[snooked123]

Hi All,

I bought a 2008 328i N52 engine with 113,000 miles in the beginning of the year. It had vibration at idle to begin with but I thought it was just the motor mounts. So I replaced the motor mounts, then I replaced the valve cover with a new one but vibrations persisted. Cleaned the MAF, non exhaust vanos too plus I have replaced the front control arms .

Then I changed my gas to Shell and then to Chevron and that reduced the vibrations quite a bit so I then took out the injectors and had them ultrasonically cleaned. After injector cleaning my fuel economy has improved quite a bit but the vibrations are still there. Vibrations are much better than they were when I bought the car but they don't go away.

My tach needle is steady, the vibrations disappear completely when I turn on the AC. No check engine light.

Will appreciate any help .

**It seems that I have posted it in the wrong forum, how do I delete this thread or have it moved to the right forum? Thanks!

[E92William]

Have you been able to scan it with a proper scanner that reads Bmw specific codes? This would give an insight into the issue also reading fuel trims would aswell with live data

[snooked123]

I did use BMW scanner tool but no faults showed up. I looked at fuel trims too and it seems that LTFT for bank 1 were slightly +ve but nothing that would trigger a check engine light. The LTFTs remained slightly +ve even at 2000rpm.

[E92William]

Quick thing you can try out is unplugging the maf sensor and seeing how it runs without it. Sometimes they can go bad and without giving a code. If it can be seen in video you should record it to see how bad it sounds if at all
This is a bit weird since your fuel trims are good

[snooked123]

Let me try that and record it as well. I am kind of at a loss at the moment, I am thinking of doing a fuel pressure test and just for the heck of it a compression test too.

[colorado.e9x]

PCV has a common problem with the diaphragm tearing. Makes a vacuum in the crank case, an idle surge, as well as oil loss. Mine needs replaced as I have all these problems

[snooked123]

Connecting or disconnecting the MAF has no effect whatsoever on the car except for triggering the check engine light. What does that mean?

@coloradio.e9x: I replaced the valve cover so I am hoping that the PCV is not the culprit.

[juld0zer]

Manual or auto?
When were the plugs changed last? What plugs are installed? What coils?

I find the N52 very tolerant of marginal ignition components, ie it takes a complety dead coil or broken plug to bring on the engine light but it will demonstrate quite obvious symptoms

[3002 tii]

This may be covered under SULEV

[snooked123]

It's an automatic. I changed the plugs about a 1000 miles ago with NGK iridium but the coils are very old.

It's not SULEV

[lowrydr310]

What engine mounts did you use when you replaced them?

[snooked123]

I used lemforder

[coriolis14]

Originally Posted by snooked123

Hi All,

I bought a 2008 328i N52 engine with 113,000 miles in the beginning of the year. It had vibration at idle to begin with but I thought it was just the motor mounts. So I replaced the motor mounts, then I replaced the valve cover with a new one but vibrations persisted. Cleaned the MAF, non exhaust vanos too plus I have replaced the front control arms .

Then I changed my gas to Shell and then to Chevron and that reduced the vibrations quite a bit so I then took out the injectors and had them ultrasonically cleaned. After injector cleaning my fuel economy has improved quite a bit but the vibrations are still there. Vibrations are much better than they were when I bought the car but they don't go away.

My tach needle is steady, the vibrations disappear completely when I turn on the AC. No check engine light.

Will appreciate any help .

**It seems that I have posted it in the wrong forum, how do I delete this thread or have it moved to the right forum? Thanks!

hey snooked123 - were you ever able to figure out what was causing your vibration? i'm having the exact same problem and it's been driving me nuts trying to diagnose it.

recently had a shop do my motor mounts a month ago and my plugs were changed 20k miles ago. coils are on the older side though.

[crashoverride]

These cars go through coils faster than any car I've ever owned. They're cheap and need to be replaced whenever the plugs are replaced... not written in any manual just needs to be done... Both posters reporting same problem and both not touching the coils... not guaranteed to solve but well worth trying

[coriolis14]

Originally Posted by crashoverride

These cars go through coils faster than any car I've ever owned. They're cheap and need to be replaced whenever the plugs are replaced... not written in any manual just needs to be done... Both posters reporting same problem and both not touching the coils... not guaranteed to solve but well worth trying

I'll give this a shot, but my understanding was that if it was the coils going bad the car would perform badly under hard acceleration/revving the motor out.

