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2009-2014 Cadillac CTS-V Performance Mods Discussion, P-valve Question in Cadillac CTS-V Series Forum - 2009-2014; Originally Posted by CadV Ok, so to make things simple....for us guys with pulley kits which will make more boost...all ...
  1. #46
    Gotham CTS-V's Avatar
    Gotham CTS-V is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    Quote Originally Posted by CadV View Post
    Ok, so to make things simple....for us guys with pulley kits which will make more boost...all we have to do is disconnect the X line and put something to cover where the X line would be? And what should we use to "cap" this X opening? I'd be scared to just put a piece of foam in there, although if that is what's recommended and is "safe" then cool.

    Thanks.

  2. #47
    jwa999 is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    Quote Originally Posted by Gotham CTS-V View Post
    Ok, so to make things simple....for us guys with pulley kits which will make more boost...all we have to do is disconnect the X line and put something to cover where the X line would be? And what should we use to "cap" this X opening? I'd be scared to just put a piece of foam in there, although if that is what's recommended and is "safe" then cool.

    Thanks.
    Actually, the O line goes to the P valve. I pulled out the O line. It just a rubber hose that is pushed on a plastic tube. I used some electric tape to close both ends. Might need to find some foam, the tape might not last.
    If you look closely, there is already a piece of foam on the unused tube left of the O.

    No adverse effects, did't see any boost gains, but my airbox is still limited.
    Perhaps the boost comes on a little quicker, it's hard to say.

    Hans.

  3. #48
    musclesbmf is offline Cadillac Owners Connoisseur
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    Re: P-valve Question

    Personally, I capped the "P" and left the "O" open and did not like the results. I thought boost was lower, so I put it all back to normal. There are 2 contradictory posts in this thread. One says to cap the "P" (the foam dosn't cap anything, it keeps debris out of the "O"), and the other post says cap the "X".

    So once again, does anyone know what they are talking about?

    Mark

  4. #49
    musclesbmf is offline Cadillac Owners Connoisseur
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    Re: P-valve Question

    Quote Originally Posted by The Tony Show View Post
    You must have missed the part where I said "provided better longevity or protection". I have no doubt that putting a bigger crank pulley, upping the boost and defeating the boost limitations and bleed off make the car more powerful. Anyone who thinks they aren't taking a huge risk though, is kidding themselves.

    I never said that they tune it for max performance- every carmaker sets the car up in the "sweet spot" between max performance and realistic durability. I've been modding cars for years, and the reality is simple: Every time you add power, you remove some of the margin for error in how bad things break if something goes wrong. Top Fuel engines sure make awesome power, but then they get torn down and rebuilt after one quarter mile pass.

    Things like overboost protection are there to keep you from shattering a piston if something causes a boost spike. Does defeating it make more power? Sure it does- just like headers and tunes. But just like headers and tunes, it becomes a lot easier for something to get damaged if something happens.

    I'm not trying to rain on anyone's parade, but based on a lot of the comments I'm reading here I think a lot of the posters on this forum are new to modding (not all, but some). They need to be aware of what exactly they're doing when they tinker with overboost protection.
    You are correct sir... I did miss your point, and I do agree that many posts lead me to believe this is the first car some have modded.
    Best rule of thumb: "You play, you pay."

    Mark

  5. #50
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    Re: P-valve Question

    I don't believe tape is going to work. Go to an auto parts store and they usually sell rubber end caps that come in a box of assorted sizes. I was told by Jesse to pull the line marked P at the valve and close off the nipple the line came off of. I believe you can also do it by closeing the O instead. The line goes to both O and P. Leave the line open. Cecil.........

  6. #51
    backup is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    The X port feeds pressure from the supercharger to the XO valve. O feeds from the valve to the P port on the actuator.

    X-->O-->P

    So whether you remove X, O, or P, the pressure signal is broken to the P port. Capping the P port itself might be advantageous as the V (vaccuum) port on the actuator will pull air thru the P port if left uncapped.

    I found the best results from removing the X line from the X port, as the O/P line remains connected to the XO valve and acts as a cap or seal on the P port.

    As everyone else has said, this seems to have a very minor effect, and it could be placebo. In my seat of the pants testing it feels more responsive, with faster boost build, but it is really hard to say if it is real.

    Guys, I have seen people jump on a custom engine and trans tune, pulley swap, headers, intake, etc, without touching internals (some of you here posting in this thread). If you think this extra .5lb of phantom boost might kill your motor, then don't do the mod!! Ask questions and consider all alternatives, but pulling one of these lines will not suddenly give you 15lbs of boost though.

  7. #52
    jwa999 is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    Quote Originally Posted by musclesbmf View Post
    Personally, I capped the "P" and left the "O" open and did not like the results. I thought boost was lower, so I put it all back to normal. There are 2 contradictory posts in this thread. One says to cap the "P" (the foam dosn't cap anything, it keeps debris out of the "O"), and the other post says cap the "X".

    So once again, does anyone know what they are talking about?

