I hope this isn't beating a dead horse but I've got the problem and I've read a bunch of the older threads. I'm not so much concerned about HOW to fix it because I'm not very mechanically inclined. What I want to know is how you all talked to your dealers and what you said to them to get them to pay attention to you. I don't have but about 1500 miles on my S and it is REALLY bad at the 2700 to 3300 RPM range.

 

We had a problem, and the dealer would not help. My husband had to call MINI USA directly.............

 

What did M-USA do for you?

 

They spoke with the dealer and actually sent an engineer out there. It was a long process.

 

Was the yo-yo problem resolved?

 

It was a brake problem, and it was resolved, but it would not have been if we hadn't gone to MINI directly (around the dealer). That was what I meant.... (just an idea)

 

I haven't gone to the dealer with this yet, but I sure do notice it. Buying a car is like building a house. You have to do a punch list!!!

 

The actual cause of the yo-yo effect has yet to be corrected by MINI and cannot be fixed by your dealer. The problem is buried in the software that processes certain sensors and devices. The result of these software issues is the unintended oscillation of the supercharger bypass valve (via changing vacuum levels) which cuts boost in the RPM range you describe. The correct fix is to change the code (dampening algorithms) at the component level; MINI have not yet done that (and likely won't with the new engine on the horizon).

Instead, MINI have tried to "mask" the yo-yo with new versions of the ECU code. This has helped somewhat, but hasn't addressed the component-level software issues. Note that some MCSs seem not to have the yo-yo; others do. There may also be a "driver sensitivity" component to the variance in yo-yo severity.

My 2004 MCS was a yo-yo prone MINI. I've tried ECU versions, a stiffer bypass valve return spring and the VGS solution. The ecu code lessened the severity of the yo-yo, but did not eliminate it. The stiffer bypass return spring (a.k.a. the Ryephix#2) almost completely eliminated the yo-yo. The VGS solution (replacing the standard vacuum source with a feed from the Fuel Pressure Valve line) completely eliminated my yo-yo (YMMV).

While both the Ryephix#2 and the VGS are potential solutions that mask the yo-yo effect, the VGS may be simplest to install. However, it changes some of the throttle characteristics. Basically, partial throttle (angle) performance is a bit altered: it seems rather sensitive and feels as though the bypass valve is rather slow to close. However, as you increase the throttle angle, the bypass valve clamps shut and the increase in torque is very linear...and no hint of a yo-yo on my MCS.

The VGS costs less than $10 in parts (vacuum hose, tees) and takes less that a hour to install (intercooler removal/installation takes a bit of time). There is a great thread on this if you search for "vacuum gain system".

Hope this helps,

Theo

 

Thanks for your great reply. Do you think that I should try to get the dealer to upgrade the software or just not even bother and go for the other fixes?

I'm sure part of the problem is just that I'm sensitive to it. If I'm just doing daily driving I notice it a lot. If I'm out having "fun" I don't notice it hardly at all. Torque seems to mask it I suppose.

This is my only major problem with the car. Everything else is so small that I can wait on it till the first service.

I love my MINI and am looking forward to starting a few mods.

 

VGS is easy, cheap and ~ 99% effective. Do it.

 

Agreed!

Try the VGS instead of a new ECU version.

Theo

 

OK, you guys have convinced me. I read over the VGS thread with all the pictures and I still don't know what I'm looking at but I'll go buy the stuff and print out the pictures. I figure if I can put a computer together I can do this. Hopefully there won't be any parts left over!!!

 

VGS changed nothing on my car, I must be the 1%. I checked the routing twice and everything is properly attached, it had no positive impact whatsoever... I'm going back and will probably try the Detroit BPV.

 

I would strongly recommend that when you put the new hose on the Fuel Pressure Valve, you use a very slightly snugged-up zip-tie on the new piece of vaccum hose that attaches to the nipple underneath the Valve. Without the zip-tie, mine came off after 100 miles or so. I had to snug-up the zip-tie in little increments until it was secure. No problems since.

Oh, and also...

If you have the JCW CAI, you will notice a "Y" fitting in the vacuum hose near the BPV. The VGS thread has instruction on how to handle this.

Wow, that's unusual! But then again, sometimes it's nice to feel "special"

Cheers,

Theo

 

I'm gonna revive the Yo-Yo discussion if I may...

I seem to recall people on here being told it was due to the formula of gas during the summer months. Well it's Feb. and I still have the yo-yo on my '05 S. Here's an update: My wife got a VERY nice '06 S as a loaner recently, and it had NO SIGN of the yo-yo. She even said to me "this S isn't faster than yours, but it's a lot smoother." GRRRRR!

Could this mean the '06 software has cured the yo-yo? If so, a reflash at the dealer should help older models.

 

Seems that we need to talk to the dealers. Mine hasn't given me as much problem in the colder weather, but on warm days it is noticeable.

 

I've written some on the YoYo, and have the VGS and RyePhix. I talked with the Service Manager here once and he recognized the problem and symptons, but said there was nothing he would/could do for me. His only suggestion was an ECU flash--but I wasn't going there (my Unichip and V40-whatever is working just fine, and there's no evidence that the OEM software flashes solve this problem.)
Just because the 06 loaner doesnt' do it, doesn't mean the latest flash has solved the problem. IMO the problem is not a software one, it's a physical problem: the bypass valve actuating "mechanism" oscillates due to the location of the vacuum takeoff so close to the valve. And many stock valves do not seat correctly. I have talked with many of the NM Club members and no one else has noticed or suffered the problem as I did, which suggests it varies from car to car, and that some people are incredibly insensitive to the effect if it's present.
If it bothers you, do the VGS and see how it works. It's cheap, easy to do (if you can build a computer it's easy) and completely reversible. So waste an hour and 10 bucks for the cheap thrill of seeing what's under your IC, and maybe fixing the YoYo.

cheers,
phil