AF's
 

anyone got air fuel ratios for the 3000 = 4000 flat spot area? if so what mods do you have ? are you experiencing the flat spot =yo yo ?

that area is where most mini's tend to shift from lean to rich, at least that has been what I have seen on most dyno plots.

According to some schools of thought, this is due to header design. You may want to ping DMH on this topic, he has mentioned this several times.

do they go way rich as in a dump? i'm thinkin' the ecu's seeing the flat spot late and dumping to get thru it . so it seams that pre boost could be lean country. at least in my situation . by adding the detroit bypass i think my car has gone lean prior to the ecu catching up . causing yo yo and flaaaaaaat spot.

Just for clarification, the yo-yo is a part throttle issue, not WOT. If your car is running anything but 14.7:1 AFR under part throttle, you've just won the lottery!

I'd really like to know how many have this "flat-spot" cause I certainly don't and I've driven several different Minis, all were 05+ though. One JCW that didnt either....

i've got massive hesitation, no power, no response, jumping revs etc below 3500 rpm, whether at full throttle or not. In fact, at full throttle, it's even worse. wtf is going on

thanks ; i know it's part throttle but let's say the ecu gets behind a bit could it not see a lean condition after you open the throttle but be slow in catching up?

i'm going back to stock bypass this weekend either i got a very strong spring with this one or i'm not making enough vacuum to open the transition valve(my new name for the bp). fully . it's like the car is trying to push through a wall at less than spirited driving ' . but in the 3000 range is where most of my comute is so gotta go with comfort on this one .

what's the ecu looking at for throttle responce ? throttle pos. manifold air pressure, pre- cat afr , of course temp., is the relationship between ecu and fly-by -wire that slow? or is running more boost on a partial throttle momentarily making the ecu go with throttle pos. which takes presidence?

see if it were a port issue alone then i wouldn't have a flat spot and massive hessitation after only doing a bpv. these are new to me . somebody smart has to look into this . just offering some testimony hoping someone will look into it .

I had to swap the spring on my DT BPV because it cause a huge flat spot on mine. Then again I have cam, headers and a host of other things most wont have. Everyone I know seems to love it and I have installed 5 or 6 of them

that's why it's such a dissapointment . everyone seems to love um. i'll look it over real good when i tear into it again couldn't find a vacuum leak but who knows ? gonna do some cai insulating anyway so it's not wasted time . that thread on cais is loooooong lotsa info .

I liked the boost it made down low, but the flat spot was just unliveable.

The VGS did the same thing.

The VGS and DT BPV just made the car buck like crazy.

that's what i get at times. sometimes though it's barely there but noticable. could be aticking. if it weren't such a pita i'd mess with it more to try to nail the bi$ch.