Hi - I have a 2007 MCS that I've just put back together. Had the head rebuilt (new seats, perfectly cleaned, new valve guides and stem seals, skimmed, new head gasket), new timing chain, new fuel pump, new valve cover, new injectors, good clean all over. Started up after getting it all back together 2 days ago and it ran great. Very smooth idle, revved well. I got all the rest pout together (wheel, bumper, etc) started it, and it idles like a drag car. SUPER lumpy, but not a lot of change in revs. Checked compression - it's really good. No check engine light, but code reader picked up misfire on all 4, and live data shows misfring. Changed out all 4 plugs, no change; changed out all 4 coils for known good ones, no change; changed injectors - no change; logged fuel pressure - it matches the requested values. Logged timing at idle and it is all over the place (from -10 to +8). Is this typical of vanos solenoid failure? I have another perfectly running MCS I can pull parts from to try. What else would you all suggest to try? Thx!!

 

Did you use new bolts when reinstalling the timing gear? Have you checked for vacuum leaks? The PCV hose that goes from the cam cover to the intake manifold is know to have issues - Has that been replaced?

 

I have not checked that hose for leaks, but can swap that out with a known working car. I used new bolts for timing chain kit. I checked timing again last night and its still bang on.

 

SOLVED! Vanos solenoid was plugged with debris. I swapped it with an older (but CLEAN) one I had lying around and BINGO. Super smooth idle. Need to road test still, but I think I safely say that solved it.

 

I have pretty much the same issue, did you get any codes for Solenoids ?

 

There was one, but it cleared and did not reappear, even when the car was idling horribly. I did get 5 codes for misfires, 1 for each cylinder and 1 for 'several cylinders'. It was trial and error to solve it, and it actually has come back tonight. I suspect I'll find more debris in the vanos filter screen. Both units Ive used have been the older style, that only have 1 screen. I have a new style that is fully screened coming soon, and have very high hopes that will solved this for good. If you have the same symptoms, it very well could be your vanos solenoid is non functioning or is clogged up.

Has any work been done to the engine lately? In my case, I had the head cleaned and re-built, and I think that cleaning is the source of the debris.

 

I removed intake Vanos solenoid and it was clogged up. I cleaned it and tested, it "clicks", So thats why I assumed that it works good. But as I have checked lot of other things and got no results, now I'm thinking about replacing Solenoids Just to be sure.

Once it gets little warm the engine runs great, compression is good. and with basic bolt ons, it made 180Whp without ECU tune.

 

I installed a new style vanos solenoid and test drove over the past two days - runs GREAT! Nice smooth idle and a lot of pep! Just a few more things to sort out and he'll be ready for summer. I'd recommend getting the new style vanos solenoid installed. Much better debris protection.

 

Mine already Has a new style Solenoids(you mean fully covered with mesh, right ?).
I have already ordered Two solenoids anyway and a new Thermostat, I will get it in 3 days. I REALLY hope it helps.

 

good day I'm new here. I have a question? Because I'm having the same problem. I have a R56 2009and I just changed the valve seals and now I'm having an idle issue. I have a timing chain tool. However can someone tell me what time timing is suppose to be. Some folks are telling me the first cylinder should be top dead center. Others are telling me they should all be level.

 

Since the timing gears on the camshafts are not keyed to the cam, they are help in place by the bolts and friction. The timing tools lock the cams in a known position, and when the crank is locked at the flywheel, when the chain gears are bolted in place to the cams and crank, everything is in time as designed. If the cams are not in time with the crank, all sorts of bad things can happen. Read all the how-tos you can find on the internets, and study them all carefuly to fully understand the whole process before ever starting the job. Also make sure you have all new bolts, since they are one time use only.