Hi,

I'm having a strange problem... My R56 Cooper S is misfiring on WOT, now its not happening all the time and I'm still in the process of figuring out what conditions cause it. But so far I've had it happen to me in 4th and 5th with WOT and when I'm about to hit peak power. I've changed the spark plugs and it seemed to cure the problem but it has started to raise its head again after about 5k miles. Is there anything else i can check? or any ideas on what might be causing it?

Any help will be appreciated!

Ben

 

This was happening to me due to the gas availble in my area- 99% of the gas stations have 10% ethonal or less in there 93 octane- so I found one station without ethonal and the misfire at WOT went away-

 

This might supply a clue:
P-Torque'd 230bhp & 260lb/ft

maybe your gas isn't high enough octane for the boost/timing you are running. You may want to have Will dial the tune back a little.

 

I was thinking that, I have used TESCO 99 Octane (UK) fuel the whole time I have had my car though so its not like I'm using a crappy fuel. I talked to Will @ P-Torque about this problem and he said that this tune is basically the same as what he has put on all R56 Cooper S's and this is the first he has heard of a problem like this. I'll throw him an email asking if turning it down is an option. But I'd rather have MINI look at it and see if they can diagnose a fault of some kind. I've gotten quite used to this power!

 

Ben-Ja-Min,

The way they calculate octane is different between the US and UK. I remember that 99 octane is midgrade and 104 Octane is premium there but am not sure. They do not use the (R+M)/2 method we use in the US.

I always associated TESCO with being a grocery store sort of like Stop and Shop with a gas pump.

Nothing to lose to change your gas station and gas grade to see if that helps.

 

95 is the mid grade fuel here with 99 being premium. I might change up my fuel supply to see if that has any effect.

 

That could be a very bad idea if it's the tune causing the problem.

can you say bye bye warranty?

 

I live in Texas so cold weather is not a factor. Actually, the problems I am experiencing seem to happen in the hot weather. My 2006 Cooper S started having problems a year ago with misfiring and the engine & DSC light coming on while at highway speed. It went to the dealer, they cleaned the fuel injectors and said it was "bad gas". We have always used premium grade gas but to heed the dealers warnings for the past year we having only been putting Chevron, Exxon and Shell premium gas in the Mini. Less than 2 week ago, the engine & DSL lights came on with the car misfiring. After restarting the car, the DSL light went off for awhile but came back on but the misfiring stopped. The next day, the engine light was not lit either but we took it to the dealer (100 miles away) anyway and of course they found nothing wrong. They suggested having the fuel injectors cleaned for $200 and not to use "bad gas". We tried to tell them that we had been using only major brand premium fuels for the past year. So they did the scheduled maintenance and we were on our way... for a week. All the same problems are back. Not sure what to do at this point. Anyone else have the same problem, or more importantly, any advice? I have read of similar problems on other forums... is it really "bad gas", an engineering problem or both?