Hello

I am new in the group, appreciate your support.

I have a 2009 mini cooper base N12. I have rebuilt the engine by replacing the gaskets, cylinder rings, block and head resurfacing, water pump, thermostat, etc..

Engine started perfect, running smooth as expected but after 15 minutes running at idle got misfiring at cyl. 3. Ignition coil got melted inside. We replaced the coil and spark plug but no more spark in this cylinder.

We think ECU got damaged because not sending ground pulse to activate the ignition coil 3.
Pending to your comments and advise before purchasing a new ECU.

Thanks!

 

I've heard that when the ground cable in the front middle of the valve cover is not making a good connection, serious problems like this can happen. Are you sure this connection is a good and solid?

 

#3 cylinder misfire is a very common & mysterious failure point, at least on early MINIs.
Clean the #3 contact & plug wire thoroughly - perhaps replace all the plug wires since the coil is new.
(Are there separate coils on an N14? If so, this may not be relevant).

 

If indeed your ecu is damaged, you dont need a new ecu. Find an ecu with matcyong part numbers amd have it cloned. You can use Ktag or fg galetto.