So I have this m54 that's been converted to single vanos and being run by m52b28 ecu and harness. it works but I have a vanos stuck timing problem. I'm thinking I have the secondary chain a tooth off but I want to confirm before I tear more down. here's my first hunch, the intake cam is retarded by one tooth so the computer tries to correct by advancing the cam timing, I get the vanos mechanical fault code 212 at startup. as if its trying to correct, gets it as best as it can, and it runs well enough, it starts up with a very rough idle, while the computer is computing where the cam is, about 30 seconds later, it figures it out and smooths out by advancing the intake cam timing as far as it can, which still isn't in spec, but close enough to run well enough. since I have the exhaust cam from the dead b28 i cobbled this all together with, and the oil control passages to the exhaust vanos piston blocked. as I can't exactly set vanos correctly "by the book" due to the fact its half m52 half m54. a few things I want to confirm, and ask, first when both cams are locked in the fixture and pin in the flywheel, are the cams at tdc? 2ndly I'm seeing -16* of cam timing at idle, should that number be closer to 0? and then roughly 12* advanced above 3500ish rpm? I'd love to see what its stock routine of cam advancement looks like as well if anyone has a map from a tune. Finally, does anyone have any idea where the vanos piston should be (roughly) in its travel when its setup correctly? mine is completely bottomed out, I measured vanos travel when I set this the first time and it checks out, I am able to operate it to its full range, on air pressure. so I've ruled out the spindle valve and piston. .So I think the main cause to be the intake is a tooth retarded. anyone have any thoughts or tips?
