*My issue has been fully solved, go down to post #20 for info.*

So I've had this issue for awhile now, every since I went and put the bigger turbo and tune on the car. The car was totally fine before putting either of those on as well. When ever I floor the car at or around 3k rpm in 3rd, the car will spool up and once it gets over 15psi the car starts having a hissy fit and the boost starts to fluctuate. But once I'm over 5.5k rpm the car will sometimes smooth out and hit 22psi. But if I rev it out to around 5k rpm in 3rd then hit it, it will fluctuate a little then hit 22si and pull nice and strong. Then when I shift into 4th the boost will then drop all the way down to 16-18psi and fluctuate around there, then once I'm over like 6k rpm it will go and hit 22psi. So far I've replaced the pressure converter that didn't help the issue. Then went and bought the GFB DV+ since I read that maybe the DV was being forced open under boost, but the it didn't help the issue either. I've also replaced the vacuum lines for the wastegate/pressure converter, that also didn't help. I also just replaced the air temp/pressure sensor and that also didn't help as well. The next thing I'm going to replace is the MAP sensor just to see. I've also adjusted the wastegate to the point where I don't think its causing the issue, but I don't know anymore. I'll try just about anything at this point.

Here's one video of it happening, but this is one of the times it wasn't doing it as bad. Video 1 https://www.youtube.com/watch?v=IezM...ature=youtu.be
Here's another video of it, if you listen closely it sounds as if its dumping a little boost or some weird noise that goes along with the fluctuation. Video 2 https://www.youtube.com/watch?v=kxbJ...ature=youtu.be
I also attached some logs, the torque app doesn't refresh all that fast to record the sensors but its something to show what it's doing.

 

Are you sure you don’t have a boost leak somewhere? What tune do you have? Anything else modded or altered in the turbo system? The DV+ is a pretty solid unit, so I don’t think that’s the problem, especially since it was doing it with the factory diverter too.
lastly are you getting any codes? And what are your plans for the old pressure converter? Heh heh.... that last one is totally selfish!

 

I had to use some headphones to get a good listen. In the second (daytime) video, it doesn’t sound like the diverter opening and closing or anything to me...I could be wrong..... but I definitely hear the fluctuations that you are talking about. Just offhand, I’m not sure I can give you anything you haven’t already thought of. But I am following with interest. Let us know how it goes and what you find out

 

I have a little update about this issue. It seems when I'm in boost (1psi or more) then floor the car, the boost will fluctuate bad, like in video 2. But if I'm out of boost and in vacuum then floor the car, it won't have a hissy fit when getting into boost. It still does fluctuate like in video 1 when in 3rd gear, but when shifting into 4th it still drops down to 16-18psi then rises to 22-23psi right near redline. Also did some pulls in 2nd gear and the boost doesn't fluctuate at all, it just holds steady at 22psi. And that's flooring the car when its in vacuum, not rolling into the throttle. I also replaced the map sensor and didn't make a difference with the boost fluctuation, but the torque app seems more accurate and close to what my boost gauge is reading. Next thing to check the vacuum pump and see if its in spec.

 

have you adjusted the wastegate? mine never was when the JCW turbo was installed, and boost was retarded. the nut was at about 10 turns, and i was overboosting and had weird boost sounds, maybe like yours.?
i am close to finding the right adjustment though, but i am also at the max i think i should go with adjusting the waste gate arm nut, 16 turns of the nut,
i am about to buy a boost valve to regulate the wastegate actuator and see what happens.
not sure i hear what you are talking about though, i cant tell if its wind noise on the Mic or engine weirdness.

