[e90lorkp]

Hi all, this whirr happens at idle. Seems to come from OFH/intake manifold area. It goes away if you bring the RPMs up a bit. Recently, prior owner had the valve cover / gasket and OFHG done.

Thanks

[fastboatster]

Had the same noise happen after I replaced my oil pan gasket/rod bearings and disconnected the battery and then fried my cas when I jumped it to prime the oil system. It looks like valvetronic start stop position adaptations can get erased if the battery is disconnected:
https://static.nhtsa.gov/odi/tsbs/20...63029-9999.pdf
I tried the steps in the nhtsa link above without much hope and really thought that this might just be my front or rear main seals, but disconnecting evap solenoid connector for 15 mins and letting the engine to idle did help. In addition, before disconnecting the evap connector, I tried valvetronic reset procedure described for the n52 engine - I.e., with the car in accessory position (ignition on but not running), pressed the gas pedal full stop for 10 times in 15 secs. Didn’t really see too much improvement right away after that, but after a short test drive as the procedure suggested, the sound is gone, at least for now.

[e90lorkp]

Thanks for your reply, fastboatster. What about the noise made you think it was Valvetronic related?

[fastboatster]

Originally Posted by e90lorkp

Thanks for your reply, fastboatster. What about the noise made you think it was Valvetronic related?

I just saw one post in the “understanding the n55’s pcv valve of death” thread in the DIY section. Somebody mentioned that when there’s a valvetronic fault, the engine will start to run using the throttle valve which will cause vacuum to appear in the intake manifold. In my understanding, normally there should be little to no vacuum in the manifold since at idle, the intake valve lift is very small. My guess is that if the valvetronic adaptation is off, then the pressure in the manifold at idle will also be somewhat off - and I also had an error 28a0 in Dme as in the nhtsa document I posted. If there’s now some unexpected vacuum in the intake manifold which is connected to the crankcase ventilation system, then we might start seeing (or hearing) some air getting pulled from the engine seals.
Take my explanation with a grain of salt, even if this is happening due to bad valvetronic adaptations, it might work in a different way. Or there might be some other reason which can cause this such as bad main seals (some bmw sib even says that some seals had a manufacturing defect). However, this seemed to work for me, at least for now, and I didn’t notice any vacuum being pulled from the pcv valve nipple indicating bad pcv, and that whirring noise did not stop when I loosened and/or removed the oil fill cap so probably wasn’t the main seals either, so Valvetronic probably was the only logical reason

[e90lorkp]

I ask because I think you may have got it right on. I bought the car recently knowing that there was a problem with the Valvetronic. The valve cover was just replaced and the mechanic noted that one of the teeth on the eccentric shaft was damaged.

However, right after I bought it, I ran the Valvetronic learn stops procedure, and by sound it seemed to rotate the shaft fine. It's been 300 miles now and it hasn't thrown the code. At the moment, I don't have any telltale symptoms of a failing system, like a grinding noise from the shaft when unlocking the car. When I try and remove the cap while the car is running there doesn't seem to be excessive vacuum.

Do you know if the position sensor is calibrated via where it thinks the stops are, or does it read the shaft position independently? Because if it bases its reading off the stops, and let's say the damaged eccentric shaft stalled the motor and the car incorrectly marked that as one of the stops, then the Valvetronic could be running at the incorrect positions even though it's not throwing codes.

[fastboatster]

I’m not sure how the eccentric shaft position sensor is calibrated, that damaged tooth might or might not throw the calibration procedure off. In any event, try to do the valvetronic adaptation and see if that gets rid of that sound. Depending on the damage to that tooth, it might or might not require the eccentric shaft replacement. Kind of wish that n55 used the same system as the n51/n52, I have heard now that eccentric shaft teeth wear is not uncommon for the n55. I wonder if I can inspect mine using borescope, don’t really want to pull the valve cover off for this. My car also had the valve cover replaced by the PO, wonder if the eccentric shaft issue is what caused them to sell the car, lol)

[fastboatster]

Well, it started to do it again today, during the cold start or when the engine is warm. I did notice that the oil filler cap was somewhat hard to pull due to vacuum. Makes me think that perhaps it’s a pcv valve, it just gets stuck occasionally. I need to understand if the valve cover I got is OEM or aftermarket.

