>>>>Super_MINI: This will throw a wrench in the theory: My lightweight summer wheel/tire setup (36 pounds a corner) seems to make the Yo-Yo more obvious than my 41-pound/corner winter setup. How's that for contradiction!
>>>>
>>>>...continues scratching head,
>>>>Ryan
>>
>>I suppose it's no more of a contradiction than the fact that some cars have it and some cars don't. Plus I went even further, 50lbs per corner down to 38lbs and reduced the rolling diameter by 1.2". It literally feels like I lifted 500lbs from the car. The acceleration difference Is like I let 3 adult passangers out of the car. I'm implying no more than this is an observation on my vehicle, thought it might help.
>>
>>
>>
>>
>>
>>_________________
>>


1.2" off diameter!!!!!!
wow did you notice any speed change?

 

The MPH is off by less than 3mph at 60mph, so it's not bad at all. I just keep that in mind when cruising the Highway. Acceleration is much better with the smaller/lighter wheels and tires. I'm very happy with the setup and in 6th gear on the highway the engine is only at a slightly higher RPM than before to maintain the same speed. My Miata would have been over 4k rpm at highway speeds. MINI is just over 3K.

Yo-Yo update so this doesn't turn into a hijacked post. My Yo-Yo has returned after taking a weeks vacation. It's not as bad as before and it appears at lighter throttle acceleration. But still there... I want it gone!

 

I agree with your observations Super_MINI - the more performance mods (engine, lite wheels) I do, the sooner in the throttle position the Yo-Yo occurs.

Stock - almost to full throttle when the Yo-Yo is most prominent
fully modded - closer to half throttle

 

>>I agree with your observations Super_MINI - the more performance mods (engine, lite wheels) I do, the sooner in the throttle position the Yo-Yo occurs.
>>
>>Stock - almost to full throttle when the Yo-Yo is most prominent
>>fully modded - closer to half throttle

That's interesting. Are you pretty certain about this throttle information? Mine is still stock and haven't felt the Yo-Yo, yet, but I also don't go full throttle that often (only 2500 miles on the Odo). That would be interesting information for MINI to reproduce. Has anyone with JCW had Yo-Yo? Unless they replace this spring one might expect similar results as you stated above. Good info

 

I'm not pretty certain - I'm absolutely sure the throttle position of the PID overshoot "break point" shifted downward the more HP the engine has.

Do you think this is related to the torque calculator? I'm not sure if any JCW have claimed this issue, but from bone-stock to pulley'd+, I've driven MCS's that Yo-Yo regardless of engine mods, so there is no reason a JCW would be immune.

Ok, I think I need to clear the air a bit here. There seem to be three issues at hand:
1) the Yo-Yo - the oscillation of the bypass valve
2) the PID overshoot - a transient miscalculation that causes more throttle butterfly angle than the throttle pedal input.
3) the Break-point - the point in the throttle angle position where the ECU "snaps" the e-gas to WOT regardless of throttle pedal position relative to "floored". I've always noticed this phenomenon, but for a while thought it to be bypass-valve related. After doing bypass-valve modifications (tying shut or stiffer spring), this phenomenon was still present, indicating an e-gas issue.

The Yo-Yo by itself is strictly bypass-valve related, HOWEVER, it may be assisted by the PID overshoot, and even the Break-point. Basically, it seems there is a lot of work to be done on the e-gas tuning! Does any of this correlate to other Yo-Yo sufferers?

Yikes,
Ryan

 

I've never experienced "PID Overshoot" or "Break-Point". I had very bad stumble that was fixed with V36. I also wonder if the ECU may be somehow causing the SC Valve occilation because my Yo-Yo was truely gone for about a week after installing the lighter/smaller wheels and tires. Seemed like the ECU spent time readjusting to the lighter wheel setup (if that makes any sense). I've also heard others claim that aftermarket ECU upgrdes solved their Yo-Yo. The lead tech at my MINI dealer also owns Wallis Motor Sports and he claims if I upgrade to their ECU that my Yo-Yo will be gone.

 

>>[quote]
>>The Yo-Yo by itself is strictly bypass-valve related, HOWEVER, it may be assisted by the PID overshoot, and even the Break-point. Basically, it seems there is a lot of work to be done on the e-gas tuning! Does any of this correlate to other Yo-Yo sufferers?
>>
>>Yikes,
>>Ryan


Ryan --

I had the Ryephix #1 on for only a couple of days (before removing prior to going on a road trip) so I'm not sure my experience is truly representative. The yo-yo was eliminated but I was expecting the "break-point" issue to come into play. I must say that in the short time I drove with the phix, I did not notice a severely non-linear throttle response. I'll re-phix again and let it go for several weeks just to double check.


_________________

 

does anyone have a 04 built that has this effect?

thanks

ant

 

I have an 04 MCS and I do experience the yo-yo only under moderate acceleration mostly in 2nd and 3rd gear. It feels like the throttle is slightly oscillating. And I believe that Ryan is right about the underlying cause.
I find it annoying in a car that is otherwise so well balanced and smooth.
Adrian

 

I have a MCS '04 build and I do have the yo-yo. Mine is felt around 3500-3900 rpm when accelerating heavily.
It is really annoying, feels like a car that needs fixing. Otherwise the car is almost perfect.

 

>>does anyone have a 04 built that has this effect?
>>
>>thanks
>>
>>ant


ant57 --

You'll find lots of '04 MCS owners here that have the problem. However, we did escape the stumble!

