Weird MC engine problem - resolution

[Phil Payne]

First of all - my respect to the guys at Turbotronics who finally nailed this problem using
'first principles'.

a) The ignition switch is definitely 'iffy' but not the ultimate cause.

b) The main reason for the sudden expiry was a blocked catalyser.  Rodding it out improved
matters.  The cat is not a legal requirement on this particular model year.

c) What was fooling us - the TDC sensor had been damaged by an overzealous tie-wrapper -
damage to the screen and one of the wires.  Sometimes it worked - sometimes it didn't.  The
killer was - when it wasn't working it was picking up a spurious signal by induction from a
plug wire!  No codes - the ECU thought it was seeing a real crank sensor signal - the timing
was just so far off that the engine ran backwards.

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