Guys,

As the title states. I'm having a boost flutter problem under partial throttle towards 5-10 psi. It only happens in partial throttle. I get 16 psi at WOT.

Did a smoke test and it didnt show any leaks. I replaced the BPV and the throttle body.

Need help...thanks.

 

These cars have a dead spot around 2500 RPM, is that what you're experiencing?

What is the condition of your belt?

Any codes present?

 

Kindoff a dead spot when accelerating. If you mean when I press on the pedal the car wont go until I press a little bit more, then yes. But, it is not a yoyo, the car does not jerk, but you can certainly feel it a little bit. I notice it in my boost gauge.

The belt is faily new, I installed it with a new belt tensioning unit about 10k ago. I do have a 15% pulley.

No codes are showing.

 

Things I've tested and ruled out:
- in HG is -15 at idle with A/C off and around -12 with A/C on
- Boost hits 15-16 PSI at WOT (15% supercharger pulley)
- Changed the BPV with new OEM one
- Checked for boost leaks in IC boots
- Checked my supercharger inlet tube and it seems to be sealing correctly
- Throttle body gasket replaced
-New MAP/TMAP sensors
-Used but in good condition Throttle Body
-Passed a smoke test under 5 psi.
- New Fuel pump and fuel filter

Things on the way that may or may not be:
-o2 Sensor
-Throttle pedal

 

I don't recommend you keep throwing parts at the car. If you don't have definitive proof of a failure point you'll only throw more money out the window than is needed.

If you are feeling a dead spot in the 2500-3k RPM area that is totally normal, some cars it is more prominent than others, and others will become worse with mods. It's all in the factory tune.

 

My car was tuned by RMW and it never did it before and after the tune with same parts. It always drove smooth and like a champ.


The parts I'm throwing in had to be done anyways some day and are OEM.


Just recently after I had my clutch changed. Believe me, I would've noticed beforehand, I know the car very well. And a clutch has nothing to do with a tune. I'm thinking while re-assembling, the shop might have might have damaged something unintentionally.


But the only things that are messed with while doing a clutch job, I have taken out of the list.

 

I don't know, sounds normal to me. My car flutters slightly at around 1/2 throttle and 3k RPM. I don't worry about it because it feels like the BPV on the supercharger is trying to decide whether or not to go into boost. There is just the right amount of air volume and pressure at that amount of throttle and RPMs to cause the spring to bounce back and forth between boost and no boost.

Correct me if I'm misinterpreting you, sounds like that's what's happening to you from what I'm reading.

 

I'll post a video this afternoon.


Sevin,


I know that pre-facelifts R53s had a softer spring in the BPV and that may be the cause, but mine is a 2006. I can feel the fluttering a bit at partial throttle at about 5-10 psi in any gear...there is a sweet spot in the accelerator pedal where I can get it to do it.




My throttle pedal feels a bit lazy though, kinda of a delayed input.

 

I think you are describing exactly what I described, but maybe I'm misinterpreting you again. It doesn't matter what gear you're in, so long as the volume and pressure through the BPV is just right. I can create it whenever I want just by playing with the throttle around 3k RPM.

The lazy throttle pedal is a function of the drive-by-wire system MINIs use. It's electronic, not direct linkage. Some people use a Sprint Booster, which essentially remaps the throttle to trick it into thinking you're pushing down harder than you are.

 

 

Doublepost

 

Sounds and looks like the BPV fluttering, I would start diagnostic with reviewing the BPV install.

 

Just for documentation purposes:


Things I've tested and ruled out:
- in HG is -15 at idle with A/C off and around -12 with A/C on
- Boost hits 15-16 PSI at WOT (15% supercharger pulley)
- Changed the BPV with new OEM one
- Checked for boost leaks in IC boots
- Checked my supercharger inlet tube and it seems to be sealing correctly (new SC inlet tube gasket)
- Throttle body gasket replaced
-New MAP/TMAP sensors
-Used but in good condition Throttle Body
-Passed a smoke test under 5 psi.
- New Fuel pump and fuel filter
-o2 Sensor, new
-Throttle pedal swap with my girls MCS
-Fuel pressure: ~40 idle, ~52 ignition on/car off, ~60 psi driving

Things left to do:
-Pressurize intake manifold with boost leak detector +5psi


Will do. It was doing it beforehand with the old BPV. I'll put the car in service mode go over things again. It has to be something between the supercharger inlet tube and the BPV. This is frustrating.


