Help please! Exhaust stud torque setting & lambda

Well, finally fitted the Sebring Y-piece. Very pleased with the resulting sound yet to road test though. Used City Slicker's highly-handy piccy guide. However, the process was a little bit more of a fiddle than expected and ended up loosening off the exhaust connections at the cylinders (there is probably a technical term for those ) and the balance pipe across the front of the engine.

In tightening the lot back up again, I'm rather nervous about damaging the cylinder head studs that the exhaust bolts to. The question is this: does anyone know the correct torque setting for those nuts? I've avoided using my long-handled torque wrench for fear of ham-fisted over-tightening and just given them a firm, but not full-on, nip-up with a ordinary ring spanner.

2nd'ly the lambda sensor was subjected to rather more twisting/untwisting than I would have liked during trial-fitting. Just in case, how do you know if the lambda has been damaged? What are the symptoms?

Any advice well appreciated!

BLL

Manifold to cylinder head is 21Nm.

Don't know about damage to the lambda. I expect the proper way is to read the motronic fault codes. I have seen various diy ways of doing this.You need an analogue voltmeter to be able to do it though. The codes are in the oilhead maintenance manual that Paul G has posted.

What I did notice after disconnecting the motronic to put in a BBpower chip, on restarting the exhaust was smoky at first. Then over the next 10 seconds or so the exhaust slowly cleared. The motronic loses its memory when the battery power is removed, so I assume what happens is that it takes a few seconds for the mixture setting to get back to its normal position on the first startup. This sort of agrees with what it says in the BMW workshop manual. So, maybe disconnecting the battery would give some indication.

Oilhead Maintenance manual

Cheers!

Goose - thanks for your help - much appreciated.

It has occurred to me that if the lambda is knackered the bike might throw up some kind of fault light? Probably best thing is just to ride it and see what happens!

BLL