I've read dozens of threads on the dreaded 'yoyo effect' and I don't really understand what it is. However, after a couple weeks and about 1k miles on my new (used) mini, I feel like I am experiencing the same thing. When accelerating normally (i.e. not really getting on it), the powerband seems very choppy, especially at low rpms under 3k. Nothing is very smooth about the way my MCS accelerates from a stop. Is this the yoyo effect?

 

Yep.......varies from a slight pulsing feel to an almost bucking bronco one.

 

well, there's an easy, quickj and cheap fix..just change up at 4k....LOL..

Hahah..on the serious note...how do we fix this Yo-Yo like symptoms?

 

Many, many, many, many, many...........and many more threads on it. Just google search NAM for yoyo

 

^^ thanks...I always seem to forget bout the search function..

okay, from my quick browse thro' here are some things that fixed for the yo-yo

- VGS
- Detroit Tuned BPV
- GIAC
- New OEM BPV

so, no one equipment will gurantee a 100% fix...

 

Not Detroit Tuned TB - Detroit Tuned BPV.

Add to the list "new OEM BPV", which also often works on older MINIs.

 

Opsey..thanks for that...but thats what i meant....hmmm....so, what do you recommend us older Minis owners (i have a prefacelift 2004) to use? new OEM BPV? or the DT one?

 

"It depends"


Some of the older BPV's I've felt have noticeably weaker springs than the newer ones... it's likely that either would be an improvement if you have an older BPV with a weak spring exhibiting yoyo. The DT one provides more of a "binary" on/off feel for boost, and runs under boost more of the time.

 

Can you explain in terms of sensation?

 

I thought it was the guy behind the steering wheel.

 

Varies from a very subtle cyclical "surge and ebb" in accelleration when under throttle (vs. a smooth accelleration as expected) to a more extreme "bucking" sensation of the car lurching forward and back while under throttle.

If you have a boost gauge, the telltale symptom is the inability to hold the boost steady at about half boost at part throttle - around 7-8 psi. The boost will surge on and off at this point. That's a sure sign of "yo-yo".

 

I'm getting yo-yo at about 3500 rpm and 5-10psi even after replacing BPV with new OEM BPV. What is causing it - Any other suggestions for fixing this? Trying to figure out what could be pulling the valve open.

 

I have seen instances where someone has changed the HT leads with success in resolving their issue. Worked for this individual, last post HERE. Another individual HERE said there's was a result of a broken throttle housing. Just to give you some other areas to check out possibly. Good luck.