Pete Guthrie wrote:
hi all, our 1989 bmw eta, has a problem..
3500 rpm is top whack, instead of 4500 rpm, which is actual rpm limit, the fuel cut kicks in, very very odd
A faulty or erratic bellhousing flywheel sensor can cause almost exactly what feels like fuel cutout, usually around 3500-4000 rpm. In post cases though, the car will occasionally blast past the tumble and get to high(er)rpm.
First thing to do on the Eta is swap the flywheel and the reference sensors on the bellhousing and see if the problem changes. The 2 sensors are identical -- one watches all the flywheel teeth go by (in lieu of a real crank sensor), and one watches a steel dowel on the flywheel whizz past for crank angle.
Yes I know this from personal experience

_________________
Mike Whitney
whit32@gmail.com, 919-454-5445
V10, V8, V8t, I6, I6, V6, F4t, I4, I4, I4, I4, I2, 1, 1