[rtl32]

Context:

2014 M235i 6MT with extensive mods listed in my sig.

83k miles. Always do aggressive maintenance.

Issue:

After a recent drive from Canada to NJ I began noticing a strange sound right before getting home. Like an electric leafblower or WW1 fighter plane...

Every time the revs are in the mid-higher range and fall back down (freely or when engine braking) I hear a nasty almost machine like whirring/winding noise that seems to come from somewhere in front of me.

AC/heat on/off, clutch in/out, gear selected (or lack of in neutral), and road speed do not make a difference. It's completely RPM dependent and reproducible both freely revving, or with more intensity and volume when engine braking. It seems that over 4k the noise is less aggressive and around 4k it resonates more until around 3k. I can hear it best with windows up/sunroof shade closed, can't hear anything extra when windows are opened or when the hood is opened and I've revving from the drivers seat. No CEL in 16k+ miles since the last one which was intake related.

What could it be:

Dorch HPFP crapping out? (Fuel pressure is perfect as high as E50 in as low as 30 degree weather)
Pulleys/belt issues? (belts look great, tensioner seems tight, no squeals or chirps or charge system malfunctions)
Flywheel? (clutch holds perfectly with no shutter or slippage)

Next step:

Get someone else to rev the car with the hood open so I can listen closer.

Anybody have this before? Suggestions for where to look?

Sound is clear as day in both videos. Focus on the moment the revs peak and start falling after each throttle application and the electric leafblower/WW1 Plane noise that follows.

[aerobod]

I’d look at the bearings in the accessory belt idler and tensioner pulleys first: https://www.realoem.com/bmw/enUS/sho...diagId=11_4454

[rtl32]

Originally Posted by aerobod

I’d look at the bearings in the accessory belt idler and tensioner pulleys first: https://www.realoem.com/bmw/enUS/sho...diagId=11_4454

The tensioner pulley has a little bit of a pulsation to it when it's idling. When revved it smooths out and the system seems to be under more tension. Belt is in great condition with no cracks or wear.

Pulled the belt off. The alternator pulley seems pretty tight, the inner aspect seems to be able to rotate separately from the belt surface of the pulley, with a decent amount of resistance between the two. the AC compressor outer has the slightest amount of play in it and the inner wheel definitely isn't rock solid smooth like a bearing should be. The roller pulley is rock solid smooth with no play at all.

BUT the noise was still present when revved with the belt off the car.... So these may need some attention but I don't think they are making the noise.. The HPFP seems noisier than it has ever been, confirmed with the fist around a socket extension stethoscope method.

[rtl32]

So at this point it's not something off the accessory belt on the front of the engine.. And it's not trans/driveline/diff noise because it happens stationary. So it's got to be somewhere between the harmonic balancer and the flywheel..

[jb-slow]

Maybe check the turbo for shaft play?

[rtl32]

Originally Posted by jb-slow

Maybe check the turbo for shaft play?

I'll give it a look. My boost feels perfectly normal though and I have full power



This is the closest video I've found of a similar noise and they are saying it is the timing chain/ oil pump related.


Post #12

https://f30.bimmerpost.com/forums/sh....php?t=1310467

[rtl32]

Update:

Drove to vermont and parked my car. After a long day of skiing came out to have the car start super rough after a very long crank, sputter and run on a few cylinders for a little, and die out completely once the fuel in the line was used. Now I'm not getting any fuel and the car cranks forever but won't start. Only codes are misfire codes across the board from running out of fuel while cold. There is a gnarly rattle/ring from the HPFP area when cranked (no it's not a rod knock or block sound).

So I'm thinking fuel is getting blocked by the HPFP due to the dead no start condition combined with the recent uprise of the noise from its area.

Logging shows no HPFP pressure, here's 4 startup attempts

https://www.bootmod3.net/log?id=63cd...90c6b520ed018a

Suspecting this noise was being caused by the recently apparent fuel system failure, I contacted Dorch Engineering, and I've been 2nd day air'd a new Stage 1 pump for $300.

