[kazbek1]

*2007 335i, AT, FBO, 93 Oct, MHD Stage 2+ Map 10, 139k miles*

Hello everyone. I started my car today after it had been sitting for about 4.5 hours. I noticed the typical injector tick but with that was a deeper 'WURRR' sound. It almost sounds like something is vibrating. Popped the hood and didn't see anything but sounded like it was coming from the alternator/accessory pulleys/possibly fuel pump area.

I gave it a little bit of gas to see what was going on and when I tapped it to 1000 RPMs, the car stuttered, dropped in RPM, and felt like it was about to stall for a second. It quickly went back to a normal idle. I did this a couple more times and did the same thing but only when I tapped it gently. If I stepped on it harder, the RPMs would rise/decrease as normal. Wondering if anyone could decipher the log I took of me tapping the gas. I think the shutter/borderline stall was recorded.

Note: no error codes were displayed and haven't touched the engine or played with any MHD settings in months.

VIDEO: https://youtube.com/shorts/e8cc0wFLmno

https://datazap.me/u/kazbek1/log-165...og=0&data=3-21

[Jklad]

Originally Posted by kazbek1

*2007 335i, AT, FBO, 93 Oct, MHD Stage 2+ Map 10, 139k miles*

Hello everyone. I started my car today after it had been sitting for about 4.5 hours. I noticed the typical injector tick but with that was a deeper 'WURRR' sound. It almost sounds like something is vibrating. Popped the hood and didn't see anything but sounded like it was coming from the alternator/accessory pulleys/possibly fuel pump area.

I gave it a little bit of gas to see what was going on and when I tapped it to 1000 RPMs, the car stuttered, dropped in RPM, and felt like it was about to stall for a second. It quickly went back to a normal idle. I did this a couple more times and did the same thing but only when I tapped it gently. If I stepped on it harder, the RPMs would rise/decrease as normal. Wondering if anyone could decipher the log I took of me tapping the gas. I think the shutter/borderline stall was recorded.

Note: no error codes were displayed and haven't touched the engine or played with any MHD settings in months.

VIDEO: https://youtube.com/shorts/e8cc0wFLmno

https://datazap.me/u/kazbek1/log-165...&data=3-21

Mine will exhibit this same behavior with a tap and a dip on occasion but only when it's been running for a while. Manual trans. It'a been a few years and nothing bad has ever happened lol.

[kazbek1]

Originally Posted by Jklad

Mine will exhibit this same behavior with a tap and a dip on occasion but only when it's been running for a while. Manual trans. It'a been a few years and nothing bad has ever happened lol.

Yea I've never noticed it before and seems like it only happens when I hit exactly 1000rpm. 900 or 1100 rpm it goes back down to idle no problem. That and this strange noise is just throwing me off. Thanks for the feedback!

[Jklad]

Originally Posted by kazbek1

Yea I've never noticed it before and seems like it only happens when I hit exactly 1000rpm. 900 or 1100 rpm it goes back down to idle no problem. That and this strange noise is just throwing me off. Thanks for the feedback!

For mine it's not related to rpm, it's more to do with the act of just barely tapping the gas so the Rpms pop up and then they plunge. It's so odd. And inconsistent. Damn n54 issues.

[kazbek1]

Originally Posted by Jklad

For mine it's not related to rpm, it's more to do with the act of just barely tapping the gas so the Rpms pop up and then they plunge. It's so odd. And inconsistent. Damn n54 issues.

Right!? I figured I'd go over regular maintenance items first to try and find the culprit. I check my coils/plugs and noticed some oil pooled in the oil freeze plug reservoir thing between 6 and 5. Pulled #6 spark plug and looked fine but when I pulled #5, I got this:


I guess it's time for me to change the VCG...again. Not sure if that's what's making the noise and causing my car to act strange when I rev it but it's just another thing I need to do. I swear, this car...

[Saif2018]

Originally Posted by kazbek1

Right!? I figured I'd go over regular maintenance items first to try and find the culprit. I check my coils/plugs and noticed some oil pooled in the oil freeze plug reservoir thing between 6 and 5. Pulled #6 spark plug and looked fine but when I pulled #5, I got this:


I guess it's time for me to change the VCG...again. Not sure if that's what's making the noise and causing my car to act strange when I rev it but it's just another thing I need to do. I swear, this car...

Could also have cracked Valve cover. I had oil going into cylinder due to crack in the Valve cover. Good idea to thoroughly check the Valve cover.

[kazbek1]

Originally Posted by Saif2018

Could also have cracked Valve cover. I had oil going into cylinder due to crack in the Valve cover. Good idea to thoroughly check the Valve cover.

Thanks for the advice! I actually replaced the valve cover last year but who knows, maybe it was defective or I could have possibly cracked it. I'll definitely inspect it though. With that, are there any leak tests I could perform on the cover after I remove it? I know I can visually check it obviously but some of the cracks are well hidden or so hairline I might easily miss spotting them.

[kazbek1]

Quick update: I've had some nasty wastegate rattle that I've been needing to fix every 6 months or so. I haven't done it in a while which you can hear in the video. I adjusted the adjuster rod as well as bringing it to the least amount of lag in MHD's wastegate fix. That seems to have helped the RPM issue. I tapped the gas to 1000 RPMs again and it pretty much went back to idle.
With the deep tone, it's definitely not coming from the engine itself. I whipped out the stethoscope and I'm 99% sure it's the alternator. Strangely though, I reset adaptations for the HPFP via MHD and the noise went away for a few minutes and then slowly started up again but wasn't a constant tone. Anyways, I'm going to keep my eye (ear?) on it but I'm hoping if anything, it's just an alternator taking it's last couple of breaths. The car performs as normal when driving and the noise goes away once I apply throttle, only to return when I take my foot off.

[Saif2018]

Originally Posted by kazbek1

Thanks for the advice! I actually replaced the valve cover last year but who knows, maybe it was defective or I could have possibly cracked it. I'll definitely inspect it though. With that, are there any leak tests I could perform on the cover after I remove it? I know I can visually check it obviously but some of the cracks are well hidden or so hairline I might easily miss spotting them.

Don't really know about any leak tests but you could clean it thoroughly, ensure it's dry, then turn it upside down and fill it with water and leave it for a while on a flat surface to see if it's leaking. Not a very scientific test I know lol

[kazbek1]

Originally Posted by Saif2018

Don't really know about any leak tests but you could clean it thoroughly, ensure it's dry, then turn it upside down and fill it with water and leave it for a while on a flat surface to see if it's leaking. Not a very scientific test I know lol

Ha yea I planned on doing that but figured I'd ask anyway. Thanks again!