 

I got around to testing the vacuum pump to see if it was in spec per pelican parts How To guide for it. It was pulling 29 inHg when I tested it and anything below 25 inHg is out of spec, which means the vacuum pump is fine. So I then decided to take off the wastegate actuator that came with the S42 turbo and put on the OEM one I had from the stock turbo. I did some pulls in 3rd and its still doing the fluctuation when getting into boost then flooring the car, but just punching the throttle when its in vacuum it spools up fine and hits 22 psi then falls down to 20-21 psi then climbs back up once its over 5500 rpm. I also did a 2nd-4th gear pull, and when hitting it in second gear it peaks and holds at 22 psi then shifting into 3rd it hits 18 psi then stays there until around 5500-5700 rpm then just instantly climbs and peaks at 22 psi and does the same thing in 4th gear. Its definitely better than it was with the OEM wastegate actuator. Now I'm just going to adjust the actuator to the OEM length and see what happens.

 

that is so much near identical to me its not even funny man...i would add maybe 1psi of boost to your numbers for me though but everything else is the same.
what is fact though is that you cant punch the larger turbos without having those RPM's up though, the system just isnt ready for that much boost. though 4000-5500rpm is plenty ready

what does sport mode do for you compared to normal?
normal for me is pretty straight forward and good. no jitter, no turbo flutter, seems solid, little to no overboost, infact, she hits 21psi and pretty much stops
sport mode though goes pretty spastic on me as it wants to really hit the boost and spooling and be jittery unless my RPM's are up.
the whole point of the system is to get you to max boost, and as fast as it can, but without the RPM's behind it, it cant, or will jitter, or flutter.
flutter isnt bad, dont let anyone fool you, so long as you dont sit there and flutter spooling and winding down, every single time you boost.
once in a while isnt bad.
jitter though, that confuses me and i dont know what it means.
jitter = boost goes 21 up to 23 and just bounces in that range until i shift. it will do it in lower psi, but rarely.

 

I'm back with another update. I adjusted the wastegate to 152mm as per the picture I posted my last comment. Then trying what cyberlunacy said, which was to try the car in normal mode (non-sport mode) to see what happens. And in normal mode, in 3rd gear, the car peaks at 22 psi and will dip down really quickly to 20-21 psi for a couple hundred rpm then goes back up to 22 psi and holds until redline. 4th is some what the same, when shifting from 3rd into 4th the boost drops down then comes back up to 18ish psi then holds there until 5700 rpm then starts to climb up to 22 psi. Now when starting in 2nd gear in normal mode, it goes and hits 22 psi absolutely fine no hiccups nothing, then when shifting into 3rd it goes and peaks at 20 psi then falls down to 16 psi then slowly climbs back up to 20 psi once its over 6000 rpm. Then shifting into 4th it does damn near the same thing, but only peaks at 18 and falls to 16-17 psi and holds there, then climbs up to 20 after 6000 rpm. Now trying it in sport mode, in 3rd gear, it does the same exact thing cyber says his is doing. Which is fluctuating/jittery boost and it just bounces between 21-23.

Edit: Here's some new videos of it happening.

 

ok man i cant stand having the same issue as someone else and not trying to help even when my Mini knowledge is limited.

i may have just fixed mine, so far so good.

i have the K&N Oil based Typhoon filter... i put the stock air box back on with the higher than normal flow Mann filter. high enough i can blow through it and feel plenty of air on my hand.
the K&N filter i have to use my compressor and i still cant feel alot of air.

i put the stock airbox back on and most of my boost issues are gone, my car idles properly again, and i can mash on it at 3500rpm and it hits 21psi and sits there. no bouncing, nothing.
shifting and boost seems to be more controlled now too.

not sure if you have the foam or K&N filter option on the DDMWorks Intake but i would be looking at putting the stock air box and intake back in for an afternoon of driving and see what happens.
the K&N filter is now on my "do not ever buy again" list unless its a dry filter and i can test it for air flow at a parts store.

