If Mr. Luchsinger knows what he's saying, this is an unacceptable position for MINI/BMWUSA to stand on. Admitting a drivability problem and stating that there is absolutly nothing they plan on doing about it?! Completely unacceptable!! There is no good reason why the MCS should exhibit this drivability characteristic if it was designed correctly.

Last night I met the VP of PR of MINIUSA at the Motor City MINI Open House. We exchanged information, and he was appauled with my MINI's problem and any dealership's abilty to solve it. He said he will contact the Product Management group and will get back to me. Speaking of which, Mark Ferguson's Product Management contact at MINIUSA has yet to approach me on this issue.

 

Has your car been flashed with v36 mr beerbrewer?
Have you spoken to your dealer about it?
Sorry to hear about your severe yoyo, good luck.

 

Mine has always had the Yo-Yo (july 03 build), and I would believe all MCS's have it. Just the luck of driving circumstances at around 2k rpm make it rear it's ugly head. I can make it happen in 1st, 2nd, 3rd, and 4th if I try. The Powerchip software made the yo-yo less noticeable and more rapid in it's pulse.

Great threads and research, I am eager to read more as knowledge or solutions come to llight. MotorCity Mini is 4 hours away and my car is buried in a couple of feet of snow in my barn until spring, so I am very patient.

I knew about this problem before I bought the car. I am a bit miffed it has been production for 2 years (3 in europe?) and no changes, patches, recall?!?

Do the JCW packaged cars have the Yo-Yo problem?!?

 

I can honestly tell you guys my car does not yoyo once it warms up. I have not driven the car in hot weather yet since having v36 flashed so that remains a question. I have a 15% reduction pulley and an alta intake wich made a very dramatic improvement from stock. It was real bad before, after the modifications it would only stumble in first gear on the first take off even after warm up or in first gear while making sharp take off turns even at optimal operating temp. The yoyo use to happen between 2500 and 3500 rpm but it would go away once fully warmed up. Same thing now with v36, no yoyo once it fully warms up. I'm not trying to cotradict or antagonize anybody here I'm just sharing my experience in hopes of contribuiting information.

 

I've noticed that since I've given V36 a few hundred miles to work it's adaptive logic magic, I too notice that the Yo-Yo is dramatically reduced when the engine is nice-n-hot, even during the past few days when outside ambient is 9F!

I've also noticed something strange. It seems my bypass valve has been sticking ever so delicately of late. My throttle response sometimes mimics a turbo. I'll be pushing the pedal progressively, and the engine does nothing....nothing...nothing, and then BAM! the power kicks in! Clearly further research is needed.

 

>>I had v36 loaded on my car. Got to meet Ilya, he treated me well. Spoke to Bill at MCM this too also very nice. My car was not ready. No fault of there own, a mouse has decided to make a nice winter home in my car and has helped himself to some lovely snacks. Non-waranty repairs of course. The parts are on order. MCM called the contact number I gave them, so I don't blame them. This was my first visit to the new building and I have to say it was pretty positive. :smile: They took it upon themselves to fix my sunroof rattles, eventhough I didn't ask them too. I guess they are showing off since there lessons learned on Christians car ? Thanks Christian, sorry you had to the guiney pig.
>>
>>My car has a much improved yo-yo so far and no sign of a stumble. Every time I took off, I intentionally tried to make it yo-yo. Out 15-20 take offs, I succeded once, and only once. I am baffled why it hasn't improved it for everyone. If my car stays this way throughout next summer, it would be tolerable. I hope it stays this way and that the mouse in my garage dosen't suffer too much this evening.
>>


Ok, I must revise this post.

First, it was very nice of MCM to offer to fix my Sunroof rattle, especially since I didn't ask them too. Unfourtunatley, they have made it much worse. Whatever they did has fixed any rattling that occured when the roof is open, however it never rattled when closed before, and now it does. Standing outside the car you can see that the 2 pieces of glass no longer appear to be on the same plain. The front piece no longer lays flat, in relation to the back. In reading the service order receipt they removed my glass, lubed the tracks, adjusted something and put it back. I can now cause the glass to rattle with my hand. Not very impressive, at all.

Secondly, my car does still yo-yo, quite often. It appears to happen at a narrower window of throttle position, but is still repeatable. My big toe TPS was unable to recreate at the same throttle position, so intially I thought it was gone, but it's just in a different palce.

It would appear that my PCV hose is quite mushy and so saturated with oil that it appears wet. I haven't yet had someone watch the hose to see if in fact it collapses during vacum. I will ask then too replace it either way.

I have to downgrade my previous comments about my visit to MCM from positive, to mildly disapointing. While doing my software upgrade would have been the perfect time to offer my one time configuration of convenience features as well. Obviously that never happened, let's see if they try to charge for me it next Monday when the mouse damage and vanity mirror are replaced.

I will have to do a search on the felt fix for the sunroof as well, I don't know that I want whoever adjusted it at the dealer to take another crak it at.

 

Ryephile --

I was wondering whether you know if the '04 JCW MCS exhibits the yo-yo?

