E-39 sucking air

[Dan Kelliher]

2002 525i with 122k. Started out with an intermittent stalling and rough running. Replaced fuel filter. No help. Found crack in lower intake boot. Replaced and helped. Scanning tool showed o2 sensors out of range. Replaced both on exhaust manifold. Still getting codes. Cleaned MAF. No help. Sprayed cleaner on hoses and around intakes. Engine revved up, so now I know I have a secondary problem. Get the revving when I spray above the box that is wired to the MAF sensor and mounted towards the front of the engine under the intake manifold. I know that the tube from the Vanos in the front of the engine is in the area behind the box, but don't know what else is in there as I cannot see behind the box. I think that the icv is mounted towards the front of the box in the same area, but moving it around after sliding it off the mount does not affect the engine idle. Since I need to take out the air box to get in there, I want to have parts to replace what is in there and giving me the air leak. Cannot find anything in the Bentley manual that shows this area. Can anyone help me please?

[brettski]

Welcome to the Werkz.

Have a look at the exploded diagrams on the RealOEM.com Online BMW Parts Catalog it may give you some insite into the parts behind this box you are referring to.
I found a decent vacuum leak between the plastic interface that sits between the intake manifold and the throttle body. Fixing that up helped with the fuel economy as well as stabilising the performance.
If you aren't doing this already, use a nozzel on the carby cleaner spray can to focus on very localised areas.
Good luck

[Dan Kelliher]

Thanks Brettski. Turned out to be a hole in the vent hose down to the dipstick which I could see after pulling out the air box and all the intake stuff. Local parts couldn't get me parts till noon, so I ended up at the dealer for parts. Was only going to replace one hose, but a tech explained they had a kit to replace everything and explained how to do it. He was right to replace everything as the parts are plastic and everything was very brittle and broke when I tried to do anything with them. Took around 6 hrs to do everything (my neighbor helped with the connecting line into the new valve and with the intake boot on the throttle body-the only things I had major problems with). Figured I saved $ 500 as the tech said they charge 4 hrs min. for the service. I have some experience as a DIY guy, and this one for me was 4 wrenches out of five. Purrs like a kitten, runs like a lion.