So apparently my boost is oscillating. Only at higher rpms at nearing peak boost. I think i have an idea on how to fix this. I am running a .6 or a .7 bar spring and an apexi power fc boost control kit. It runs the same solenoid as the profec b spec 2 and the avcr. The boost is going between like 13 and 15 near redline. Have any of the rest of you ran into this before? Thanks.

--Hank

 

I'm not familiar with the power fc boost controller, but it sounds like you need to turn the sensitivity (gain) down.

 

first, check your wastegate plumbing. Make sure everything is hooked up correctly: did you set the solenoid for external wastegate (this involves hooking up the vacuum line to the NC port)? Once everything else is verified good, go into your commander or datalogit and set the "duty" number a few percent lower, do a pull and see if it improves, and just keep trying that.

 

Ok so what i was thinking is that i have to get a stiffer wastegate spring. What i'm thinking is that i am getting near the threshold of the boost controller. Meaning that i am at nearly double what the spring is rated for so it isnt responding as well as it could with say a slightly stiffer spring. Let me know if that is a sound idea.

 

In my experience with tuning a few boost controllers..i would agree with this at first guess by what you said. id check that before you start spending money/swapping parts

 

No matter what your setup is, the PFC boost controller will never run right if you don't tune the duty cycle.

 

More than likely a combination of the two. First make your adjustments with your BC. But as a general rule you should try and keep your spring within a few pounds of desired pressure. Example would be If your trying to run 15psi run a 13psi spring not a 7psi spring.

 

I had some pretty bad oscillation with my boost control (stock twins, non sequential) when I initially got my car back from the person who previously worked on my car. It would oscillate about +/- 2 psi as seen on my analog boost gauge and EBC (I wanted 11 psi, got 9-13!). I have a Greddy Profec B Spec II EBC. Not sure how much different the results would be with an external wastegate single turbo...

So I turned the gain down significantly, and then then had boost falling off up top. I've sinced got the boost solid up to redline, just had to switch the gain up/down until I had solid boost pressure.