    Mark
    Well, from what it looks like X is an input and O is an output on the valve that they are both connected to.
    X comes from the upper supercharger body, most likely outputting pressure that is then switched to O by the valve if needed.
    The O goes to P on the bypass controller, and I guess if enough pressure is applied to P, the bypass controller will stop boost.

    So if X is disconnected, the supercharger would be blowing air through that hose if it's not blocked resulting is a small amount of air loss. If O is disconnected, then it would only be blowing air if the valve is open.

    I don't thing the P input cares if it's blocked or open. Once it's disconnected from the supercharger, it's 1 atmosphere and won't activate the bypass valve.

    Caveat: This is pure speculation, I could be completely wrong.....

    lol: I see backup got a response too. End result: close everything, just make sure X does not go to P?

    Hans.

  8. #53
    musclesbmf is offline Cadillac Owners Connoisseur
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    Re: P-valve Question

    TTT.
    For more clarity. I've checked the ZR1 forum on corvetteforum and could find nothing on this topic over there.

    Mark

  9. #54
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    Re: P-valve Question

    I wish there was an actual solution. It's crazy how some of us are unplugging certain lines, capping others, leaving everything disconnected, etc. Wish there was a way to find out exactly what the best configuration is.

  10. #55
    CadV is offline Cadillac Owners Connoisseur
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    Re: P-valve Question

    I tried everything on mine and saw no difference. This is of course when I was hooked up to the dyno and reading the AF.

  11. #56
    jwa999 is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    Quote Originally Posted by Gotham CTS-V View Post
    I wish there was an actual solution. It's crazy how some of us are unplugging certain lines, capping others, leaving everything disconnected, etc. Wish there was a way to find out exactly what the best configuration is.
    Since there's a valve connecting X to O controlled by the ECU, the best solution would be to change the parameters in the ECU when it opens that valve.

  12. #57
    musclesbmf is offline Cadillac Owners Connoisseur
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    Re: P-valve Question

    Sorry you got banned, seriously.
    But shouldn't your beef have been with American Racing Headers because it was their product that was giving you a CEL? It was nothing you installed from Jesse that was giving you the fault code. Unless I have totally forgotten what your original gripe was.

    bottom line is this.... high flow cats will trip the CEL. And now that O2 sims are not sold anymore, the only way to get around the CEL is through programming. There are many avenues for programming and Jesse is just one of them. He doesn't want to turn off the rear o2 sensors for fear of EPA lawsuit like caspers electronics had. Can't blame him for that. So take your car to a local dyno and have the local "expert" tune your car with HP Tuners or LSEdit and be done with it. The reason for the quotes is because there are not a lot of GREAT tuners around.

    Personally I wish I lived near W4M Performance, Quality Motorsports, or LG, or Lingenfelter, or VetteDoctors, or any of the like. Places like that have great tuners and can get the car spot on. But I still don't believe they have the knowledge of Jesse when it comes to these cars. He has 2 of them and drives them into the ground (quarter mile and track racing).

    Anyways, we digress again.... P-valve anyone?

    Mark

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    Re: P-valve Question

    Very interesting thread....

    I think I may have to do it tonight. Why not... the 9.5 is on the way anyway.

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    Domsz06 is offline Cadillac Owner
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    Re: P-valve Question

    Quote Originally Posted by CadV View Post
    I got some pictures but I need help with this as well.

    Here is a picture of the sensor (with the green x and o). x other end goes into the blower lid and would this be where the boost gauge gets its reading? o is the opposite end of the p port and I put foam on it after I capped the p port. I used foam because that's how GM had the unused port next to o.



    What about the other two ports (except x) on the sensor? Do we use foam allowing them to breathe or do we cap them?

    This is the p port with a vacuum cap (Thanks Robert for the vacuum cap) on it, is this right?



    Brent mentioned something about backing a screw out and will give ya a half pound of boost. Is the below picture the screw he is referring too?

    so is this the screw jesse refers to that keeps the boost from building? he mentioned in my dyno I was bleeding boost and need to make sure the screw is closed. Is it he screw to the right of the upside down l bracket?

  15. #60
    6speeder is offline Cadillac Owners Fanatic
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    Re: P-valve Question

    Quote Originally Posted by CadV View Post
    I got some pictures but I need help with this as well.

    Here is a picture of the sensor (with the green x and o). x other end goes into the blower lid and would this be where the boost gauge gets its reading? o is the opposite end of the p port and I put foam on it after I capped the p port. I used foam because that's how GM had the unused port next to o.



    What about the other two ports (except x) on the sensor? Do we use foam allowing them to breathe or do we cap them?



    This is the p port with a vacuum cap (Thanks Robert for the vacuum cap) on it, is this right?



    Brent mentioned something about backing a screw out and will give ya a half pound of boost. Is the below picture the screw he is referring too?

    I'm new to this discussion, but it seems to me you are messing with two different boost control systems. The sensor with the x and O ports is for overboost control and could be turned off with the tune. The screw you turn to eliminate boost bleed is the boost bypass system which keeps the supercharger from delivering boost all the time.

    Yes? No?

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