If it does not...
...then we know the changes made as part of the JCW kit, yes? Any intersection between the parts list/installation procedure and the areas identified by your research may help to give us a clue. Perhaps this approach is not valid or too simplistic, though.

Just a thought...

 

I'm no tech guru, but the v36 definatly improves the slow coast hic-up.

 

Another stab in the dark.

The PCV hose has been reported to collapse during vacuum. Since the yo-yo is aparently occuring at the transition between vacuum and boost, is it a possible player in all this ?

 

--->Koopah, the JCW is not immune to the Yo-Yo.
The JCW kit (in it's core) consists of
A) 13.8% smaller supercharger pulley
B) ported cylinder head
C) different ECU mapping
D) colder range spark plugs
E) high-flow exhuast

With exception of the head-work, I've ruled out all of the above components as an integral part of the Yo-Yo.

--->gmack; the elephantitis you're experiencing only occurs under heavy vaccum, not during the transition between vacuum and boost. BTW, MINI has released an updated part for that PCV hose which is much firmer (my 10/03 build has it)

I spoke with Randy Webb yesterday, and he has found that just about every '04 that he's driven to date have the Yo-Yo. He's also found one customers car that exhibited the Yo-Yo under WOT! This certainly throws a wrench in the whole ordeal.

 

Ryan,
Thanks for the thoughtful analysis. I have an 04 MCS and the yo-yo bothers me as well. I suspect throttle butterfly pulsating due to the control loop - to much gain in the loop. Maybe the granularity in the movements of the stepping motor, or whatever actuates the butterfly, could be a problem.
But, if this were the case, you'd think that the fix would not be so tough or take so long.
It does make me with they had just used a simpler implementation.
Adrian

 

Ryan,
Thanks for the thoughtful analysis. I have an 04 MCS and the yo-yo bothers me as well. I suspect throttle butterfly pulsating due to the control loop - too much gain in the loop. Maybe the granularity in the movements of the stepping motor, or whatever actuates the butterfly, could be a problem.
But, if this were the case, you'd think that the fix would not be so tough or take so long.
It does make me wish they had just used a simpler implementation.
Adrian

 

Not sure if this is the same issue you guys are talking about, but I have an issue with my MINI as well. About 2 weeks ago while accelerating on to the express way in 4th gear, I started to feel a slight hesitation. My car is a year old, 11/02 build, 12/02 pick up, 2003 model. Thinking it was a one time thing, because I had NEVER experienced this before, I blew it off. Wrong. It continued in every gear, at any rpm, full throttle, 3/4 throttle, any time I applied a lot of throttle the car would hesitate. Is this the stumble people talk about? Or is this the yo-yo? Well the great people at Bill Jacobs MINI had me come in for version 36 today and they upgraded me in about an hour. So I pull out of the lot, and nothing but smooth sailing, for about a mile, then under the same conditions the hesitation came back. I live 50 minutes from the dealership, so instead of turning around I kept going because I had to get some things done. Well, once on the express way the hesitation disappeared. CPU had to calibrate with the car? Who knows, but when I got to the side streets, the hesitation was back. Under cruising speeds, no hesitation. Under easy acceleration, not hesitation. I was hesitation free for a full year, and now I have it. Is this what everyone else is experiencing? Sorry this is so long.

Craig

 

--->cooper44, sounds like you indeed may be experiencing the Yo-Yo. Not so much a hesitation but a wavering or oscillation in acceleration.

YO-YO SOLVED!!!!
Tonight I disconnected the vacuum pump linkage from the bypass valve, and then zip-tied the linkage such that the butterfly is permanently closed. Go for a test drive (DSC off, of course), and VIOLA! No Yo-Yo! I'm hugely skeptical, so I continue on, stopping and then running through the gears again and again. Gone, nothing but smooth, no wait, BUTTAH smooth acceleration, regardless of pedal position or technique.

Now, because the bypass valve is closed, there is a possibility my fuel economy may suffer a bit. Also, NVH is up a notch because you now hear the supercharger whine 100% of the time instead of on-boost only. The car also behaves differently. If you've ever driven a big-cube engine (read; small block Chevy or Ford) with a big 6-71 or bigger Roots blower, this is more so what the MCS drives like now. A bit more attitude, definitely more connected feeling.

So, the next step is to determine if my bypass valve itself is faulty, or if the design in general is faulty, since so many MCS's have this issue. I noticed the butterfly needed tension to stay fully closed (spring loaded just in the last 5-10 degrees of closure). This could interplay with the aerodynamics and acoustics, creating a resonance in the circuit and subsequent Yo-Yo due to the bypass valve butterfly resonating. The fact that the Yo-Yo changes frequency over the RPM range would dictate that acoustics don't play a part in the overall circuit but more of a fundamental airflow issue and/or the spring-loaded closure for the butterfly.

Clearly, MINI has some work to figure out. At the minimum, they will post a service bulletin with a new part number(s), or they may issue a recall. Whew! We're finally on the down slope!

Cheers,
Ryan

 

Great work Rye. Noticed you made test runs with DSC off. Just to be sure its not a factor, you may want to make a couple of test runs with DSC on. Could you post a picture of where you disconnectedm the linkage.

