I find the whole concept of valve clearances being adjusted to fine tolerances disturbing. What is not clear is whether they are closing them up or opening them out--opening them out seems logical--- BUT many engines operate a decompressor system that slightly holds OPEN one exhaust valve to allow a bit of leakage and LOSS of compression simply to allow the starter to turn the engine over at a reasonable rate--and that ALLOWS it to start. I agree that excess blowby or valves with NO clearance reduce compression significantly to a point where combustion at starting revs gets difficult. Decompressor systems kick out once the engine has fired a couple of times and the revs have built to an idle level and the system is therefore no more in operation. Did the BM crank ok but NOT fire? Certainly battery voltage on cranking does affect modern systems and the injection process doesn't operate if its too low. If the engine simply won't turn over then it sounds like a battery issue as has been described, or a sensor is getting too hot and failing--but that should show a fault code?---not allowing the ECU to give an ok signal and allow cranking. Oil getting stuck somewhere it shouldn't !! IMO the most stupid comment I've ever heard from a so called mechanic--utter rubbish. Personally I would pursue BMW direct to get a better explanation(but also change the battery anyway).
Additionally just watched the vid and its the INLET profiles that are shifted between part load and full load which makes sense--although the engine doesn't exactly rev its nuts off anyway, which is usually the reason for VVT and changing cam profiles--gas travels at a maximum of sonic velocity on the inlet side irrespective of engine revs and too much overlap at part revs allows a bit of reverse flow and poor cylinder filling . Also on the invoice they can't spell for one and the EXHAUST clearances were adjusted TIGHTER--and not related to the VVT, and also I assume that the clearances were in spec anyway--most odd as I said above.
BMW GSA1250 Spurious Fault Codes and Intermittent Non-Starting.
Re: BMW GSA1250 Spurious Fault Codes and Intermittent Non-Starting.
Thanks for the comments and info - all interesting stuff.
English isn't Joanne's first language BTW - though if I hadn't met her, I agree, it wouldn't look very professional.
I've been out a few times now and done a good few miles - so far so good.
Starting up does sound much sharper and more positive.
If I didn't know different, I'd say it sounds like a bigger more powerful battery has been installed
I stopped the engine and started it again as much as possible, at suitable junctions etc
and had no hint of the starting issue.
Here's hoping...............................
