Hey I have a question:I was curious to know where you guys tap off to get your boost readings and bov vacuum/pressure signal from..??On mine, since i have removed ALL my emission crap, i found 2 nipples (or whatever you guys wana call them) that look identical to the nipple that feeds the stock fuel pressure regulator. And its by chance that these 2 nipples are to the right of the one that feeds the fpr..I have one of those feeding my boost gauge and the other feeding the vacuum/pressure side of my bov.Is that good..?? Cause I have noticed that my bov is tripping open and close under partial throttle (causing bad hesitation) when my boost gauge starts to read boost... BUT only under partial throttle... in all gears, and really bad in 5th...
Basically, this is what it does. I hit the gas pedal anywhere from 10-20% and watch the boost gauge climb up from vacuum and once it gets to ZERO.... the bov trips open, then the motor will drop off, the bov closes, the motor will regain, and this process will continue until i either A: go more than 20% throttle or B: let of the throttle completely..!!And it does this VERY fast sounding like a machine gun under the hood... ONLY from 10-20% ish throttle in all gears..!!!I have yet to figure this problem out. The bov has been changed out, all vacuum feeds have been changed to new ones.... Im lost on this..
ThanksRobert
To the KA-T guys...
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:: orion ::
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The BOV can ONLY be referenced by the intake manifold. Doesn't matter where...those nipples, the PCV system nipples, T'eed off the FPR...doesn't matter.
And the boost gauge is best tapped off the intake IMO...
Sounds to me like compressor surge...as in the turbo is a bad match for your motor, like the spool is to the left of the surge line on the compressor map.
What turbo are you running...trim, A/R, etc...
If yours is an N-sport kit, DaveEEE is having similar issues, and we'll try to resolve them soon. We'll report back with anything definitive.
Let us know - Brian
And the boost gauge is best tapped off the intake IMO...
Sounds to me like compressor surge...as in the turbo is a bad match for your motor, like the spool is to the left of the surge line on the compressor map.
What turbo are you running...trim, A/R, etc...
If yours is an N-sport kit, DaveEEE is having similar issues, and we'll try to resolve them soon. We'll report back with anything definitive.
Let us know - Brian
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:: orion ::
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Structure240sx
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now i'm getting worried. mine has that same sound but i found a sound clip of a guy that put a ssqv on his lancer and it sounded exactly the same. and my turbo jsut blew the other day i figure for oil deprivation a while ago and progressivly getting worse since. my ssqv is adjusted as loose as it can be and it can be leaking under boost on the way that its designed supposively. btw this is on an nsport kit and i only hear the sound when i left off of the gas not at a constant 10-20% more like going from 20 down to 10% i might get it
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rn240sx
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Ive got the greddy type S bov mounted on the cold side. I have loosened it up all the way, tightened all the way, NO CHANGES..I have the bov top side (vacuum/pressure) fed from the manifold itself, the bottom side of the bov is fed pressure only and is tapped right there next to it. (basically i drilled a hole into the cold pipe about 2 inches away from the bov flange and welded a nipple to it, then ran a tiny hose from that nipple to the bottom side of the bov to help it open faster during shifts).I have the turbonetics T3/T04E 50 trim with .48 a/r on both sides.I do NOT have the revhard manifold anymore. I have a Tial 35mm wastegate with an 8 lb spring on it.
Its weird how this happens. As one of you said, it happens at HIGH rpm mainly at about 4k rpm (partial throttle ONLY) in ALL gears.>!!I have yet to figure out this problem.!!One guy from tampa told me this story on why this can be happening.
"While on partial throttle, the manifold is under vaccum state hence the bov reads vacuum...Once the rpm's start to rise, the turbo spools faster, then eventually the system will then become pressurized. But this pressure has to flow thru the ic pipes b4 it hits the manifold. Since the bov is b4 the manifold, it will be pushed open easy because its still reading vacuum from the manifold.. So when u push the pedal down, it drives the pressure into the manifold, thus pushing pressure into the bov to keep it closed..I hope i explained this clear enough, this guy from tampa explained this in a MUCH larger paragraph and it make lots of sense, but he didnt understand why this does not happen on his SR20...Any comments..??
Its weird how this happens. As one of you said, it happens at HIGH rpm mainly at about 4k rpm (partial throttle ONLY) in ALL gears.>!!I have yet to figure out this problem.!!One guy from tampa told me this story on why this can be happening.
"While on partial throttle, the manifold is under vaccum state hence the bov reads vacuum...Once the rpm's start to rise, the turbo spools faster, then eventually the system will then become pressurized. But this pressure has to flow thru the ic pipes b4 it hits the manifold. Since the bov is b4 the manifold, it will be pushed open easy because its still reading vacuum from the manifold.. So when u push the pedal down, it drives the pressure into the manifold, thus pushing pressure into the bov to keep it closed..I hope i explained this clear enough, this guy from tampa explained this in a MUCH larger paragraph and it make lots of sense, but he didnt understand why this does not happen on his SR20...Any comments..??