[e90lorkp]

When I first looked at the car, I scanned it and came up with the Valvetronic code. I asked the owner if he knew anything about it. He said no, and also said no when I asked him about any mechanical issues he knew about.

After the appointment, I got the name of the last shop that worked on the car from the CarFax. I called them up, and the mechanical was nice to email me the invoice. Sure enough, the mechanic told the PO about the Valvetronic issue, and the $3000 it'd take to fix it.The PO put the car on CL 3 days later. The PO paid $5500 for this service, even without doing the eccentric shaft. Maybe he thought the car was becoming a money pit and was keeping sunk-cost fallacy in mind. But doing a $5500 service and then selling it immediately? It's kind of odd. So I bought the car knowing what I was getting into. Maybe there's something else he knows about that I don't lol. But the mechanical didn't point anything else out.

Anyway, I never called the guy out for essentially lying to my face about the issue, but I was vague about how in my research this code could indicate a major service was needed. He never denied it. I talked him down $1500 for it, figuring I could fix it myself for under that.

Yesterday I unplugged the eccentric shaft sensor before driving it, locking it into for valve lift. I still heard the sound, thought it was fainter. I think I can live with the sound for now, as long as it's not harming the engine.

Sorry to hear the issue started again. How are your fuel trims?

[fastboatster]

Need to check my fuel trims, my inpa unfortunately only has a German ipo file for the dme (med176kw), so I can’t really find the fuel trims. Perhaps the mhd app can help to read them.
It’s good that the shop was cooperative, I also tried to call the last shop which was on my car’s carfax, but these a-hole “mommylovers” refused to provide any records unless I show up with the car in person, which is a hassle since they are 40 miles and one toll bridge away and only open during the usual working hrs.
As for the valvetronic issue, it’s seems that it’s not that bad to repair except for the cost of the eccentric shaft (~1000), depending on the car’s mileage and how much was paid for it, it might make sense. Eventually, this whistling noise will cause the main seals to leak, which may or may not be a hassle depending on the available tools and equipment.

[fastboatster]

Looks like the lower charge pipe is loose on the intercooler fitting (driver side), will need to tighten its clamp.

[fastboatster]

Originally Posted by fastboatster

Looks like the lower charge pipe is loose on the intercooler fitting (driver side), will need to tighten its clamp.

Looks like the source of the sound is an intake duct, the areas where intake duct pieces are clamped together with oval shaped hose clamps. Need to retighten or replace some rubber gasket pieces. Given that I saw a lot of dust on the throttle body throttle plate and because I removed those to disconnect the injectors and check the spark plugs after doing the rod bearings, an intake leak somewhere between the air filter and the turbo makes sense.

[e90lorkp]

Originally Posted by fastboatster

Looks like the source of the sound is an intake duct, the areas where intake duct pieces are clamped together with oval shaped hose clamps. Need to retighten or replace some rubber gasket pieces. Given that I saw a lot of dust on the throttle body throttle plate and because I removed those to disconnect the injectors and check the spark plugs after doing the rod bearings, an intake leak somewhere between the air filter and the turbo makes sense.

Glad to hear you're figuring it out. I just did the HPFP pump to take care of a long start issue and noticed that the charge pipe that connects to the throttle body is cracked. I ordered a VRSF charge pipe to replace it. I'm fairly certain I have a boost leak because the STFT goes way negative under boost. Hopefully the charge pipe is all it is.

Maybe the leaking charge pipe is causing the whirr? It seems like the sound is coming from the top of the engine, but who knows, with the way sounds reflect around the engine bay.

[fastboatster]

My charge pipe doesn’t seem to be cracked, however lower charge pipe seal where it connects to the intercooler is very flattened and probably doesn’t seal anymore - some oil/blowby liquid was dripping out of that connection when I decided to remove both my charge pipes. The sound at idle was definitely not coming from there, and definitely coming from the intake pipe. Lower charge pipe seems to be making a “whooshy” sound when in boost, however, and my stft is also -11% when getting into the boost. Hope to be able to replace that seal in the next couple of days