[Luke784]

Hello,

I'm trying to figure out what I'm missing/messed up after replacing some gaskets in my 2008 335i with ~130k. Previous to the job the car was running great on an MHD Stage 1 tune with the exception of the fact that it was leaking oil from the valve cover gasket and oil filter housing gasket.

So I pulled the valve cover off and replaced the gasket as well as the oil filter housing gasket. While I was there I also replaced the oil cooler gasket and o-rings as well as the intake manifold gaskets after I cleaned the carbon off the intake valves.

I put everything back together and am fairly certain all connections are made. I didn't see any breaks in the vacuum hoses but I'm not ruling out that some could be cracked.

The car starts and runs/idles fine while still cold (should add that I did the auto bleed procedure and added coolant before starting) however it will not make boost and once it gets even a little bit warm it will start running progressively rougher until it finally quits. I have cleared the codes a few times and the ones that seem to persist are the following:

2A98 - DME: crankshaft - inlet camshaft, reference.
3100 - DMW: boost-pressure control deactivation.

A couple other things that might affect this but I'm not sure.

1. When I cleaned the valves I bumped the starter using a test lead to open/close valves I was working on.

2. I'm fairly certain I have dropped a socket down onto the belly pan of the car but I cannot find it. Not sure if this could be causing noise for any of the sensors.

Anyway, has anybody experienced this? Do I need to replace all my vacuum lines? Could it potentially be something worse? Thank you in advance for the help.

[Tambohamilton]

I'm no N54 expert, but I'd say check all wiring and connections (particularly inlet cam sensor and boost solenoid). If everything checks out, test the vacuum system using a vacuum pump (£13 on eBay, UK), and/or replace vacuum lines as necessary.

[Luke784]

I think that’s exactly what I’m going to do. I have already checked connections but I’m going to get my buddy for a second set of eyes and see if we see anything loose or missing. If that doesn’t turn up anything I’ll probably replace all the vacuum hoses since they probably need doing anyway and that will rule them out as the problem. Thanks for the response!

[Oolien]

It can be anything from misplaced timing, bad sensors, vacuum leak to failing bearing ledges

with those codes i would check
-VANOS solenoid
-slipped timing
-bearing ledge/hook ring
-VANOS adjusting unit (the camshaft sprocket/VANOS hub.

[Luke784]

I thought I had the problem solved for a little bit. I went through and replaced all the vacuum lines that I touched during removal of the valve cover. This had no effect on the problem whatsoever.

I then removed the VANOS solenoids and cleaned them out with some parts cleaner. When I reinstalled them I swapped the intake and exhaust solenoids.

Upon starting the car everything seemed great. It was running smooth and I let it sit and idle to get up to temperature. Nothing was wrong so far so I decided to take it on a test drive. Went a short distance at around 30 mph (less than 3 miles) and suddenly got a check engine light and a whole bunch of new codes:

29CC - DME: Combustion misfires, several cylinders
29CD - DME: Combustion misfires, cylinder 1
29D0 - DME: Combustion misfires, cylinder 4
29D2 - DME: Combustion misfires, cylinder 6
2A82 - DME: Combustion misfires, cylinder 6
2A82 - DME: VANOS intake
2AAF - DME: Fuel pump, plausibility
3100 - DME: Boost-pressure control, deactivation

So my next course of action is to order new VANOS solenoids and change the oil when the new solenoids are installed. If that doesn't work it looks like the valve cover has to come back off again to check the camshaft system components which I'm not excited to do...

[e90 Second Incarnate]

Are you sure you ruled out a vacuum leak? Did you replace the manifold gaskets? Can you check fuel trims to look for a lean condition?

[Luke784]

I finally got this problem sorted out and wanted to bring this thread full circle for anyone who might encounter this in the future. It was a pretty simple fix in that I just replaced both VANOS solenoids and changed the oil. The car now runs fine and probably didn’t have a vacuum leak at all but I’m not upset I changed out the old, brittle hoses.

I changed the oil on the advice of this video (https://m.youtube.com/watch?v=YktIgslaoIQ) where they change the oil and swap the VANOS solenoids before considering more intensive repairs like cam ledges. I tried cleaning, testing and swapping my old solenoids but the problem persisted which made me nervous. I went ahead and ordered two new ones anyway since as far as I know mine are the originals and are well beyond their useful lives.

I suspect that both solenoids were sticking due to a few potential causes. First the car’s oil cooler gaskets were leaking and this would allow for coolant to mix with the oil. Second (ashamed to admit this part) I put an additive in the oil to help slow the leaks before I fixed them. It did work decently but I think once the car sat for a few days without running it might have gummed up the solenoids. Hopefully this doesn’t affect other things like the turbos but it should be gone from the system now.

Anyway, thanks for the suggestions and I hope this helps someone in the future who is having this problem.

TLDR: New oil and VANOS solenoids fixed the problem.