Here is their reply to my email and log:

"For these symptoms to occur here’s the ONLY possible causes in the order of most likely to least likely:

Incorrect software - This would only be possible if you flashed a new tune in the parking lot without having the “Dorch HPFP” option selected in the config menu before flashing or if the flash was corrupted (corruption could be the case if you aren’t getting faults for this issue). A full reflash would be recommended to ensure this is not the case. Instructions on a full BM3 reflash can be given if needed.

Disconnected HPFP electrical connector – Definitely worth checking since it was spliced instead of using the correct harness adapter.

Faulty LPFP or EKP

Completely Seized HPFP - This is extremely rare and can only be caused by install errors such as a loose pump from improper torque and/or lack of threadlock."

I'm not only impressed with the speed and amicability of Dorch's customer service over email, I'm also very impressed with their willingness to help me out with the 80% discount + 2 days shipping on a part I bought from a private sale, new in box without any receipt or anything to my name. They clearly have their products back, not just their sales. They recognized my situation and have made every effort they can to help diagnose and provide me with the parts needed, in time to travel back up, even though their product failing is their least likely diagnosis. Any other company would have told me to prove it wasn't the EKP or LPFP first.. Dorch said let's prepare you for everything instead.

I am returning to Vermont on Saturday to fix my car in the frigid parking lot because getting a tow 250+ miles home is almost 2 grand and I'd rather spend that on ski tickets and mountain beer. I also have a LPFP and EKP module being shipped to me (Bosch OE and totaled-take off so not too bad) so that I'll have everything that could have failed.

I have AAA Premier as well that will activate on Monday in case I'm unable to fix it, but I'd rather drive it home after sucking it up and having a frigid warm cider and repair session with the boys than pay 600+ for the tow even after AAA and still have to fix the car. My garage is cold in NJ too.

Anybody ever seen a HPFP completely fail?

[XutvJet]

If it were me, I'd pull the oil filter and check for metal in the filter and residual oil in the filter housing. The engine may had been hard to start because the cold oil was like molasses and perhaps if its an oil pump issue and it failed, it possibly then locked up the motor. This doesn't sound good to me at all. I have a hard time believing this is a HPFP issue. Never heard of a HPFP whining. Oil pump whine as rpms drop as it dies? Yep. The N55 oil pump is write in the vicinity of the HPFP as well.

[rtl32]

Originally Posted by XutvJet

If it were me, I'd pull the oil filter and check for metal in the filter and residual oil in the filter housing. The engine may had been hard to start because the cold oil was like molasses and perhaps if its an oil pump issue and it failed, it possibly then locked up the motor. This doesn't sound good to me at all. I have a hard time believing this is a HPFP issue. Never heard of a HPFP whining. Oil pump whine as rpms drop as it dies? Yep.

Thank you for the input but I really don't see that as a possibility. But after this stint I will be pulling the filter to have a look. The engine cranks perfectly, without delay, without making any block related sounds. It's not locked or knocking in any way.

The HPFP works off of an RPM driven cam too.


The lowest the fuel rail pressure the switch can read is 106-7 psi, meaning my log with that reading indicates there is likely even less pressure than that. Even after 2-3 revolutions of the engine fuel rail pressure should be detectable. 10 seconds of cranking @ 165rpm and no indication of measurable rail output, - is a fueling issue.

Your theory may be applicable to the fuel system though, if it did fail like I'm thinking. If the HPFP piston is shot who knows what kind of metal particles it will send to the injectors and into the cylinders once fuel does flow again. So I'm going to disconnect the fuel rail when I get to the car, test the low pressure side for function, fix if needed, if not - then fix the high pressure side if nothing else has been found. Then spray some fuel into a paper towel from the rail to clear out the line with the new HPFP if it comes to that.

Thank you for giving me the inspiration to think of metal particles.

Will update when I get back to the car.

[XutvJet]

What about the vacuum pump? That's in the same area as the HPFP and per this thread, the vacuum pump can make knocking sounds and cause fuel pressure issues. Not an easy fix though.

https://f30.bimmerpost.com/forums/sh....php?t=1987629