Hey guys, I'm having a rather weird issue.
First its a 08/06 build Cooper S, 115k miles with only mod being a DDM intake
Second it has no codes
Now what is has been doing at part throttle is like a fluctuating power/noise, you can feel almost yo-yoing. With the DDM intake I can hear the intake pulling in air, and today with the window down I heard the air go from normal sucking noise then go away then repeat all under the same part throttle. This happens at a normal rate, its not a slow process but you can clearly hear it doing something.
Another thing, I have a ultragauge set to read boost psi, and when its acting normal its reading 7.5-8.2 psi, but when it fluctuates, it drops to 5 psi and goes back up and repeats

My question, Is this a sign of the bypass valve going out? or perhaps the belt?
I'm new to mini's, If someone could shed some light, that would be great

 

Could be the BPV. Try resetting the ecu first, sometimes that clears up stuff like that.

 

I did reset it using both the battery disconnect and the reset though the trip odometer, I think it is the BPV but it seems odd with an late 06 build. Thank you for the input.

 

Hmm. Well, push on the BPV spring. It's right there, you can see it. See if its soft or something

Do u have a JCW? Maybe look at the hose going to the BPV, see if there are any cracks or something.

 

It is not a jcw, bone stock with a DDM, I pushed on the lever to turn it and it has good tension, nothing that seemed too soft to me. I'll look at the vacuum line tomorrow. Could the IC boots be an issue?

 

Did you first notice this after installing the CAI.

 

It was doing it before the CAI as well, just more noticeable now with it

 

Update: So today I was looking at the mini's pulley/belt and noticed I have a alta 15% SC pulley and a alta crank pulley. I had already ordered a 17% and a new bypass valve so I will have 15 alta pulley for sale if anyone is interested. When I got my new bypass valve spring felt much stiffer than the one that's on it, like my at least x4.