My question is, do I have any reason to change the vaccum location if I just installed a Detroit Tuned bypass valve? I figure I might was well do this while the IC is off, but I'm not sure it's really necessary on the DT BPV. Thoughts? It seems bomboasy has both.

 

No, if you have the Detroit Tuned BPV, don't make any changes. It's designed to correct the problems associated with the OEM design.

 

Thanks for the tip Dutch! My VGS mod sorta created a little yo-yo at low RPM, too.

I do agree with getting the Detroit Tuned BPV as the end all fix. Will have get one in the near future.

 

After posting I decided against the VGS and buttoned the car up last night. The yo-yo I had at low throttle is completely gone. My old BPV stays shut when just sitting there as well, so I don't really notice any more boost, but there's probably a little less leaking out now I'm sure.

 

there are lots and lots of causes of yo-yo. While the restriction method helps for some, it doesn't for others. The VGS helps some, not others. The DT bpv helps some, but not others. All affect throttle response a bit, so what works best for you may not give a driving experience that others like. So be carefull when one says "this is a fix for all", cause they never are!

Also, keep in mind that the TB position is controlled by a software feedback loop, and that this can oscillate as well, and can lead to yo-yo type behaviours. What makes it really complicated is that the purely mechanical by-pass valve operation couples to the TB control loop, so you have coupled feedback loops, and this can get to messy instabilities really fast. Just look at how many ECU updates it took Mini to really get it sorted out, and this was for most, but not all, cars!

What worked well for me and how I drive is I adjusted a stock BPV for good closure, and stretched the stock spring a bit, and run the VGS. I didn't like the light throttle modulation of the really stiff spring in the DT valve, but then again, this is purely personal taste and everyone may have different feelings as to what works well for them.

Also, if you do add some vacuum lines for whatever reason, make sure to use wire-ties to really hold them tight on the barbs. Remember, that some of the locations see boost as well, and not all vacuum lines will hold the boost. That's why MINI uses the lines that they do, and why they are such a pain to put on and off.

Matt

 

Thanks Doc for the post. It is important to keep in mind not everyone will benefit or like the VGS mod. And thanks for the pointers on the BPV plate and spring adjustments. I have not even gotten that far yet in trying them.

 

True, true. I am more or less happy with the VGS and a little cotton shoved in the vacuum line. I just know that I'm losing an as-yet-undetermined amount of boost to the poorly-adjusted throttle-stop screw (which is stuck in place with some rather strong thread-locking compound), and happened to snag a used DT BPV at a price I couldn't refuse. If I drag my feets a bit, I might get my vac/boost gauge installed (courtesy of some birthday $$$ to buy the gauge pod kit with--budgets *suck* ) *before* the BPV, so that I can watch the vacuum/boost needle and get a better idea of what's going on in the "black box"....

I suspected as much WRT the throttle position, but I haven't seen a good explanation yet of how this particular ECU controls stuff. I can feel a difference in throttle responsiveness after turning off the ASC, though--it's as if a layer of software lag is removed by turning that off.

From my experience with electronics, I know having two (or more) coupled feedback loops is inviting a degree of randomness into your world that can be rather maddening. Cotton in the line does a good job dampening any tendency toward oscillation caused by the VGS, so that you can reduce the number of variables to a manageable level, though....

I was planning to try that first (stretching the spring and adjusting the throttle-stop screw), but fell into this deal. It's my daily-driver, and we're not allowed to do work on cars where I live, so I have to arrange to go to a friend's place 20 miles away, then wait for the car to cool off before I can start work, and I have to limit it to stuff I can get done in part of a day.... Once I have the original part off, I will see if it can be adjusted to work properly and keep it as a spare.

C ya,
Dutch

 

you're on top of it.... Best of luck!

Matt

 

Well, so much for dragging my feet until I got my Vac/Boost gauge installed.... The time (and hassle-free space for doing mechanical work) needed to swap the bypass valve presented itself to me yesterday.

I now have more torque across the board and much improved throttle response, due to the DT unit improving over the stock one's weak spring and poor adjustment. I can also hear and feel the newfound grunt in the exhaust note (and seat-of-the-pants vibration) at lower RPMs. Nice.... Me likey!

Catalina Highway was a joy in 4th gear all the way up Mt. Lemmon to over 8000 ft. as my 'test drive'. This is going to make the car much more fun in the twisties, and make putting around town a bit easier, with earlier upshifts possible (if not probable ) due to all the newly-added torque.

Also, I have noticed that pretty much immediately upon pressing the accelerator down a bit, I can feel the valve closing, via the little "bump" in acceleration that it causes. Kinda gives "putting the hammer down" a literal translation into the driving experience....

Simply stretching the spring and properly adjusting the setscrew on a stock unit, in combination with the VGS, would yield similarly improved results over the stock part. Had I not stumbled on a used DT unit at a bargain price, I would have eventually found a JY around here with some MINIs in it, and gone that route....

Anyhoo, some pixs....

Before:

Note the amount of light you can see around the throttle plate at the point where the spring stops trying to close it. To quote Wile E. Coyote, "Yipes!"

After:

The DT unit's spring closes it all the way fairly firmly, so that actual vacuum is required to pull it open. It also has its stop adjusted so that the valve closes tight....

