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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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Just noticed compressor byass valve starting to flutter.
I replaced my compressor BPV with a brand new one less then a year ago. Today I noticed that it was making a fluttering sound when I let off of the pedal after being under a nominal amount of boost. I forget what causes this phenomenon. Could someone help refresh my memory?
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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06-28-2010, 07:29 PM
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That Guy
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Compressor surge.
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Jon 1988 Granite Green 911 3.4L 2005 Arctic Silver 996 GT3 Past worth mentioning - 1987 924S, 1987 944, 1988 944T with 5.7L LS1 |
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06-28-2010, 07:56 PM
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On Boost
Join Date: Dec 2009
Location: Melbourne, AUS
Posts: 398
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In australia you put a 2.5" metal pipe about 6-7" long to your turbo intake with no airfilter and it's called a 'dose' (a high pitched flutter)
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86 952 GTX3076R, M-Tune, eBoost 2, CEP/JME cam, CEP head. |
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06-29-2010, 03:29 AM
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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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The question is, why am I just starting to hear it now? The only thing different is that I just installed a 4.75mm waste gate shim, about a week ago. I'm not noticing any sort of improvement after installing the shim.
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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06-29-2010, 05:53 AM
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On Boost
Join Date: Dec 2009
Location: Melbourne, AUS
Posts: 398
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your BOV/BPS may not be opening, check the vac line to it or it might be getting stuck? is it a cheap ebay one?
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86 952 GTX3076R, M-Tune, eBoost 2, CEP/JME cam, CEP head. |
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06-29-2010, 09:03 AM
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Super Moderator
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Quote:
if you're hearing this now, the BOV is probably damaged at this point.
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'89 turbo-s (2.7, wolf3d ems, garrett dbb turbo, tial 46mm, etc. fast!) |
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06-29-2010, 10:03 AM
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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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Problem fixed! I just now found and fixed it, so I haven't even started it up yet, but I'm convinced that it's fixed. What was strange, is that it would flutter after only like a lb of boost was created and then the gas pedal was let up on. Looking at the factory gauge, the fluttering would not begin until the needle was half way between .4 and 1. Today when I pulled the end of the plastic hard line, drew up some vacuum, and then stuck the line onto my tongue, it held the vacuum no problem, so I knew that the diaphragm was good. Then I started tracing the line back, looking for possible leaks, and found it. It appears that when I disconnected the floating CV's electrical connector, for purposes of testing, I must have accidentally pulled out the hard line coming off one of the T's in the rear, that goes to the front, feeding the damper and the BPV (BOV, as some call it). A apologize for even bringing up the subject, before I checked those things.
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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06-30-2010, 07:31 AM
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On Boost
Join Date: Dec 2009
Location: Melbourne, AUS
Posts: 398
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that's what forums are for
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86 952 GTX3076R, M-Tune, eBoost 2, CEP/JME cam, CEP head. |
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06-30-2010, 08:44 AM
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All Spooled Up
Join Date: May 2009
Location: Between NE and Central PA
Posts: 2,516
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I guess so, thanks. But there really is no excuse for being THAT lazy. I should have never brought it up until AFTER the fact (that I looked for, found, and fixed, the problem). It would have been better to say: "Here's what happens when this particular line is not connected...". Without vacuum on that line, my compressor must have been surging real hard.
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>gray 89 951S - K27/8, MAF, 3" intake, 3" exhaust w/separate waste pipe, 55# inj, late cam; >red 87 924S - chip, K&N, punched-out cat&muffler >black 80 924 - (sold) >maroon 77 924 - auto (sold) |
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06-30-2010, 09:36 AM
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