I am a new to mini owner, car fanatic, purchased 2003 R50 base, in immaculate condition, no issues form an older driver ( only summers)
two tanks of gas in and engine light comes on at extended idle (1-5 min) with the ADC light unrelated. 304 generic misfire code

things I did... changed plugs and cables ( now back to original cables just in case)
I also ran some engine gum out... but still on same tank. trying to burn through tank.

I took to a bmw/mini specialty shop and they tried everything i did and did do a compression test and cylinder 4 is a little low....

here is the wierd part

If I clear the code and start the car keeping RPM at 1000 or higher no codes... I have driven over 200km like this now, I know if I were to idle down I would likely get the code.

if I get the code and shut off and start up again it is fine until an idle.

the shop said drive it and see (the alternative is potential unconfirmed exhaust valve issue = head rebuild =$$$$ more than I paid for the car)

car drives really well which is weird

any thoughts on what else it could be?

 

Check for corrosion on the coil pack. Especially the #3 terminal.

 

thanks I have cleaned that up, but still when car is allowed to idle it will prompt the misfire cylinder 4 code, also in unrelated code will be the adc code. none of these occur if i start and drive car and there is no idle or misfire issues while driving??

 

Why idle it extensively?
Since it is new to you, I'd run it as is for a week or two & find it's little foibles - it sounds as though it needs some exercise.

 

Thanks that is my plan right now, I am driving it daily, I cleared the code this morning drove it 50 km without issue and shut off upon arrival.

I know that cylinder 4 has lower compression, but when driving and rpms over 1000 car runs like a dream. plan is to drive it for a while and see it exercise is what it needs.