 

I have the dry filter from afe that WayMotorWorks sells with the intake. I've had the same filter on the car since I installed the intake, which was over 3 years ago. I just bought a new filter from WMW so I'll see if that fixes the issue. Sadly I don't have the other half of the stock intake so I can't put that back on, unless I go and buy a whole used unit from ebay. I have washed the filter before since afe says you can, but after looking on WMW listing for the filter they say, "This is a great spare or replacement filter for your DDM intake" so maybe you can't. IDK.

 

After putting the new filter on the car and going and doing some 3rd gear pulls, the boost fluctuation seems to be gone when it's in non-sport and sport mode. It still only hits 20 psi when you floor it, then once its over 5500-5700rpm it then climbs up to 22 psi and holds steady until I shift. Then when I get into 4th it doesn't drop all the way down to 16 psi anymore, it goes up to 19-20 psi then sits there until 6k then goes up to 22 psi.

 

Have you noticed any degraded performance?
mine seems more refined, tighter, not so willing to just dump full boost. It’s like the car now demands that you actually get into it, where prior, 1/2 throttle was full boost, and too early.
I wonder if something has changed in the stage 3 where people aren’t chiming in about this already., also wonder what filters they are using?
or its atmospheric conditions making the car run differently, though the tune and ecu should be accommodating for this.

i cleaned the k/n filter so that now its a dry filter and the boost is more controlled, but not nearly as good as the Wix (i thought it was Mann) filter which just from a mouth blowing through it, and air compressor test, allow more air to flow.
so i have come to the conclusion the k/n cone filter cant produce the air flow the engine needs. It’s too restrictive.

i also bought the MiniMania foam filter which had i read the ONE line of text in the entire webpage of the product i would have noticed it is an oil based filter, and i would have never bought it. Friggin thing was just caked with oil when i got it.
i cleaned it with gas and let it dry, and did some pulls around town, and its similar to the Wix stock filter but would need more testing to be certain.
but i would avoid this filter too, i still dont think it offers enough air flow.

i would have to see some logs of pulls using a high flow stock style filter vs. something like the minimania foam to believe its better. But wet with oil.. no way,

oil filters are super restrictive and just from that standpoint alone, let alone the oil getting on the MAF sensor, shouldn’t be used, i really truly wish i had tested this months ago, but now that i know, i will only look for a much higher flow stock filter.
though i miss, already, the sound of the turbo recirculating, but oh well, its a sound, not a need.
and as many have said the N18’s can be a little weird when blow off is to atmosphere, which i still find to be a little odd given the minor amount of air recirculating but oh well..

ITG makes a very good foam cone filter if you wanted to import from England (i cant find any USA sellers)

 

I did notice I needed a little more throttle to get it to spool up and get into boost with the new filter. It never hit full boost on 1/2 throttle for me, but 3/4 throttle would push it damn near 20 psi though.

Have you done any 2nd gear pulls with the new filter you put in? I did a couple 2nd gear pulls last night and the car moves out now, it hits 22psi and just holds there. It feels like a totally different car in 2nd gear now. It was the first time I've felt the car was actually producing the 250-260whp figure that's being thrown around with this tune/turbo combo. But once I threw it into 3rd it just falls on its face and only hits 16 psi then climbs to 20 psi before I shift into 4th. I just don't understand why it will hit 22 psi and hold steady in 2nd gear but just dies in 3rd and 4th gear. Even just flooring it in 3rd it will hit 20-21psi but it feels nothing like it does in 2nd.

 

Today for the first time I experienced what you have been describing second gear cranks then 3rd gear just pukes to about 15psi and it was really lacking power then shot up to 21psi - this was the stock Wix filter
got home put in the dry k&n typhoon cone filter and went on a dodge the cops run lol did good.
but also there were some weird spooling fluctuations, hit max boost a few times and it started bouncing again on the boost guage and you could hear it sounding fluttery without making the actual turbo flutter sound.
now whats your weather like? Here today in iowa its was awefully warm though not unbearable so i wonder if heat is coming into play?

but i am starting to think its a vacuum leak somewhere or VVT solenoid (causing rough idle dont know what it does for boost)
but even a small vacuum leak will cause craziness
even so much as my Wagner cloan large intercooler not pushing enough air.
i got half a mind to find a pure dry cone that has very little restriction and try it
wish i could put a filter right on the turbo and bypass MAF that would tell my if if MAF or a lack of airflow

 

Its mid 90's down here during the day, but low 80's once the sun goes down. I'm going to pull my intake manifold off and see how much carbon build up there is on the valves. Then go from there I guess.

