Greddy Type S BOV adjustment problem
05-29-2002, 06:37 PM
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Join Date: Apr 2002
Location: Malvern, PA
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Greddy Type S BOV adjustment problem
I ordered a Greddy Type-S Blow off valve, thinking I was doing the "right" thing but I can't get this darned thing to work properly.
I just bought a set of intercooler pipes, so I have one that has the Greddy flange installed on it. I bolted everything up, and installed the stock BOV vacuum signal hose (from the intake) to the Greddy BOV. The bottom port on the BOV was left open (to atmosphere). Even with the adjustment screw FULLY out (well, it's still "in" so that it seals the vacuum, but its not increasing spring tension) the turbo chatters and the BOV barely opens! I used a vacuum pump to test when the Greddy BOV was opening, and it wasn't starting to open until like 17 in hg! It wasn't fully opened until like 25 in hg! My car makes like 18.5 in hg at idle.
I opened the BOV and found that two springs were in there, I tested the BOV with the vacuum pump with each spring installed by itself. The larger spring started opening at 12 in hg, and was fully open at 17 in hg. The smaller spring started opening at 7 in hg, and was fully open at 11 in hg.
I installed just the larger spring, figuring it was just about right, and was able to get it to work without chattering -- now I get a nice whoosh and a little whistle, which is how this thing is supposed to sound. I also hooked up the reference signal port (the lower port) in the BOV to the IC outlet pipe (I t'd off where the wastegate signal is). This seems to help the BOV open a little faster (boost pushes up, vacuum sucks up).
I can't get up to the 16 psi boost that I had with the stock BOV. I can get like 13-14 psi now! If I increase the spring tension in the BOV with the adjustment screw, I get more boost, but the chatter comes back. I'm stuck! I lost like 30 hp!
My problem is that Greddy never heard of this, so they have no advice! Has anyone else had this problem/resolution? Am I missing something?
I just bought a set of intercooler pipes, so I have one that has the Greddy flange installed on it. I bolted everything up, and installed the stock BOV vacuum signal hose (from the intake) to the Greddy BOV. The bottom port on the BOV was left open (to atmosphere). Even with the adjustment screw FULLY out (well, it's still "in" so that it seals the vacuum, but its not increasing spring tension) the turbo chatters and the BOV barely opens! I used a vacuum pump to test when the Greddy BOV was opening, and it wasn't starting to open until like 17 in hg! It wasn't fully opened until like 25 in hg! My car makes like 18.5 in hg at idle.
I opened the BOV and found that two springs were in there, I tested the BOV with the vacuum pump with each spring installed by itself. The larger spring started opening at 12 in hg, and was fully open at 17 in hg. The smaller spring started opening at 7 in hg, and was fully open at 11 in hg.
I installed just the larger spring, figuring it was just about right, and was able to get it to work without chattering -- now I get a nice whoosh and a little whistle, which is how this thing is supposed to sound. I also hooked up the reference signal port (the lower port) in the BOV to the IC outlet pipe (I t'd off where the wastegate signal is). This seems to help the BOV open a little faster (boost pushes up, vacuum sucks up).
I can't get up to the 16 psi boost that I had with the stock BOV. I can get like 13-14 psi now! If I increase the spring tension in the BOV with the adjustment screw, I get more boost, but the chatter comes back. I'm stuck! I lost like 30 hp!
My problem is that Greddy never heard of this, so they have no advice! Has anyone else had this problem/resolution? Am I missing something?