With VGS, and a setscrew adjustment, you can get yours that tight too. If you're more adventurous (or have a spare in case you break it trying to get it open), and want to stretch out the spring to make it close all the way without waiting for the boost to help it, you'll be rewarded with *much* improved low and mid RPM torque....

C ya,
Dutch

PS: the innards of the bypass valve:

 

Wow I am very late in to this thread. This looks like a great mod. I am suffering from the known yo yo problems and my car seems to bog greatly in first gear.

My question to Andy or anyone is, Will this mod work on a 2005 model I remember reading somewhere that 2005 is the redesigned Bypass Valve. Either way my car was manufactured in 8/04. Will this mod work for me?

 

Well, for the price of a bit of vacuum hose and a vacuum tee, and a little of your time, you can try the VGS. If your car's got symptoms like that, you need *some* sort of fix....

Check the bypass valve to see if it's closing all the way. If you look down into the darkness under the driver's side of the intercooler "horn", you'll see it. There's a set-screw, and the little stopper plate on the end of its throttle shaft. If it's not or if when you push the plate away from the set-screw, it doesn't come back to rest against the set-screw, then your bypass valve's spring is weak or broken. VGS can help you until you have the $$ to put a new bypass valve there.

There's a (slightly blurry--sorry, camera phone...) pic on one of my earlier posts of the bypass valve's set-screw, if you are not quite sure what you're looking for.

HTH!

C ya,
Dutch

 

I Must Say WOW! I just finished the mod and can say the car runs totally different. First gear is great and does not bog like it used to off the line. Before I felt I had to burn clutch to get the car off the line without bogging but now it feels as if the car just wants to spin the tires!!

I must ask after putting the Itercooler back on I feel that the coupler is able to slide if I put force on it. Is this normal I know that the intercooler stays in place but the coupler on the opposite side wont budge at all when tightened but the driver side coupler will move. ANY INSIGHT?

Thanks,
Mark

 

I take the second part back about the intercooler coupler i just checked again and it seems just as tight as the other side.


Thanks,

Mark

 

The rubber insulators and/or couplers might slide around under force if the surfaces are slick. Remember there is a small amount of oil on the inside of everything from blowby. Perhaps a small amount of some viscuous fluid ended up on the outside as well.

 

I viewed the disassembly of the intercooler and boots as an opportunity to clean them, so mine went back together without slippery boots....

HTH!

C ya,
Dutch

 

Everything worked out Great and the butt dyno really likes the mod. I do not have a boost gauge but will be getting a scangauge soon as Im tired of not having an ect gauge and its annoying to put the car into test mode all the time just to view the coolant temp. (That is how i figured out my low speed fan was burnt lol)

Thanks Again for all the help!

Mark

 

Hate to re-awaken an old thread....

I had the yo-yo...

i didn't really understand what exactly the "yo-yo" is (aside from a spinning split cylinder on a string), and i really couldn't find any answers to what it is exactly... till i found this thread.

So anyway.. i bought a DTBPV thinking that would solve my bogging in first, and if not, at least give me more boost! Well, it gave me more boost, and did not solve my yo-yo. Reading through the end of this thread, it says to NOT do the VGS with a DTBPV... Is this because the VGS vacuum is too weak to overcome the DTBPV spring?

Well, i went against the better judgment of a few people, and performed the VGS fix...

I can't f*cking believe how much better my vehicle is. so much power. excuse my language, but; Holy Horsesh*t Batman, why didn't MINI do this to begin with?

any thoughts on the VGS and DTBPV?

thanks.

 

Well, it's like reinventing the wheel over-and-over. The DT BPV is supposed to correct the yo-yo issues while also fix the fact the OEM BPV is does not shut flush (which can be corrected by adjusting the stop screw). Some MINI owners don't like the stronger spring in the DT BPV and put their OEM unit back on. I think I'm learning that you can pretty-much do any combination of the mods there-of. Since the VGS mod is not too involved, it's kind-of like "why not try it anyway."

Glad yours works that well.

 

yep. Works great!

I really like the combo of the instant type boost, and the smooth acceleration.


i don't think ill be taking it off. ;]

 

I did the VGS mod and removed it! I just couldn't get used to the ''engine breaking'' when you release the gas pedal!

 

Yeah, that's something you do have to get used to. But the hard engine braking on deceleration can be a good thing. My best advice is to go out and do some twisties taching 3500-4000 RPM with hard accelerations between 3rd and 4th gear.

 

ha, engine braking...? i drive a 6 speed. engine braking happens weather i like it or not.

 

one of the things that a lot of auto mags knocked the MINI for when it came out was the LACK of engine braking and slow rev drop when shifting gears with the stock set up!

Matt

 

Ok I will definitely have to try this mod now. I too have a DT Bypass Valve, and my car had no yo-yo before on stock BPV, but does now. Hopefully this mod will get rid of this effect for me as well

 

I am amazed at how well this worked. I have been trying to figure out why my 03 MCS has become such a pain to drive for a while. No answers from the dealer, changed fuel filter, did Seafoam, etc. This mod made such a huge difference. Drivability at the low low end of the throttle, is just a million times better. Thanks, I owe you a beer!