Originally Posted by Nubodi Automotive
...Ive had this exact problem twice on Z3's...
Many thanks for your perspective.
I've posted on a number of forums and checked with some ECU specialists but yours is the first reply with direct experience.
OBD is not throwing any codes to point to the cam sensor which has obviously confused the situation but they are a known problem.
Your advice about cheap replacements is well taken- I don't relish stripping the VANOS gear repeatedly for the sake
of a £30 difference between the oriental ones and the Bosch/Delphi/Bilstein equivalent. That experience is repeated on several BMW forums.
One ECU option that does sound interesting came from EndTuning-
"I can delete the immobiliser, but that doesn't sound like the immobiliser to
me. You should have the M52TU engine, and they shouldn't fire up at all if the
immobiliser has gone out of sync. It's possible a throttle problem could
cause an issue like that, or maybe cam or crank
It is possible for me to read the stored codes on the ECU, so if you do want
to go down the un-immobilising route, I'd be able to look for codes.
Immobiliser deletes are £50, and they come with raised rev limiters and
there can be options like a harder cut limiter, over-run burble
I like the sound of that last bit !!!