Something I Have No Come Across Before?

[Gavtrials 0]

Hey,

Just completed another later type mi16 engine(s16) transplant into the 205 and she fired up first turn of the key but when i went to drive her thats when i got stumped as it started running crazy rough and poping and flames outa exhaust until it cut out!

 

Well after a bit of head scratching i noticed that there was a spark cuming from the ecu to the engine block on the side as thats where the ecu is mounted on this conversion(i will move it inside the car once i get a longer hose that go's from the inlet to the ecu), i held the ecu against the side of the block(thermo houseing) and suddenly idle is bang on 1000 revs and running sweet, wedged a screwdriver between the ecu and the battery to make the ecu stay conected to the block and took for a spin, ran perfect and drives amazing!

As soon as i take the ecu off the block it does all kinds of strange things so whats going on here?

I put an earth cable from the ecu to an earth mounting point but that didn't make a difference but put a cable from the ecu to the block and its sorted? so any ideas?

[Richie-Van-GTi 74 2 Cars]

try putting an earth strap from the block to the chassis, sounds like your missing the one from gearbox to chassis.