Was reading this thread

https://www.northamericanmotoring.co...ad.php?t=39082

and there are some posts about the bypass valve not actually closing completely. Anyone else have problems with this, as it is the first time I have heard about it.







As you can see there is a small leak past the butterfly valve.

Oh and pics are from bomboasy

 

how do you think that the engine idle's?

 

Thats not the throttle plate, its the bypass

 

Having installed the Ryephix2 bypass valve spring, I had a chance to check the butterfly in my bypass valve and noticed that it, too, was not adjusted to completely close during boost. However, mine was not as bad as bomboasy's was. I just needed to to adjust the set screw that provides the detent position for the butterfly when closed. Bomboasy's required that adjustment AND a realignment of the butterfly plate on the pivot.

When open, the bypass valve (as its name would imply) allows the air entering the engine's intake to bypass the supercharger. Obviously, this reduces power due to the drop in psi boost, but it increases gas mileage. When you are full on the throttle, the bypass valve closes to allow maximum boost to be attained by the supercharger, but whan you let off the throttle (when boost isn't required) the bypass valve opens to allow maximum gas mileage to be attained. It's kind of a cool setup, balancing between power and fuel efficiency!

The problem arises when the bypass valve shuts (max boost) but not quite all the way...you are loosing boost "potential". This was the case with bomboasy's and my bypass valve.

[Incidently, a problem in the software used for the vacuum control of the bypass valve's opening and closing is the actual cause of the "Yo-Yo". Installing Ryephile's bypass valve spring (Ryephix2) dampens the software-generated bypass valve oscillation and masks the yo-yo effect.]

The bypass valve supplier to MINI probably adjusts the butterfly's alignment and closing to within a tolerance range (hopefully). And, with statistically-based quality controls, probably meets MINIs dictated specifications. But that does not mean that every bypass valve is checked so you may get one that is really out of spec. I think bomboasy's was waaay out of spec (one would hope!) but it was not caught by QC efforts. Mine was closer to spec and perhaps within the tolerance range, but it still wasn't right!

The bottom line is that you will want all the boost the Tritec engine can make. It makes no sense to loose boost to a poorly adjusted bypass valve but spend gobs of money on other mods. However, bear in mind that getting to and removing the bypass valve is rather difficult and should be done only if you consider yourself a competent mechanic and have had experience doing this sort of work.

I was extremely careful and worked very slowly and deliberately. I still managed to put too much pressure on the plastic intake duct running from the throttle body to the SC intake port and snapped off a retaining tab.

FWIW,

Theo

 

I have an 02, and it needed stop and butterful ajustment. My photos of before an after are in the thread as well....

https://www.northamericanmotoring.co...att#post440757

I had light all the way around the butterfly, and it wasn't centered either. The difference in light was huge, but no dyno numbers....

Matt

 

The bypass valve's operation is not controlled by software. It's a simple vacuum diaphragm that opens and closes the valve.

 

Not really worried about dyno numbers, but it makes sense that if your bypass is always open you will lose boost. And since increased boost is good for power losing it must be bad.

Well if I get to a point where I mess around in that area of my enigine I will defenitely check out what my bypass valve is doing.

 

I understand the opening of the valve is vacuum operated, but it is the generation/regulation of the vacuum that was in question.

My understanding from speaking with Ryan Malcolm and by reading the yo-yo thread was that a sensor and PID controller (whatever they are) played a role in exacerbating the unstable vacuum levels due an inadequacy of the dampening algorithms in the controller's sofware. This created "oscillating" vacuum levels to the bypass valve.

Please set me straight, Andy. Are you saying that Ryan was off the mark with his assessment of the root cause?

Thanks

Theo

 

regalic,
Good idea. This issue with the manufacturing of the Bypass Valve should have its own thread. I should had started one for this subject, glad you did. The fact that some of the MINI S out there have Bypass Valves that do not close fully because the manufacturer is providing MINI with, in my eyes, faulty samples is a shame. Shame on MINI for not checking them before installation and shame on the manufacturer for not checking before shipping them to MINI. This is at the center of why we have MINI S vs a MINI. How can you trust any numbers between one MINI S and another, if you do not know how well each one can keep its Boost? Why bother to add expensive aftermarket parts if your MINI S is losing power at one of its most critical parts. I really like the comment from lotus87 "how do you think that the engine idle's?" It shows the trust that we have on MINI, to build this important part properly. Who would had imagine that that picture would be from the BYPASS VALVE. .


Bomboasy

 

if you examine the bypass valve, you will see it sources vacuum from the same area where it dumps boost...the runner between the blower intake and the throttle body. That will be a negative pressure area if the motor is turning and the throttle is closed. the throttle plate position is controlled by the foot pedal and the ECU (when you lift your foot, it doesn't slam shut, but is eased down by the ECU). so if something is modulating the throttle, you could also be modulating the runner pressure.

 

Did anyone notice a difference in power when the butterfly valve was properly adjusted?

 

Exactly as I understand it. So I thought there are algorithms in the ECU to dampen ("ease" or "smooth-out") the throttle plate's action when a "full throttle" or "no throttle" condition is communicated by the e-gas system. I thought it was this error in this ease-down/ease-up code that, through the throttle plate's inadequate dampening, cyclically modulated the vacuum pressure in at least a partial throttle state. This, in turn, created an oscillation in the pressure (vacuum) levels that actuate the bypass valve diaphram.

Thus, the genesis of the yo-yo is, ultimately, software-based.

Please correct me if I am wrong, as I am (obviously) not an expert in this system design but would like to make sure that I fully understand it.

Thanks,

Theo

 

I certainly didn't run any before and after dyno numbers, though that would be a terrific idea for someone to try!

Bomboasy's BPV was really way off so he might have a better feel for this. However, by my (prodigious) derrier-dyno, it felt that the 4500+ rpm range was a little stronger. Of course this could just be wishful "feeling" and I, personally, would disregard any informal feedback in favor of actual dyno numbers generated by the same dyno, on the same day, in the same environmental conditions, with the same car.

Theo

 

I've had an unwanted drivebility condition occure three times this week and I wonder if the bypass valve is at work here. (05 JCW)

Imagine entering a highway from a ramp and nailing the throttle as you move to the outside lane. Imagine too if a slower driver suddenly decided to occupy the same lane and you had to close the throttle a nano second after applying WOP. The car jerked suddenly like the engine was shut off - no, I wasn't bouncing off the rev limiter - about 5,000 rpm. Very, very disconcerting.

If 'easing' the bypass valve closed is part of the ECU/vacuum system, could this valve cause the above events?

 

That sounds like your traction control kicked in for a sec...

 

Wow, you think? The run began in third gear...I suppose it's possible. I'll try to duplicate with the TC off. But, it happens when the throttle is closed abruptly after WOT. The feeling is as if the engine momentarily shuts off - a fraction of a second.

Thanks Phobol


Ciao,

Michael

 

--->Koopah. I think what you meant to say was the underdamped PID controller facilitates the vacuum feedback resonance in the bypass valve. I knew what you were sayin though!


anyway Yes the Bypass Valve has a bad habit of requiring adjustment from the factory. I have yet to see one "out of the box" that didn't need fine-tuning to close fully.

 

It opens, the drive for opening decreases, it closes, the drive for opening increases, it opens.............

Matt

 

Almost considering just adjusting mine right after dealer pickup.

 

I stand corrected! Someday I'll really understand this stuff...but only for a day; seems that the synaptic connections aren't quite firing like they used to. Could the 60s have been responsible for this? I can't quite remember...

Now, where are my car keys?

Theo