Hi I hope someone can help me.
I have a problem with my X type 2ltr 2002
The engine runs fine but as soon as i put the heater on it starts to sound like it is missfireing and the engine malfunction light comes on on the dash board

 

If you keep the engine at 2000rpm and then turn on the heater, does it still sound like it is misfiring? It could just be that your idle isn't high enough for the excessive accessory load that the heater places on the engine.

 

argoose, from what you are describing, you have a wire crossed some where. has someone recently done some work on your car? if so, I would take a look in that area to make sure that they haven't pinched a wire or something (this is especially true if they were doing dash work). After that, I would do some looking around under the dash to see if you can spot a wiring harness that is getting pinched and it is leading to wires being damaged.

The two systems are not tied to each other. So, to have a condition like you are saying, some wires are touching that shouldn't be.