Ever since I picked up my 03' MCS last week, it just seemed to me like it has lacked power. After doing some reading, it sounds like they have notorious problems with the stock bypass valves...so I thought I would check my BPV out.

So I found it under the right hand side of the intercooler......and I noticed that when I pushed the actuator in all the way and then let go of it, the spring return is not pushing the valve all the way back against the stop. It's a little hard to tell from the picture...but there is about a 1/16" gap between the stop screw and the lever arm. I can force it closed, but it won't close on it's own with just the pressure from the spring.

I'm assuming that this means that I have a bad BPV and it needs to be replaced? Can I just replace the spring? Why else would it not close all the way? Maybe that's why the car feels like such a dog.....it's bleeding off all of that boost!

What do you guys think...bad BPV??

Thanks!

 

Yes broken/tired old spring. It should snap back to return stop.

Jeremy

 

Anyone know where I can just get a new spring at? Would some place like Ace Hardware have one? Anyone know what kind of tension I need?

 

Go oem...
Starting in 2005 mini made the spring a bit stronger...
Detroit tuned sells the oem bypass valve with a stiffer yet spring...
some like the feel...some don't....it can make it harder to drive smoothly....but boost comes on quicker.

 

Has anyone ever went out and tried to find just a replacement spring for the stock BPV? If a weak/broken spring is such a common problem…why doesn’t anyone just sell the spring? I’ve searched the site from top to bottom and I haven’t found any info on just replacing the spring. Has anyone pulled a stock (or DT) BPV apart and gone to Ace Hardware or any other hardware store and tried to match up the spring? Sure would be cheaper than spending $100+ on a new BPV. Any info on just replacing the springs would really help me out!

 

If someone has a good spring, it's easy enough to measure it. Then go to a spring manufacturer like Lee or Century or SPEC and check their stocked springs. Likely something would be nearly perfect. You'll not find much at a hardware store.

 

Well...I wired the bypass valve shut just to see how much boost my weak bypass valve was actually letting by since it wasn't closing all the way.

WOW!!!.......it was like the thing instantly gained 50hp!!

I've only had the car a few weeks, and I been disappointed by the power...and even more so since it's a JCW MCS. It was sluggish, and didn't really have much power at all...and under 3000rpms it was a total dog.

With the bypass valve wired shut, it was crazy how much more power the motor has. Torque steer was trying to jerk the wheel out of my hand in 1st gear, and 2ns wasn't much better. I'm VERY happy with the power now......now my only question now is if I should go with the VGS mod and leave the bad spring in the stock BPV....or just spend the money on a DT BVP and replace it.

I do lots of highway miles to and from work.....so not loosing a bunch of MPG at cruising speeds (70mph...3000rpms) is a big concern to me. What's the best option??

 

I don't know if anyone makes something like this for the valve, but it would be neat to be able, from the driver's seat, flip a switch or something and adjust the spring pressure on the bypass valve. Adjust the spring pressure lower and you get better mileage for long trips. And when you wanted to, you could dial in more spring pressure for more power.

Is there a problem if the valve is wired shut? Can too much boost occur at higher rpms?

 

I think the problem (someone correct me if I'm wrong) with keeping it wired close.....is the fact the instead of there being no load on the supercharger at lower rpms, it's under a load all the time. So the intercooler runs much hotter, and you end up putting more wear and tear on the supercharger.

 

I don't think it's the lower rpms that are the problem. Those are the RPM's where the valve would likely remain shut anyway. I think it would be a problem at the higher rpm's, though, beause that's where the bypass valve would normally open and blow off the extra pressure.

It would be interesting to design something for the valve, that in one setting, would duplicate the spring pressure of the stock spring and then, by flipping a lever or something, would soften the pressure so the valve would open earlier for better mileage.

Hmmm......

 

No....I think you have it backwards. When the car is idling, or the motor has a light load on it like cruising on the highway or down the street....the motor makes lots of vacuum, pulling the valve open. When you mash the gas, and as the throttle body starts to open more, the motor doesn't make as much vacuum.....allowing the spring in the BPV to close the valve fully...letting the supercharger develop boost. That's why the DT BPV develops boost faster than the stock BPV...because the spring is stiffer, overcoming the vacuum of the motor faster..closing the valve sooner.