The engine is smooth as butter once I start moving. It's only when i'm parked or stopped in drive (I have AT) where I get this issue. Let me know if I have that wrong though.

[sabino56]

See if it idles rough with belt removed. I had a rough idle due to a failed over running clutch on alternator. With belt off, you can check if alt pulley is ok.

[coriolis14]

Originally Posted by sabino56

See if it idles rough with belt removed. I had a rough idle due to a failed over running clutch on alternator. With belt off, you can check if alt pulley is ok.

I ordered new coils and will replace them, but I've never heard of this before. Is this the part you're referring to?

[sabino56]

The pulley is called a OAP, it allows alternator to overrun belt/crank when needed to minimize dynamics in rotating mass/serpentine belt.

“Rough” idle is a big category so no clue if yours is something which could be caused by something like this or no. One persons “rough” is another’s don’t care/notice.

You seem to be running it of ideas so I just mentioned as it’s easy to check if the same roughness is present with and without belt. If smooth without belt, easy to check the OAP on alternator.

In my case, it was a knocking sound plus some variation in idle speed. I never expected the alt pulley could cause something like that. I was thinking maybe my a/c or pwr steering pump were acting up perhaps so only found it by noticing things where good without belt and then trying various belt length combinations to isolate the problem to the alternator. The thread is here and a video of the “rough” idle it caused for comparison to yours.
https://www.e90post.com/forums/showthread.php?t=1962637

Good luck!

[coriolis14]

Originally Posted by sabino56

The pulley is called a OAP, it allows alternator to overrun belt/crank when needed to minimize dynamics in rotating mass/serpentine belt.

“Rough” idle is a big category so no clue if yours is something which could be caused by something like this or no. One persons “rough” is another’s don’t care/notice.

You seem to be running it of ideas so I just mentioned as it’s easy to check if the same roughness is present with and without belt. If smooth without belt, easy to check the OAP on alternator.

In my case, it was a knocking sound plus some variation in idle speed. I never expected the alt pulley could cause something like that. I was thinking maybe my a/c or pwr steering pump were acting up perhaps so only found it by noticing things where good without belt and then trying various belt length combinations to isolate the problem to the alternator. The thread is here and a video of the “rough” idle it caused for comparison to yours.
https://www.e90post.com/forums/showthread.php?t=1962637

Good luck!

thank you - i changed out the coils and the accessory drive belt since i noticed a squeal developing whenever i start the car up.

there has been no change to the idle problem, but the squeal on startup is still there. i think the problem (for both the squeal and the idle issue) might be the alternator pully. i'm going to do that job next weekend and see if there's any improvement.

[coriolis14]

Originally Posted by coriolis14

thank you - i changed out the coils and the accessory drive belt since i noticed a squeal developing whenever i start the car up.

there has been no change to the idle problem, but the squeal on startup is still there. i think the problem (for both the squeal and the idle issue) might be the alternator pully. i'm going to do that job next weekend and see if there's any improvement.

update here: no resolution unfortunately.

i installed a new alternator pulley about 2 weeks ago and noticed that the quality of idle vibration i'm experience has softened (it doesn't jolt the car as harshly when it happens before the alternator pulley was swapped) but it's still there and very noticable.

i'm honestly at a loss as to what is going on here. clearly it seems to be related to the drive belt since installing a new alternator pulley changed the quality of the vibration. maybe it's the alternator itself?

i don't think it's the power steering pump since i've tried turning the wheels lock to lock at idle and it doesn't cause any problems or vibrations. i replaced the idler pulley a year ago so i don't think that would be causing this either.

[sabino56]

Bummer you still have problems.
Did you ever see if it idles rough with belt removed?

[coriolis14]

Originally Posted by sabino56

Bummer you still have problems.
Did you ever see if it idles rough with belt removed?

I haven't tried that yet - wouldn't that kill the battery pretty quickly since the alternator wouldn't be spinning?