Sarge

My 535xi wagon has been acting up for a while now, giving a 'reduced power' error message with the 'check engine' picture on the display.

I've had the HPFP replaced (for the third time) about 10k ago, and the car had new turbos at 67k (presently at 109k).

The error happens when you try to accelerate at full throttle; If you drive the car in a mellow manner, it runs fine and there are no error messages - it's only triggered by demands for higher boost levels.

So, I'm thinking/hoping it's a vacuum leak, and wondering if anyone has any great suggestions for how to go about testing and/or any common areas to look for a vac leak on this car.

Thanks in advance for any suggestions/links...

- Sarge

2008 535xi wagon, 6A, 109k miles

Sarge

Answered my own question. After looking around the internet, I found several people with N54 motors in the 3-series who had vac leaks in the two little lines that run behind the oil filter. Sure enough, mine were rotted and ripped.

I went to Napa, who didn't have the cloth braided rubber lines, so I used standard rubber lines and used some of that flexible pastic sheathing to cover them and protect them from heat and oil.

It seems that when changing filters, over time, a bit of oil will spill or build up in that region and causes those vacuum lines in particular to rot away. Anyway, no more reduced power mode, and the car runs like new. I'm glad it was cheap and simple, for a change...

tonyb635

Sarge, did you take pics? I have a 535 but do not have the problem at the moment. I'm planning on changing my oil this weekend so I might want to have a look around to see if the lines are starting to crack.

Booyaazaa

Also check the vacuum lines from the vacuum canisters to the boost controllers. They tend to start cracking after about 50k miles from all the heat generated by the turbos below them. I ended up replacing all the vacuum lines under the hood a few months ago and found most to be cracking and loose. I only had 61k on the odometer too.

Sarge

Sorry, no pictures, but there's two 6 inch lines that run behind the oil filter, in front of the engine. Seems to be common. I haven't checked elsewhere yet, but it goes like new so hopefully that's the only leak at the moment.

Sarge

I should probably check that; My car has 109k on it, and the turbos were replaced at 67k, so they may be getting rotten too...

Changing all the engine oil, f/r diff, transfer case and transmission fluids right now...

tonyb635

I see two lines behind the oil filter housing that have somewhat of a protection sleave or wrap on them. The wrap is starting to look pretty bad so I might go ahead and order them. They don't appear to be vert long in length.