How would the car behave if it wasnt getting that speed impulse if it was a Mk2 ecu? would it judder randomly for a period of time then go off again for as long as you drive the car? because thats the problem im getting.

Im well in the belief that the engine has been changed for a Mk2 engine and box and theyve swapped the dials over so they havent bothered with the speedo cable.

Three reasons for this

1: The cambelt cover had 45,000 written on it in tipexish stuff.
2: The cam cover has "Zetec16v" instead of "DOHC16" which I think is odd for a 95 "N" car
3: There is a hole in the plastic behind the dials where the speedo cable would have come through (for all I know the Mk2's could still have this)

The problem is I dont know whether its using a a Mk1 or Mk2 ecu but I suppose either way it could be causing the juddering.

Mk1 ecu not liking the MK2 engine differences
Mk2 ecu not receiving speed impulse

Where would an electronic speedo cable come from? the ecu? Im a bit stuck for how to resolve this.

I could fit an analog sensor, cable and dials but that wouldnt help my juddering problem?