BimmerFan52

A rough running engine could be a lot of things so it can be tough to track down (fuel filter, bad gas, fuel pump, spark plugs, plug wires, vacuum leaks).

Generally, a vacuum leak will generate a CEL, but not always.

I would first try a bottle of injector cleaner. I like the Techron brand. Mix with about 12-15 gallons of gas and run it out (don't dilute it by adding more gas until the mix is almost gone).

Vacuum hoses or seal points could be leaking. Leaks break down into two parts - metered air leaks (leaks between the MAF and the throttle body) and vacuum leaks (after the throttle body).

The computer depends upon a vacuum to be able to accurately meter the fuel/air mix and any significant loss of the vacuum will cause the engine run differently. Extra air that is not measured entering the engine will cause the engine to run lean. To test the results of a really bad leak, try removing the oil filler cap while the engine is running - it will nearly stop.

The vacuum leak can be anything from a small hose disconnected or loose to a tiny crack in a hose. Vacuum leaks can be extremely difficult to find and diagnose. Sometimes a smoke test is employed as the vacuum leak will "suck" air, and a safe smoke source is held around the engine to visually see the smoke being "sucked" to the point of the leak.

A worn or poorly fitting oil filler cap can introduce a leak. With the engine stopped remove the cap and examine the cap gasket. With the engine running and the cap in place take plastic food wrap and cover the oil filler cap and try and seal against the valve cover. If the engine smooths out it may be your cap.

Be careful handling all hoses and pipes as the cars that have reached 8-10 years old or more can have very brittle components (the reason many leaks exist in the first place). Certain connections are a nightmare to replace because major components need to be removed to reach one end of the pipe.

kskane

After closely monitoring, I noticed the vibration gets twice as loud in noise and feel if the AC is turned on. Is this problem actually related to AC by any chance? Also, apart from mechanical tensioner on AC and alternator what other pulleys could cause noise or vibration or is suggested to be changed?

Nika

Yes, I have the same vibration. When the Car is parked I can hear it on pass side dashboard mostly, when I change gears, vibration also changes. when I roll the car, it quites and goes on as I go on bumpy road at about 2km/h. I have 530d
Could be pulley I suspect due to vibration getting bigger when turning the steering wheel.

kskane

Thanks Nika to confirm you have the same issue. Today I discovered something else, When this vibration occurs, if you actually move the gear into Parking, the vibration either disappears or calms down like a beast. When I moved the gear back into drive, the vibration started again, and then increased with the AC on. So I am not sure if it is a combination of Transmission and AC, but I don't know what is it and it is driving me mad guys , okay I am serious.

Well another friend of mine from another forum posted that he already changed the pulleys and it did not help, so I can't say anything. Although, I have bought new tensioners for engine and AC and might change it this weekend anyways, as it is due on mine at 146K.

Nika

Looking forward to it! As my Flywheel broke off half month ago, and even though it can be just coincidence, it might be because of vibration... I am very desperate to fix it as well...
kskane, does moving your steering wheel when stationery, affect the vibration?

kskane

I have not noticed the steering wheel movement related to vibration, but in these cars you can't really say, so I will monitor it from today.

Changed the engine tensioner today, the old one was gone to the freeway and I never knew, lucky I changed. That has not helped the vibration as confirmed by a friend earlier as well.

To all the guys having this problem, can I request to post what engine oil you are using in your car, specific brand and type e.g Castrol Edge Titanium 0W40 etc. I am not sure if this problem is related to engine oil or not?

I am currently using Mobil1 0W40.
Another friend of mine is using Mobil1 5W40 BMW LL01

Nika

Definitely not oil related. I use BMW longlife 5-30...

Exhaust manifold or exhaust mounts? Also I heard that exhaust can damage (next to exhaust pipe b in the picture. We need to sort this ASAP... I will later post pics of damaged flywheel.

kskane

Thanks Nika, look forward to your next update. In the mean time can I ask the BMW LL 5-30 oil you are using is from Mobil1 ?? I know it is bizzare to believe it is oil related but does not harm to find out what everybody is using.

Nika

Well, I would say it is Castrol, because I buy it in the dealership... I think of taking the exhaust off just to see if it is indeed because of Flex Joint.

There it is, as promised.. Beautiful flywheel broken. I hope vibrations didn't lead to this problem and It was just out of nowhere. I am scared to Redline the car after this happened, honestly...



BTW: I changed both Engine Mounts to OEM BMW a while back... so can't be mounts.

kskane

Hey Nika, can you post the image again, I can't see it from the link. Thanks.