 

How goes the testing?
im about at my wits end with it being intake related other than one intake restricting more than the other.
i just cant tell where the fluctuations are coming from.
i assume the boost hitting 15lbs then jumping to 21lbs and holding is an air flow thing.
but why with the k&n filter does it bounce at max boost, is it trying to boost more and the wastegate is bouncing to compensate?
is it not intake at all but vacuum? But wouldn’t that be all the time no matter what?
Is it something else i cant even imagine because of the bmw engine and the way it works?

 

Welp after a couple months of digging around and talking to Trigger2011 and Cyber the boost fluctuation and inconsistent boost is now no more. I bought both the tune and turbo June 2018 and have had these issues ever since putting them both on the car. I ended up having to take the turbo back off and replaced the turbine housing with the stock turbine housing I still had laying around. Put the wastegate preload to 152mm like in the picture in comment #6 and now hit 16 psi in gears 1-5 with out an issue. Will start adding preload to the wastegate this weekend until I see 21psi and then leave it be.

Also, the only other thing I replaced before taking off the turbo was the fuel filter, that seemed to help with more consistent pops and bangs but other than that it didn't do anything. Also replaced it since I'm at 80k miles. If you're also wondering how I tracked it down to the turbine housing that was all Trigger2011. I ended up sending him logs everything checked out fine except for the boost issues. He ended up telling me hes had two other people with JMTC turbos have the same issue, where the turbine housing that came on the turbo has tolerance issues and was causing boost issues. Low and behold I end having the same damn issue, what a joke.

Here's a 4th to 5th gear pull with the stock borgwarner turbine housing. https://datazap.me/u/neonled/log-157...9&solo=3-4-8-9
Here's a 4th gear pull with the housing that came on the S42 turbo. https://datazap.me/u/neonled/log-157...9&zoom=160-433 Keep in mind both logs have the wastegate set at 152mm (6 inches) for preload.

 

that's really awesome that you finally found it! I cant wait to hear your comments after you solidify the boost.

what does that mean for the money you spent on a bad turbo? are you s.o.l. ? seems like there should be a warranty on it especially if you were in contact with the seller originally and possibly thru ought all this.
I think mine was about 14 1/2 turns I think, maybe it was 13 1/2 I forget. only had to adjust it twice one I counted the turns of the nut.

I just thread the nut all the way out to the end near the vacuum actuator, then mark with a sharpie on the nut and count 13 full turns then tighten the side on the other side and make a few runs and see what its like. and adjust more or less.

here is a hint about the turbo head shield... take a pair of tin snips or cutting wheel and cut the heatshield where the bolts go, so its not a hole anymore but an open U shape.. that way when you take it on an off, the bolts by the valve cover hold in place, and the ones below by the radiator, you can then tight up again to hold the bottom.
loosen them , take the top ones off and you can slide, somewhat easily the shield off. put it back on slide the bottom on, maneuver the top on and tighten them down.

 

Glad my input helped you get it sorted. It's unfortunate the maker of the turbo or the tuner wasn't able to help you get to the bottom of it sooner but I'd say you now have pretty clear evidence the original housing was at fault. Might be worth reaching out to the manufacturer again with new datalogs after you get it dialed back in.

