Recently I've been cycling through my profec-b occasionally and noticed that my max boost reading was way over what it should have been. So i'd go out and do some 4th gear pulls and the boost would reach target and hold...just as it should.

I thought this was weird, until last night I realized it was happening. I was at WOT in a parking garage (dont ask lol) in 2nd and I felt this HUGE surge of power. Looked at the profec and last peak boost was 13.9 psi(target is 9psi)! Luckily this was at lower RPMs, so it didn't detonate. I immediately tried to reproduce it and the wastegate opened at target boost.

So I think either my wastegate is sticking, or something is wrong with the profec solenoid. Changing to more conservative settings on the profec has no effect, and it doesn't seem to do this in normal circumstances where I start before spool RPM and run up to 7500 or wherever I want to shift. It does do it when at netural throttle above 5k or so and then I lay into it (as in coming out of a turn at speed)

the profec settings are:

set - 31%
gain - 5%
set gain - 5.5 psi

..I've been pretty dissapointed with the profec-b spec II recently as I've tried to hunt this problem down. I'm going to look into controlling boost with the interceptor-x, or get a new boost controller all together.

 

start by getting rid of the profec.

if it doesn't do it again, it's your profec. if it does, it's some other problem.

easy way to rule it out of the equation.

 

HKS EVC is WAY better. Pulled my Profec B Spec II for it. Seems like a lot of your other stuff is HKS, might as well complete the circle & upgrade.

 

I had boost spikes before I moved my boost sensor line from the intake manifold to just downstream of the intercooler.

Also, you're most likely to detonate at whatever RPM you're making max torque, which is usually mid-RPMs. So, you were tre lucky!

 

right now my pressure line for both the interceptor and the profec are connected to the VFAD nipple just behind the throttle body...what exactly is the rational for moving it in front of the TB?

in hindsight, I wish I had bought a better boost controller. at the time though I was broke from the turbo. I'm going to drive around with it off and try and reproduce the spike. If it still does it. then I'll see if there's a problem with the wastegate. If not then I'll look into other options

now it just needs to stop raining so I can do some testing

 

See MM's problem/fix #2: https://www.rx8club.com/series-i-major-horsepower-upgrades-93/definitive-greddy-turbo-fixes-here-they-81825/

 

I have the COM line on the solenoid plummed directly to the compressor, and the pressure sensor line to the profec itself plummed to the VFAD nipple. The NO line runs to the wastegate. At part throttle/vacuum the profec will not interfere with the wastegate (since it's connected to normally open), so it will open and keep the turbo speed down.

I doubt this issue is that of the configuration of the components. The installation was done by a very reputable shop (Mazsport) and it seems to be rare..