You want the valve OPEN at low rpms and cruising rpms...it's more efficient, and you don't need that extra boost and load on the supercharger. With a heavy load on the motor..you get less vacuum, which closes the valve..and you get more boost, which is what you want.

 

I'm still experiencing a lack of boost down low. I thought it was my BPV as well. Boost up high comes on okay but down load it takes forever to get moving. I went out and check my spring like yours thinking I'd find the same. Nope, mine sprung back pretty darn good. Does this mean mine is good or could it still remain open a bit under boost?

I just don't know if it's the car or me. I've had a couple high hp cars before getting back into a MINI. Maybe I'm just used to lots of down low power and my MINI is completely normal...

 

You can run the car with the BPV wired shut but you really shouldn't do it for a prolonged length of time, not only will your fuel milage suffer but the ecu will start to make adaptations for it and other settings will starrt to be off, basiclly you're just asking for more problems.

Aa far as the spring goes, yes with the proper info you can find one, there are other posts on the subject but honestly, I've read most of your other posts and from what I can see, just buy the DT/BPV, you'll be getting the most out of that part and that seems to be what you're really after. (basiclly, buy it, you know it's right, and it's out of you mind.)

 

Well, I went ahead and ordered the DT BPV....hopefully that should fix everything.

As far as power down low goes....I know exactly what you mean. I'm used to small block chevys, LS1 Camaro's, GTOs....stuff like that. These mini's are only 1.6 liter motors....not much lower end power, and that's just normal from what I've read. They are never going to feel like a big cubic inch motor down low...because they aren't. You just have to wait for the boost to build, then they start to take off. Mine is pretty dead anywhere under 3000rpms (I think that's normal)....hopefully the DT BPV will help some of that, but I'm not expecting to much more low end grunt out of it, I'm expecting more boost on the top end.

 

Your description of how/why a bypass valve is on the car is right on....the computer must make an instant adjustment when it closes.....
Some cars had yo-yo issues.....mostly fixed by software at this time...
A few things conspire to make lowed tq kinda weak besides the displacement...

One thing, very noticeable during the summer is heat soak from the lack of airflow/IC placement..tends to mostly go way in the cooler months.
pulley size is a true compermise to keep high rpm performance.....limited by the max desgin rpm of the sc, its effecency curve, and heat output....a pulley helps down low..tons actually, while slightly limiting top end performance.
The pistons on the r53 are pretty low compression, even in comparison to the r50, so till the car is onboost, performance is kinda weak....but the compression ratio was needed to keep detonation/ping in check on hot days/and with lower octane fuels.....
If you live in an area that has 93 octane fuel, the lag is not as bad...still apparent, but less noticeable than with even 91 in my experace...(e-10 and the higher fuel volumes needed to be pumped/flowed has been debated too...the stock injectors on an S are pretty much at max duty cycle..the reason why 2005+ jcw cars got slightly bigger injectors standard...they were the limiting factor..and the higher flow rates demands by fuel with ethonlol fuels to get thea same btu's only seems to make this more apparent).

 

Ah....I didn't fully understand how it works. Makes sense now.

Who makes this DT BPV?

 

DT = Detroit Tuned.

 

Well, I finally got the new DT BPV installed. It was actually pretty simple....took about an hour and a half to complete the job. The car runs so much better now.....it actually has power when you get on the gas now! According to my boost gauge, I'm getting around 12psi at WOT .....I'm assuming that's about right since it's a JCW car with the 11% JCW pulley on it. It runs great now!! I was thinking about getting the 17% pulley for it, but now that it's running good...I think I'll just leave it for awhile.

 

Good to hear.

(BTW change the 'JT' to 'DT' in your sig. )

 

How hard/easy was the actual install? Any walk through input? I am gonna have to give it a go and so far, I am completely blind going into it.

 

It was actually not that bad...just takes a little time. DT gives you pretty good instructions for installing their BPV. Just follow them one page at a time, and it's pretty easy.

On a side note...for some reason now after the new BPV install, I'm getting a flickering low oil pressure light. The oil level is fine, and everythng else checks out. I'm guessing that it's some kind of wiring problem....does anyone know if there are any wires or connectors around the BPV that would have anything to do with the low oil pressure light? It will come on for a second, then go off. If I give it some gas...it will come on, if I let off the gas...it goes off. If I hit a bump in the road...it will flicker on. It's driving me nuts...and I'm not going to drive it until I figure out what's going on.