You might be thinking of the replacement engine I put in
@Nodzed &
@t-tony . It was fine when it left the donor car. In the receiving car it would only run on 5 cylinders.
It turned out to be the pin on the DME that controlled the firing signal of the cylinder. It was corroded. No firing signal reaching the coil pack.
Logic suggested that was the cause of the original engine blowing it's guts out of the sump. Fuel built up, no spark, compression raised and then boom. It was bought like that so I don't know the history first-hand.
It's well worth pulling the DME out and inspecting for damp ingress and pin corrosion. That's something everyone should do bearing in mind the possible consequences...
But as always, best to start with the error codes. Mine reported as a misfire on cylinder 4 and that was it.
If it's not that, happy to try and make further suggestions if we know the error code. But I'm no ignition/engine expert. Just ruthless at getting to the bottom of any problem so it doesn't beat me