i have a Mini Cooper s r56 2013, i havent done anything to the car just a cat back and an intake. The problem is this(DOES NOT THROW CODE, just P0420,j ust a bad catalityc converter) , i start the car, it starts great no issues, idles perefctly, i ride for a while and after some time it does this weird fuel cut, a really jerky movement, only does it when light throtle or half, when its full throtle it never does this thing. after that when its idleing, the revs start to go to 1000 to 500 repeatedly, like it would if the HPFP was to go out and when i try to rev it, it feels as if it dosent respond good, i changed the spark plugs, and fuel filter and worked fine for a while, after that it startes the issue again, wnt to my mechanic, changed the spark plugs again, apparently bosch arent so good for mini, and after a while it started to do everything again. But this time, SOMETIMES when im low rpm and go full throtle just so the car dosent start to jerk, the blow off does a whistle noise instead of the pshhh it did.

I think it could be
-Coils
-HPFP
-In tank fuel pump
-vacuum leak?

Hoping its nothing too serious :0

 

Have you checked your diverter valve? If it’s making noises during the issue, it could be related. My gut wants to say MAF sensor. BUT... If you’re not using a BMW/Mini specific code reader, go get one. After the first diagnosis, it pretty much pays for itself compared to going to the dealer. Generic OBD readers will only pull the general codes that might be stored in the ECU.

 

I haven't checked the diverter valve, never had that happened before, but i have an Ultragauge, i dont know if its good enough to read those codes, and when i went to my mini mechanic, the reader didnt give him any code. But today the issue starte again, the revs started fluctuating and i checked any codes it had P0300 P0301 P0302 stored, and de fuel rail pressure was going crazy was going from 1200 to 2100, then it stopped fluctuating and the fuel rail psi was again back at 1000, so i think i can rule out Fuel pumps? havent checked MAF or cleaned it either.

 

An UltraGauge will not read the BMW/Mini codes. You need something like the Schwaben or Foxwell scanners.

 

i went to my mini/bmw mechanic, and he scanned it. He told me the car wasnt giving any codes, other than P0420, but thats the cat. And when it did the misfire and the fluctuating idle it didnt give a code either. this week when it started to do the issue the car gave this codes with my ultragauge ia have: P0300 P0301 P0301, so it is a misfire but dont know the issue, dont think is HPFP because when the rpms start tu go up and down the fuel rail pressure gets to about 1500 to 2000 when idle and when it stops it stays at 1000 idle.

 

Apparently the issue is much more constant when the tank is lower than full, and when its full it either does not do it or its less aggresive the stuttering.

 

Hi Just wondering if you ever discovered what the problem was as my 2009 R56 Cooper S has same problem.

fine when fuel tank is full but when I get to a 1/3rd tank it bogs down when i touch the accelerator or going around a corner weirdly.

have had High Pressure fuel pump changed and done coil packs along with sparks too.