe I was not following your thoughts very well. but the sound is awfully like metal gear grinding.

but I could be wrong. it's a mystery to me for now.

[wfdeacon88]

Originally Posted by bmwpower603

That sound is absolutely the 8 individual throttle flappers opening.

And the same goes with mine, and 90% of the other people that hear it.

It’s normal. But I’m sure in some cases, the throttle actuators could be on there way out. They are supposed to ease into opening and closing. There’s multiple steps that they must go through to open and close.

I did have a code for a pressure sensor / charge plausibility.

So the sound could be related to that in my case.

The one from my video? Just want to confirm... because the noise is quick in my video, hard to type the sound, but.. *CRIIRRRK* in a metallic tone. I know the other S65 noises are there, so confirming this is the noise you were referring to... if so, how is that "certainly" what you said.... I don't think it's typical.

[Scrippy]

Vanos noise maybe?