 

>>YO-YO SOLVED!!!!
>>Tonight I disconnected the vacuum pump linkage from the bypass valve, and then zip-tied the linkage such that the butterfly is permanently closed.

Ryan -- could you post a photo so that the rest of us can tune into the same wavelength?

Thanks -- Tom

 

Here ya go, just snapped a few minutes ago :smile:



Notice the bypass valve is inboard of the throttle body, situated between the exit of the throttle body and the exit of the intercooler. Sorry for the crappy focus, hopefully you can see it good enough. The vacuum pump is connected to the bypass butterfly by a tie-rod linkage. I disconnected that tie-rod, and the zip-tied the ball-joint to the adjustment setscrew for the butterfly stop.

I don't really recommend doing this unless you are:
A) a skilled mechanic
B) prepared to shell out cash if you accidentally break the ball cup of the tie rod (which is plastic)
C) desperate to rid yourself of the yo-yo at any cost, including sacrificing fuel economy until MINIUSA shells out a better part and/or fix.

Cheers,
Ryan

 

Hey Ryan,
Do you mean that this mod actually makes your Mini MORE tractable? Why don't we all do it then? I'd be willing to give a couple of mpg for better drivability, even if I didn't have the yo yo.
Sid

 

>>Not sure if this is the same issue you guys are talking about, but I have an issue with my MINI as well. About 2 weeks ago while accelerating on to the express way in 4th gear, I started to feel a slight hesitation. My car is a year old, 11/02 build, 12/02 pick up, 2003 model. Thinking it was a one time thing, because I had NEVER experienced this before, I blew it off. Wrong. It continued in every gear, at any rpm, full throttle, 3/4 throttle, any time I applied a lot of throttle the car would hesitate. Is this the stumble people talk about? Or is this the yo-yo? Well the great people at Bill Jacobs MINI had me come in for version 36 today and they upgraded me in about an hour. So I pull out of the lot, and nothing but smooth sailing, for about a mile, then under the same conditions the hesitation came back. I live 50 minutes from the dealership, so instead of turning around I kept going because I had to get some things done. Well, once on the express way the hesitation disappeared. CPU had to calibrate with the car? Who knows, but when I got to the side streets, the hesitation was back. Under cruising speeds, no hesitation. Under easy acceleration, not hesitation. I was hesitation free for a full year, and now I have it. Is this what everyone else is experiencing? Sorry this is so long.
>>
>>Craig


Craig,

Please don't take this the wrong way. When I read your post though, it kinda sounds like what your are describing is your traction control or DSC kicking in. Turn it off and repeat the same experiment in a controlled environment, like a empty parking lot. I am guessing the hesitation will be replaced with wheelspin. I notice your in the Chicago area and it would make sense that you could go through the summer without it being as noticable.

Define hesitaion better please, are we talking about the car actualy pausing for a second, then taking off. If so that sounds like traction control.

 

Ryan, I realize this is in the Beneath the Bonnet forum but could you explain this in laymans terms? Is the butterfly valve the issue? What is it's purpose if you can disconnect with no ill effects?

 

WAY TO GO RYAN!!! I certainly hope that MINIusa is reading and following this. Why couldn't the technicians come up with this diagnosis? Let's hope that a fix is in the works and it won't take as long as the stumble issue to be resolved.

Cheers,

JD

 

Ryan is the big winner today! Hooray!

Now if can we get Mini to complete the mop up operation with a recal/repair solution.

 

I've noticed something - when you step on the throttle a certain amount, the throttle body (reading via boost gauge) overshoots before setting on the input value. I chatted it up with my engine management co-worker today. According to his theory, seems that the overshoot is the result of poor P.I.D. throttle body servo controller tuning, resulting not in a "critically damped" response but a "ringing" response (aka too high a Q).

This overshoot could be the root cause of the Yo-Yo. In conjunction with the unstable "fighting-springs" of the bypass-valve assembly, the Yo-Yo is created. The overshoot of the throttle servo is plainly wrong in terms of the circuit tuning, and whoever designed it should be thoroughly smacked. My Co-worker said this overshoot is a classic "3rd year bachelors degree type problem), and is inexcusable for a company of BMW's engineering caliber. I had a chuckle.

Wednesday, My dealership is sending this thread off to their Engineering Channel at MINIUSA. Hopefully they already have a fix in the works, but if not, they'll be in for a good pile of data!

--->mini58, sorry for the technical terms! Try re-reading the first post here and hopefully I was consise enough for it to make "layman" sense.
Cheers,
Ryan

 

gmack,
no offense taken, but it definitely isn't the traction control. it happens when i'm on the express way, and mostly when the rpm's are low and i'm in a big gear and instead of down shifting i just gas it. i did notice that with the heat wave we had here today in chicago (38 degrees) it didn't happen as much, and then not at all when the car was fully heated up. thanks for bringing it up about the dsc though.

ryan,
is this similar the the diverter valve issues vw's have?


craig

 

Ryephile --

Congratulations. I have also sent you a regular email!

But tell me, would "the fix" be a change to the ECU software or the servo or both?