 

After a long 2 years dealing with issues they are finally gone. I kept talking to Lou at Prototype-R after fixing the boost fluctuation. He was nice enough to send me his data logging software that he sends his clients when they buy a stage 3 or higher tune. From there we went down a rabbit hole to figure out what the hell was going on with the car. I logged the car on the jmtc turbo and the RPM "Stage 3" tune and found out the JMTC turbo was maxed out at 1.3 bar (18psi). The wastegate duty cycle was pegged at 91% which is uhhh ya, trash. As for the RPM tune it was only requesting 1.4 bar (20psi) but yet everyone that runs RPM is told to tighten the wastegate until you see 22psi hmmm.

In the picture below is a 3rd gear log from the RPM tune and JMTC turbo. I want to note that the boost is read in atmospheric bar, so move the decimal to the left twice and minus it by 1 to get the right boost. Orange line is RPM, Redish line is wastegate duty cycle, Blue line is requested boost, Yellow line is actual boost. As you can see the wastegate is pegged and the boost is slowly falling off in the top end. Which a "bigger" turbo shouldn't be doing. The boost falling off is one of the reasons why you upgrade the turbo.


After sending more logs to Lou so he could look over them and see if he could do anything performance wise and clean the tune up. He ended up saying he could get a little more power out of it but the turbo was maxed out and I would have to get ANOTHER TURBO if I wanted even more power out of it. After him saying that he said I could go ahead and buy the stage 3 tune from him. He didn't want me to waste more money if he couldn't fix it or improve on what was already done. So I ended up getting buying his Stage 3 tune and Stage X handheld device. The picture below is the file from him and is another 3rd gear pull. He ended up having to requesting 1.6 bar (23psi) to try and get the boost to hold up top but it was still falling off a little. He did manage to pick up torque in 2nd gear from what I could tell on the butt dyno and pulled decent up to 90ish mph.
Orange line is RPM, Redish line is wastegate duty cycle, Blue line is requested boost, Yellow line is actual boost.


When I purchased the Stage 3 tune from him I also bought the Stage X hand held device. Its like a mini touch screen tablet which can hold the stock file plus 5 tunes, or custom maps if you're Stage 3 or higher. When I got the RPM tune the pops and bangs were not there at all. I would let off the throttle and only get like one bang or pop around 3k rpm. I ended up sending the ECU back to get pops and bangs increased and after getting the ecu back and it went from one pop at 3k rpm to 2 or 3 pops at 3k rpm, WOW. Now the nice thing with custom tuning you can pretty much do what ever you want. When Lou sent me the tune he had his version of the pre-LCI minis pops and bangs. And oh boy are they aggressive and loud. When I mean loud, you can literately feel them in the pedals and seat. I ended up asking him to turn them down just a tad. He went and sent me a new file that contained 4 different pop and bang files that got more extreme with each file. I ended up settling with #3 since they were more of a pop and burble from 2k rpm to 3.5k rpm then progressively got louder as the rpms went up.

As we were messing with the pops and bangs I asked about turbos. Long story short I got my hands on an actual upgraded turbo that has KO4 wheels made from a band new Borg Warner OEM turbo. Once I put the new turbo on he sent me a new test file to data log on. He kept sending tunes and I kept sending logs back. Ended up getting to revision 10, and ran into an issue where the ECU would pull boost out the car when I would shift gears. But it wouldn't do it if I just got on it in like 3rd or 4th gear, it only happened when I shifted. As a last ditch effort he team viewered into my laptop and flashed the car back to stock with BWM Tools. Which didn't work sadly, at least I don't think it worked. So we kept trying different things and turning off safety features that he has in place to see if any of those were affecting it. They weren't. He ended up seeing that the MAF was reading higher than normal and sent me a Mafless style tune. He didn't zero out the maf tables in the tune since they were still recording in the datalogs, but the ecu just wouldn't react to what the maf was saying. And sure enough it worked, the car didn't pull boost out when shifting.

Picture below is comparing the boost falling off in 4th gear to the mafless file that held it. It still fell off since he pulled boost out of it just to see if the mafless would work. This is on 1.3 bar (18psi) as well. He limits boost in 2nd gear to help with traction which is why its way off the target. Blue line is target, Yellow is actual boost.


