[bullion]

I know this topic has been covered in the past, but I want to put my story out there for comparison and for comment. I have a 2008 BMW 335xi (6-speed manual) that I bought earlier this year with approximately 37,000 miles on it. The car is certified pre-owned. I have owned the car for approximately 9 months and have only put about 4,000 miles on the car in that time. Within the first month of owning the car it started misfiring horribly on random cold start ups. Oddly enough it only did this misfiring routine once every few months. So of course the dealer could never reproduce the problem when it was in the shop. All they verified was that there was a misfire on cylinder #4. Past service history will reveal that my car has had two new fuel pumps and at least 6 new fuel injectors. During the time that I have owned the car, the dealership has tried putting a new coil pack on cylinder #4 which proved not to be a solution to the problem and most recently they pulled/replaced the valve cover to clean the intake valves. Apparently the valves were pretty gunked up. Well, after they cleaned the valves, the car ran great for about 6 months. It is now back in the shop and they have discovered the valves are gunked up again! BMW engineering and technical is involved at this point to figure out what is going on. I'll keep you all updated as to what they determine the cause to be, but in the mean time, feel free to comment!

[tscdennab]

I am not an expert on this, but maybe there is a high amount of oil entering your intake manifold and clogging up the intake valves. This could come from worn turbos which could be leaking oil. The previous owner may have abused the car.

[Jeff@TopGearSolutions]

Direct injection is known for this.

You might want to invest in an oil catch can.

I heard sea foam only does so much but maybe every 3-5K look into a seafoam treatment or similar.


To the above poster, I doubt abuse is the culprit here, infact if anything it would help. Driving these cars like a grandma is exactly what you dont want to do. A good amount of WOT here and there will help heat things up and get things out.

[Trojan4evr]

Originally Posted by JPSlick

Direct injection is known for this.

You might want to invest in an oil catch can.

I heard sea foam only does so much but maybe every 3-5K look into a seafoam treatment or similar.


To the above poster, I doubt abuse is the culprit here, infact if anything it would help. Driving these cars like a grandma is exactly what you dont want to do. A good amount of WOT here and there will help heat things up and get things out.

+1111

[bullion]

Trust me, I drive the car the way it was meant to be driven!

As for the oil catch can...I installed the BHA oil catch can immediately after the first time the dealership cleaned the intake valves. Less than a couple thousand miles later and the problem is back. I obviously have a different problem. On a side note, the dealer wasn't too happy about the oil catch can. It took me a while to convince them it was a good modification. None the less, they are past this issue now.

[bullion]

I finally got the car back yesterday after the dealer having it for over a month. After a handful of testing, they determined it was a faulty fuel injector. I think this caught them off guard since my car already had the updated injectors and fuel pump. None the less, I hope they got it right this time!