hello i have a 2009 mini cooper s (r56) so i have a cnt down pipe(catless) i have stock exhuast second cat removed and put back togher with jmtc turbo and ecu tuning rough guess id say im pushing 250hp with all that i have done have 44mm turbo on it and my question is car has been perefect then all of sudden i lost boost and car was fine no big deal then as it progessded in days to come i i am currently running and having very very very poor preformance i have the torque app and i can wattch the car loose boost from 20 pounds - 18 - 15- to no boost i drive and smash it and runs some what good then i will loose boost and the sounds the car make from the turbo sounds like a woooooshing wosh wosh wosh wosh sounds when accelerating from 2 3 and 4th sorry if this is hard to understand and i exp[laine like a 4 year old just loosing boost at high and low rpms not hitting as hard no where near and as the woosh sounds does the noise i every 1 second or so i will loose power any ideas?

(i can loose boost at 2k rpm 5k rpm dosnt matter rpms car could sit all day and night and get in and boom smash it some pulls are good first 2 3 boom no boost some pullls are straight crap and some are pretty good just not full power ))

 

You have a leak in your intake tubing somewhere, that leak could be a loose pipe or even a bad blow off valve. You didn’t mention if you were using an aftermarket BOV or stock, but you need to do a smoke test to find your leak. You can DIY a smoke tester for real cheap (check YouTube), they come in handy for forced induction motors.

If this only only started happening after you deleted the cat in then downpipe, then you may have a “lack of back pressure” issue, this can be “tuned” out, but you need to find someone who knows what they are doing.

Good Luck.