318iSE e46 Touring - Valve timing problem
've recently refitted the cylinder head on our M43 engine (chassis number JK87372). Unfortunately the head had to be skimmed twice because I dropped a valve on it during reassembly.
Initially the engine started and ran quite sweet but after a short while became a bit rough especially on start up and tick over. A diagnostic test showed the camshaft position sensor was faulty and when tested with a DMM it was open circuit between pins 1&2 and 2&3. I will have to get a another one which may cure the problem.
However, I'm concerned that the valve timing may be out. When I set the valve timing I used crank and camshaft locking tools and positioned the camshaft sprocket back in its original position, using markings on the various parts to line things up; and then checked the factory marking arrows were in the correct place.
I've since been told that it is possible to get the valve timing wrong after head skimming because skimming the head results in the camshaft being very slightly closer to the head and hence slackens the chain. If not adjusted out, this slack will be taken up by the crankshaft sprocket as it rotates forward; resulting the camshaft being slightly behind/retarded of where it should be.
I've done numerous web searches but found nothing that helps, making me feel what I've been told is not really true enough to cause a problem.
Can anyone shed any light on this and advise how to set the valve timing correctly if the above error is true?