08 535xi acceleration shudder/pulsation
 

I just bought an 08 535xi (6-speed manual) from a BMW dealership 3 days ago. I LOVE this car so far and it is mint and loaded. I specifically wanted a 6-speed because I used to have a 2011 328i which was also a stick. The 3 series was NOT AWD and was very smooth through every gear. The 08 I just picked up is quick but not smooth like the RWD 3 series. It seems to have a "miss" feeling or "pulsates" very slightly on hard acceleration. The car still moves perfectly and is fun as hell to drive. Is this due to the car being AWD? I've never had and AWD car before. The car has 76k but was dealership maintained with service records. It shows the spark plugs being changed back at around 50,000 miles. I'm just looking to see if anyone has any insight on this. I have the dealerships powertrain warranty for the next 3,000 miles or 3 months. Thanks!!

Most likely carbon build up on the intake valves -- an unfortunate side effect of direct injection (no fuel to wash them clean). My dealer walnut blasted the valves for me under warranty at 40K miles but I hear the cost is usually between $600-800.

OK...I've been hearing that on a couple different forums. The dealer gave me a 3 month/3,000 mile power train warranty. So hopefully they'll honor their word. Seemed like an awesome dealership where I purchased it.

I agree the intake valves are a likely culprit at 76K, but also have them check the injectors/HPFP as well, if it hasn't already been done! It's unlikely that it's the HPFP, but even "functioning" injectors may need to be replaced if they fail the diagnostics test that was part of the bulletin. This has fixed similar issues for some.

You should not feel anything different due to being AWD - no pulsing, shudders, nothing.

The dirty valves on the intake side is due to the fact that BMW spits oil on the intake valves. You can fix that issue from ever happening again by installing a catch can so the oil never touches the valves again.

I think the consensus on n54tech and e90post is that the OCC only delays the inevitable, as it doesn't catch everything...and the lesser designs don't even do that! Much of the oil and unspent gas are suspended as crankcase vapor. Either way, eventually you're going to need to clean your intake valves! There are plenty of tear down threads from people who were using OCCs with pics to prove it. If you have the time, there are several threads detailing how to perform the cleaning by hand, but it is very time consuming! Walnut blasting is definitely the quickest method if cost is not an issue...

Exactly. I have a BMS OCC (which is one of the better OCC's out there) and still had heavy carbon build up. All direct injection engines suffer from carbon build-up to some extent and some manufactures have taken steps to minimize it. BMW doesn't seem to be one of them or at least they didn't take steps to addressed it adequately with the N54. Maybe they did with the N55..not sure.

I drive 09 535x drive. I had the same feeling as you do when I was accelerating. Found out it was the HPFP which was replaced by dealer as it was a recall on it....

Best is to take it back to the dealer and let them know there is an issue. Hopefully there are some fault codes stored for them to figure out whats going on. If it is the hpfp the good news is its covered by bmwna for 10 years or 120k miles, whichever is first. My e60 is at the dealer right now with a similiar issue to find out all 6 of my injectors are toast and are being replaced.