With the car now actually holding boost we ending up running into yet another issue -_-. The iats were getting up to 55c (131f) by the time I was at 6000rpms in 4th gear. At 60c (140f) the ECU will start to pull timing to save its self. So I did the sane thing and spent more money and bought the Aquamist HFS4 kit to run water meth. Once I got it on the car we dialed in the 1.3 bar map (18.8psi) and the 1.4 bar map (20.3psi) so I can run them without meth if I wanted to. Then he sent me the big boy file, the 1.5 bar map (21.7psi) with some more timing in it to take advantage of the meth. And oh boy did that wake the car up. I thought we were done there, but he then goes and sends me another 1.5 bar file with the max timing he will run on stock Cooper S pistons. The car is an absolute animal now. It pulls and pulls and just keeps pulling. Its actually insane. I went from not being able to spin 1st gear on RPM, to spinning 2nd gear.

Picture below is the final version of the meth map. Red line is wastegate duty cycle, Green line is intake temps in Celsius, Blue line is boost requested, Yellow line is boost actual. As you can see the wastegate is only at 83% pushing almost 22psi in the top of 4th gear. While the JMTC was max out at 91% at 18.8psi. You can also see the iats are really low considering I live in Florida with 90f ambient temps and 60%+ humidity. The meth doesn't work as well for cooling when the humidity is high.


Now onto the dragy data I got throughout this whole process. I didn't have the dragy when I was still on RPM but I did do a 40-60 on using the toque app but idk how accurate the torque app is since the data transfer rate is slow.
As for the data below all times are based off of 40-100mph. I didn't want to do 60-130 cause it took forever to get up to that speed on the jmtc turbo so I kept it to 40-100. The car dropped a whole 1.25 seconds off in 11 degree hotter weather and a 650ft higher DA. Then dropped 1.78 seconds off in 5 degree hotter weather and 440ft higher DA. When comparing both maps on the new turbo to the jmtc turbo. Once the temp decides to drop and the DA gets lower the time will also lower. I also want to do a 60-130 since I can actually use 5th gear now, since it would fall on its face when the jmtc turbo was on the car and couldn't keep up.


To end this all off, be careful of who you give you money to and make sure you aren't buying some POS china charger like I did. I know a lot of members on here run the JMTC turbos and seem to be fine. But the only reason I found out I had an issue in the first place was because of my boost gauge. As for the people that want to run a bigger turbo I highly recommend meth, yes its a lot of money, but the power you can push is nuts and it will also lower the egts so you dont burn an exhaust valve like some have. As for the tunes there is no reason to be spending $700+ on a canned tune when you're on a bigger turbo and meth or even on a build short block. Not every car is the same and will react differently. Find out if the company you contact does custom tuning cause there is no reason not to offer it and make sure they have legit data logging software, not the shitty torque app that records 2 times a second. As for the china charger I bought for $1100, heres a thread I posted on about it, as someone else had already made a post about their quality.

If you're wondering how much I've spent, its well over $4,000 just between the RPM tune, JMTC turbo, Stage X, and New turbo. Then another $1000 for the meth kit. That doesn't include labor either, I did everything myself so I save a couple grand there. Hopefully others can learn from my mistake and not blow their money on trash.

-Neon

 

Nice to see you got your car sorted out! I’m hoping to go stage 3 next spring, and Lou is top on my list of tuners.

 

I wish I had seen this sooner. I'm on my second turbo from a very similar source and am experiencing identical issues.

 

Sad to hear and see. Makes me wonder how many others have issues but don't actually know since they think its normal.

 

For real. What really gets me is that these turbos aren't exactly cheap. If I had bought a Chinese turbo from eBay or Amazon, this is what I'd expect. But a $1300 turbo from a reputable "tuner"? Hot garbage.