morning all

i have a 2003 r53 with 73k, i have owned it for about 6 months,

my expansion bottle was suffering from the normal crack they develop so i ordered a new one to replace it, i also noticed the coolant was a brown colour (rusty colour/tea colour)

so i changed the bottle yesterday and flushed the system with new coolant and distilled water. i only had to disconnect the back ht leads and power to the coilpack so i could get the bottle out.

started the car up and sounded fine, i then took it for a drive and the car misfired under load. came back checked the spark plugs they looked ok buy fitted 4 brand new ones. took it out and seemed to have cured it for about 10 seconds then started misfiring again under load. so thought i might have damaged the ht leads by removing them, so replaced the HT leads and fitted a brand new coil pack. the car now misfires all the time and eml light has come on showing misfire on cylinder 4.

can anyone help, im fearing the worst that the head gasket has gone, maybe the old coolant had addative in it or something (leak stop). now ive flushed it its getting into cylinder 4? i did have the bleed screw on top of the raditor open when i was filling back up to get rid of air.

really naffed me off as a simple coolant change is going to turn out expensive,

 

Are the leads clean on the coil pack? They tend to corrode over time and could cause this.

 

I've fitted new sparks, Ht leads and coil packs today and still got
The same issue

 

Argh. It will turn out to be something silly. Once you sort it out. Any chance you used antisieze on the spark plugs. Occasionally people report trouble with that as some interferes with the grounding. I would also check the low tension connector on the coil pack to make sure a pin wasn't bent. Did you do any other work? Hoses, PCV valve, etc?

 

How'd you flush the coolant? Were you near the map or tmap sensors? Could those wires be loose now?

 

There's no way the head gasket blew from flushing the coolant. Is there water in the oil? Exhaust a funny color?

Double check any and all connections. Are the plug wires in the right order ? Haven't tried it on a Mini so I don't know if it will even run out of order.

It ran fine before you worked on it, so unless it's a crazy coincidence you probably just accidentally loosened something up.

 

I know it's strange. I'm going to change the temperature sensor tomorrow. Can only think changing the coolant may of effected it somehow? And now it's not getting correct readings.

 

When changing the bottle
I did disconnect 3/4 lead and the main coil pack power lead. But all that appears to be fine plus I've tried new coil pack and Ht leads on it. Is there any way to test the connector to the coil pack? I think reds ingnition live the the other 2 blacks are for each pair of coils

 

did you put the wires to the corresponding cylinders?

 

If you've got an old fashioned inductive timing light, you could clamp that around wire #4. No timing mark to check against, but you should see it triggering/flashing.

 

Yes

 

Inspected the wires. The insulation could be brittle and when disturbing them they could have been damaged.

 

Car is fixed. Changed the coolant temp sensor and did a flush again and now running sweet as.