ya it is 6 years old but only has 47,000 miles on it. I just ordered new IC boots from ALTA, see what those do (if anything). And im getting a compression test done on tuesday.

 

A bad bypass valve=no boost. Boost is what gives this thing +50 HP over the Cooper. Add to the fact that we have a lower CR and having no boost add all could theoretically result in less power than a Cooper. If you want to see if the bypass valve is bad you can zip-tie it shut (when the car is off it is shut) or you can pull the vacuum line off of it.

 

Well seeing as the before is the same as the tooned then it looks even more like BPV.

I know of tooners tooning cars with faulty bypass valves, its unfortunate that some haven't a basic mechanical understanding.

So if you havent someone local who can put a scan guage on and take a reading from the map sensor, then there is one thing you can try and that is get a cable tie zip tie it shut and try the car, but only try it once if you do feel the difference cut cable tie asap

Check the spark plugs to make sure there tight, thats another common one we see.

Check the belt to make sure that isn't slipping, one hole showing is good but check around to see if there is any build up of rubber.

If its an early blower (grey coat) the coating could of come off which would loose you boost.

Check intercooler for cracks.

Good Luck and it'll be well worth it when you find it because it'll be like having a new car

 

We usually take aftermarket ones off and put stock ones on

 

Is that only because the aftermarket ones are hard to put on?

 

Street tune's can actually be very beneficial. Especially when it comes to driveability tuning.

When you drive on the street, or even the track....do you drive stuck on WOT like on a dyno? No....

Street tunes fine tune driveability at all rev ranges. Ideally, you want a dyno tuned car and then take it out on the street for some final tweaking/tuning.

 

Zip tie the BPV closed and go for a drive and see how dramatic the increase is. If its notta then the BPV should be fine.

 

when u say to zip tie it, u mean zip tie the black plunger thing so its sealed to the diaphragm?

 

To the stop limiter, but you can also actuate the arm with your finger and feel for resistance, grittiness, or notchiness. If the spring is broken you will feel the click and hear the ping, it will also have little resistance and possibly fail to return to the stop.

 

well, i did notice that there was an extra 1/4" that the arm couldve gone back. If the arm supposed to be a TIGHT seal when the engine is off?

 

the arm should be all the way back against the stop when the car is off.

 

hmmm, ok, gonna try the zip tie test, ill let u guys know.

 

kk so after taking off the intake to get a better look i snapped a couple pics. The first pic is the BPV arm with the car OFF, the second pic is the BPV arm with the car ON. Let me know what you think!

 

Faulty BPV, replace with new OEM.

 

what makes ya think its faulty exactly??

 

The actuator arm failed to return the butterfly’s pivot cam to the stop limiter adjusting screw; 99% chance the spring is broken because early model BPVs have a brittle spring. I have also encountered the butterfly plate binding in the BPV bore, a cracked body, a torn diaphragm, and one that only needed a couple drops of oil, but yours is probably a broken spring.

 

cool, thanks! how much boost can be lost (realistically) from a BPV problem like this??

 

We had a stock one that made 110whp and then rose to 163whp, you'll have to take it back to the dyno and check the fueling, just use light throttle until you've been to the dyno.

 

Check out the IC boots Sneed"s Speed Shop sales! They are a multilayer rubber boot that can take some real abuse, working great on my car!!! Good price too...

 

Wow! thats reassuring!!!! was the BPV in the same condition as mine?

 

It was bent from a previous accident, the owner was happy with the new found power

 

was thinking.. how does this stock cooper s have 163whp? that means its rated 180bhp from the factory???

 

BMW likes to understate their powers... in case you have not noticed...

On my 335i, it's rated at 300bhp, but it dyno'd 270 to the wheels on a MD... so go figure...

 

i'd leave it alone till you get to dyno. then put the new one on that day . you will go lean if you run a new one without changing fuel trims . if it were me i'd have to do the aforementioned cause i have no self control and the hp would make me put my foot in it . question is .... do you trust yourself? well do ya?

 

A lot of it...