Speedo relation to ECU (Help)

[Dr-Rotor]

Dose anyone know if the speedo is related to the ECU? Our other FD had a reverse light issue that we were trying to sort out. My mechanic was checking to see if there was power to the plugs on the gearbox, while he was doing this he sparked one of the plugs with some gaget he uses for checking power.

We did not find the falt for the reverse lights but put the car on the dyno for a little tuning. I saw that the speedo was no longer working and the power graphes had a sign wave pattern on the top end. The fuel economy has halfed & the car has very light stutters in smooth driving at 3k in 3rd.

So this tells me the car needs the speedo reading to function properly...Could that sparking of the plug have stuffed some sensor and put the car in limp mode? It has a PFC ECU. All the fuses are fine so its not that & we have fixed the reverse light problem, it was a stuffed pin in one of the plugs under the dash.

Any ideas?