Tachometer doesn't work! :-(

[Phil Payne]

> > > Bad things are going to happen if you unplug the timing sensor if the
> > > RPM sensor should miss some teeth.  I wouldn't do that.
> > > The timing sensor is actually 62 degrees before TDC on Cyl 1.
> > > If the car starts, the hall sensor is working.  On later cars,
> > > I don't think anything bad will happen if it fails while the car
> > > is running.  Not necessarily true on earlier (MAC11) cars which have
> > > a bug in the cylinder counting code if the hall sensor fails.
> >
> > Similar things happen on cars with one or more damaged flywheel teeth.  Flywheels with a single tooth broken off seem to be
> > remarkably common - I've seen three in about the last year.
>
> Does this set an error code?  I think it should, but I'd have to look
> at the MAC11 code to be sure.

Not on the MAC12D, which as you've shown is virtually identical.  It causes stumbling and even misfiring when going back on the
throttle after gearchanges - can even cause pops and bangs,

--
  Phil Payne
  http://www.isham-research.com/quattro
  +44 7785 302 803
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