Author Topic: stage 2 wrx surpassing target boost  (Read 781 times)

Offline renny0203

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stage 2 wrx surpassing target boost
« on: November 27, 2013, 06:19:31 PM »
Hey guys and gals, i have an 02 wrx i bought with a cobb sf intake and invidia catless turboback exhaust.  I purchased an AP for it to have a basic ots stage 2 car.  i noticed after watching the boost guage on the ap that the car will spike much higher than the 15.8 target.  Ive seen it spike as high as 21lbs :-[  I did some datalogging and sent them to cobb, they responded saying the wastegate isnt functioning properly and that i either have a vacuum issue or the stock bcs is not working properly.  I did find a poor splice job in the line running from the intake elbow to the bcs and replaced it.  The other lines look fine.  still runs too much boost.  I thought maybe the previous owner had an mbc on it at one point and may have adjusted the arm on the wastegate to preload the spring to allow more boost quicker :-\.  I backed it off a couple turns at a time to see if i could get the spike down and at 5 turns it would still spike about 18 lbs.  I looked up picks of stock wastegate arms on the tdo4 and it looks like it was the right length before i adjusted it so i put it back to how it was (about 3/8 thread above the locking nut).  Im still learning turbo systems so bare with me haha.  Im thinking that maybe the stock bcs is bad?  Read that if ya plug the green connectors in under the dash for test mode, it should make a click sound.  I did that and had a buddy listen to it but with the fans and other things cycling on and off its really hard to tell if it makes any sound.  Sorry to write a book about it haha, didnt know if anyone else might have had this issue in the past, Thanks! :subaru:
2002 wrx
2009 wrx 5-door -SOLD
2014 Outback

Offline zombiez07

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Re: stage 2 wrx surpassing target boost
« Reply #1 on: December 02, 2013, 03:53:19 PM »
it's either the wastegate arm is still wrong (you can't really determine from pics as there is no way for a picture to capture spring load or slack and no two are alike) or your bcs crapped out.  if you lengthened the arm and it dropped the spike, i'd continue to lengthen it.  if that works, great.  otherwise i'd pin it squarely on the bcs.