Thanks for your help!

 

If you are adamant about it not being a BPV problem start looking at belt drive components. Is your crank pulley coming apart? Is you belt the correct size? Is the SC pulley slipping on the SC shaft?

That kind of deviance wouldn't be caused by a small vacuum leak.

 

Well,

I went ahead put a new belt in. It had the correct belt on. The old one seemed to have been a bit stretched, but reality is that it did not fix the problem. I also have an ATI super damper pulley, verified and the bolt was tightened to spec. The belt tensioner I had replaced 10-15k ago, and I inspected it, it fine.

I exchanged the ignition coil from my girls MCS, just for ***** and giggles, the problem is still there.

I'll look at my spark plugs next, which I doubt are bad.

I totally agree with it not being a small boost leak.


I did the zip tie thing with the bpv, and it didn't seem to help with the acceleration any. However I did not feel or see any fluttering...I saw my AITs rise considerably, by like 80 degrees. Makes me think that the supercharger is spinning faster than it should? IDK


How would I know if my supercharger pulley is slipping on the SC shaft? I visually inspected and pulled on it and seemed to be well bolted.

 

If the car is building boost, charging the battery, not illuminating a battery light then chances are that the SC pulley is fine.

If the fluttering went away after zip tying the BPV closed then I would assume the BPVis the culprit. Did you replace it with a factory valve, our DT BPV gets rid of the yo-yo or fluttering you feel.

Detroit Tuned Bypass Valve

 

I replaced it with a brand new OEM. Weird that before the clutch being worked on, it never ever did that. :-/ Ohh well. I'll be ordering one soon.

 

Finally found my problem.

I was adamant about the BPV install, you were right.

I was like that because I took the car to a shop to get a smoke test. And they "didn't find anything". I'm thinking they just wanted a quick buck or something and replaced my fuel injector o-rings...which didn't make any sense.

I deviced my own "machine gun jubblie", and did a pressure test. I didn't see anything at first. I wasn't using soapy water though.


Today I decided to do the pressure test again at a higher psi and using soapy water at 10 psi. Result; found the damn leak.

The leak was on the hose that connects the BPV to the SC inlet tube. One of the clamps isn't clamping correctly.

Gonna replace the damn clamp with a hose screw clamp.

And this is why I really hate taking the car to a mechanic to get my car fixed.


Thanks for your input, much appreciated.....

BTW I ordered a DT BPV....don't know if I'll be using it.

 

98% of the time vacuum leaks or idle problems that "pop" up after BPV installs are the install.

I'd be interested to hear why you won't be using the valve, but we will be the first to say that it's not for everyone.

 

Have had the DT BPV installed since Raven had about 80K miles I think. Now at 228k plus and still works flawlessly. Nice to have that boost more readily available at the touch of the throttle.

 

We have many customers who have told us how they solved their throttle lag problem with the very simply installed Sprint Booster. Might be worth looking at.

http://new.minimania.com/Sprint_Boos...eviews_Part_II

http://new.minimania.com/SPRINT_BOOSTER___Why_it_works

Hope this helps!

Drive Hard. Drive Safe. Keep Grinning.

 

Thanks, but the car is tuned by RMW and there was no need for the sprint booster. I appreciate the offer though.

 

I'll give it a try when it gets here. I like the readily available boost, it'll be good for autoX.

BTW I'm having to replace the hole plastic inlet tube. The part that connects to the BPV is cracked in one of the plastic welds, veeery veeeery small crack. The guy who did my clutch must have messed it up somehow. Not going to epoxy it.

WHY IN THE WORLD did BMW decide to design that part like that, it's so freaking fragile. They could've done a solid piece from a mold? SMH!

Might as well throw it in. I was adamant about it because I though that the newer BPV already had a somewhat stiffer spring, compared to earlier models.

 

Here's my little one.

Can't wait to get it back on track.



That's my little one!

 

The 05-06 bypass valve is slightly stiffer but it still wears out. I replaced mine with another oem valve. The Detroit tuned is a preference part like he said, some like that slam you, boost feel, I prefer the more linear boost feel.