 

>>does anyone have a 04 built that has this effect?
>>
>>thanks
>>
>>ant
The official list is on the bottom of page 11 of this thread. I count around 18, 2004's that have the yo-yo problem. I'm sure there are more, but people haven't chimed in yet. Unfortunatly I'm on that list. :???:

 

Tomorrow AGOKART and I are putting the stock bypass valve back on, because Thursday I bring MM2 to the dealership. This is so I can rack up the number of times they've attempted to fix "the Yo-Yo effect". See where I'm going with this? If all else fails, I want the arsenal for Lemon Law at my fingertips. However, I feel a Class Action Suit would be more appropriate, since so many of us have this issue!

Question: I have basically no experience in the litigation arena; who can help with the Class Action stuff?

I have been leaving messages on PK's voicemail, however he has not called me back in weeks! I'd like to give MINIUSA a chance to "make it right", however the timing is dragging out, and they seem unwilling to provide useful information.

Annoyed,
Ryan

 

hey ryan,
i sent another email to the 'jen' the mini service advisor who has been calling me and responding to my emails. i'm annoyed too, she very nice and attentive but nothing is happening and so her attentiveness is easy to read as 'part of the plan'. bmw tells her that they will soon have a fix for the yo-yo but she does not give me a time.
thanks again for your tireless work and patience,
julia

 

I've always experienced the bad "Break-point" & it is absolutely driving me nutz! I fell as if I can't pull into traffic with confidence.

 

I have a question. Im picking up my 04mcs on 3/13. What should I do before giving him the money. I know I sould take it for a drive first, but if there is a yo-yo effect, they cant fix it, so should I just hand over the money and pray they will eventually come around with a fix. Or should I tell them fix it first then you'll get your money, dirtbag! This is all going off if it has the yoyo of course. Please let me know. :evil:

 

Tough question. Still a great little car, even with the yo-yo. They have addressed the coolant tank issue, the stumble and recently the cracked windshields. As long as people like Ryan and others keep the pressure on, I see no reason to believe this won't get resolved.
A unacceptable anoying condition that is getting alot of exposure, but not a deal breaker, imo. I don't notice it everyday. It does bother me when it happens however.

 

>Stock - almost to full throttle when the Yo-Yo is most prominent
>fully modded - closer to half throttle

I agree with this a lot, but am not really sure/knowledgeable about some of the more tech. reasons. Cruising down the road at constant speed around 2k-2.5k rpm in traffic I can actually feel the car doing a subtle 'surging' like a slow motion Yo-Yo. It is bizzare, or I just had too much coffee and am antsy to downshift and pass people.

 

I would suggest not to purchase your new MCS if it has the YoYo. Refuse to take the car until the issue is resolved. Yes, you may have to wait longer but you will not be dealing with the YoYo daily. I didn't read enough on here prior to my purchase to know. I thought it was me just getting use to the clutch or drive-by-wire of my '04 MCS but after reading more I realized I had the YoYo. I went back to the dealer, got the v36 update and hoped for the best but it was still there.

I was unhappy with a few other items the were unique to me and decided that the MCS was not the car for me at this time. If I would not have had the YoYo I may have tried to resolve some of the other issues but with it I didn't even want to try.

It is a very fun car to drive and the only car I liked that let me use my iPod via an AUX port.

_________________
Chris
'04 MCS: 1,2,3, aux guages, aux input, dk slvr, blk/lapis blue - 11/03 build - 12/22/03 delivery

 

Backwards Update: AGOKART and I put the stock bypass valve back on MM2 yesterday. We found a quicker way to replace it, yay! Pulled out of the garage and accelerated...BAM, first gear, there's the Yo-Yo back to haunt me. Seems to be just as annoying prominent as I recall. Thankfully, I only have to deal with it for a few days until I give MM2 back to the dealership. This will be attempt #4 to "fix the Yo-Yo". Obviously, unless they break into my house and steal my Ryephix #2 and install it, there's nothing they can do about it. Simply a paperwork-satisfying visit to Service.

I stopped by the dealership yesterday also, and drove their demo MCS. It figures, it didn't have the Yo-Yo, however it did have the Break-point, which is annoying enough :evil: I wonder if they hand-picked the demo-car so people wouldn't be test-driving a Yo-Yo effected MCS?

More update on Thursday when I drop off MM2, unless I can get in contact with MINIUSA beforehand,
Ryan

 

>> {snip}
>>I stopped by the dealership yesterday also, and drove their demo MCS. It figures, it didn't have the Yo-Yo, however it did have the Break-point, which is annoying enough :evil: I wonder if they hand-picked the demo-car so people wouldn't be test-driving a Yo-Yo effected MCS?



_________________

 

Besides, I can only hope the dealership does not want to risk being sued for "bait and switch"!

 

I have an '04 MCS, with a fairly negligible yo-yo. I haven't experienced anyone else's first hand, but from what I've read, mine doesn't seem that bad. It's only really promininent when the car's in warm-up mode.

Anyway, I'd go ahead and get the car despite the yo-yo anxieties. Of course you should drive it first, and decide for yorself if that particular car is drive-able. But generally speaking, the yo-yo's not a deal breaker.

 

I'll throw my VIN into the ring:

TD68280 - Apr. 03 build, delivery in June - stumble and yo-yo from day one.

v.36 fixed stumble - ryephix generally took care of yo-yo.

Smoother acceleration and mpg still ranging 25-28 mpg!

 

My dad was recently invited to join two class-action suites. One of them for the Honda CRV tranny issue, and one for a wood stain company. he thought they both were BS and didn't bother with the car, but went ahead and 'experiemented' with the stain company. after about a years worth of waiting and paperwork, they sent him two NICE checks.... HE had no idea there was even a problem with the stain until someone sent him paperwork in the mail basically inviting him to petition and join the class action.


I think you will be able to send paperwork to ALL mini owners, regardless of if they know of this site or not... give good description of the symptoms and many will probably contribute to the cause. You need a good attorney..... Anyone ever see Erin Brokovich...?.....