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canadians14
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rn240sx
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Trust me, if I had this in writing, I would have posted it..!! I got it from him about 3 months ago and i kept if for about 2 weeks, but then i deleted it cause nobody else had a cure nor explanation.I eventually dropped the subject, but now I am re-posting in hope that someone knows whats going on. This seems to be effecting several KA-T motors only....
I have a recirculated bypass valve that is dumped back into the turbo intake after the MAFS (which I think would cause it to run a bit lean since the MAFS isn't reading this air) I've never had a problem with this bypass valve (Turbo XS), but I can't hear the friggin' thing anymore ever since I ditched my cat, which isn't a bad thing because the noise got kind of annoying after a while--
See pic:http://www.eniety.com/pichost/pic/128-2895_IMG.JPG
Starting from the left side of the vacuum setup
Line that comes from underneath the intake manifold, which I hope is where my boost reading is coming from.
First "t"-line goes from here to a pressure switch that is activated at 6.75 psi to turn on the alcohol injection-- The white T that is further up in this line, to which the blue/black hose is attached runs to the right side of the car through the firewall and is where I get my boost-gauge reading from--
Second T on the right of that vacuum mess is attached to a hose that is attached to the top of my bypass valve--
Far right side of that T is connected to the OEM FPR.
On a side note--Do I need to worry about the vacuum line blowing off the FPR because this line now sees 10 psi of boost (it was previously disconnected when I had an aftermarket FPR)? The vacuum line didn't seem nearly as snug a fit as the other hoses even though the line was made for the FPR--I tie wrapped it just to make sure it'd stay on there (I don't have any hose clamps small enough for that hose), but I'm still wary of it possibly blowing off. All of the other lines I've never had a problem with.
See pic:http://www.eniety.com/pichost/pic/128-2895_IMG.JPG
Starting from the left side of the vacuum setup
Line that comes from underneath the intake manifold, which I hope is where my boost reading is coming from.
First "t"-line goes from here to a pressure switch that is activated at 6.75 psi to turn on the alcohol injection-- The white T that is further up in this line, to which the blue/black hose is attached runs to the right side of the car through the firewall and is where I get my boost-gauge reading from--
Second T on the right of that vacuum mess is attached to a hose that is attached to the top of my bypass valve--
Far right side of that T is connected to the OEM FPR.
On a side note--Do I need to worry about the vacuum line blowing off the FPR because this line now sees 10 psi of boost (it was previously disconnected when I had an aftermarket FPR)? The vacuum line didn't seem nearly as snug a fit as the other hoses even though the line was made for the FPR--I tie wrapped it just to make sure it'd stay on there (I don't have any hose clamps small enough for that hose), but I'm still wary of it possibly blowing off. All of the other lines I've never had a problem with.
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C-Kwik
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Robert, you run an open BOV do you knot? The pressure in the pipes could be opening the BOV and causing the mixture to go rich. This can cause a feeling of hesitation. I assume the car runs fine under a heavier throttle or WOT?It's normal for a BOV to open under low throttle conditions if it starts to build pressure in the I/C pipe.
If you must retain the Open BOV, you can always run a Dual system using a DV and a BOV. The DV would be recirculated so that it runs closed loop and keeps the ECU happy. The BOV would be set real tight so that it only opend when a large pressure differential is seen between the manifold and I/C pipes(pretty much when you close the throttle from at or near WOT). Consequently a proper DV remains open under vacuum and lets air around the compressor the other way and adds a little bit of power off boost.
If you must retain the Open BOV, you can always run a Dual system using a DV and a BOV. The DV would be recirculated so that it runs closed loop and keeps the ECU happy. The BOV would be set real tight so that it only opend when a large pressure differential is seen between the manifold and I/C pipes(pretty much when you close the throttle from at or near WOT). Consequently a proper DV remains open under vacuum and lets air around the compressor the other way and adds a little bit of power off boost.
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C-Kwik
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MarkEmark wrote:I have a recirculated bypass valve that is dumped back into the turbo intake after the MAFS (which I think would cause it to run a bit lean since the MAFS isn't reading this air) I've never had a problem with this bypass valve (Turbo XS), but I can't hear the friggin' thing anymore ever since I ditched my cat, which isn't a bad thing because the noise got kind of annoying after a while--
See pic:http://www.eniety.com/pichost/pic/128-2895_IMG.JPG
Starting from the left side of the vacuum setup
Line that comes from underneath the intake manifold, which I hope is where my boost reading is coming from.
First "t"-line goes from here to a pressure switch that is activated at 6.75 psi to turn on the alcohol injection-- The white T that is further up in this line, to which the blue/black hose is attached runs to the right side of the car through the firewall and is where I get my boost-gauge reading from--
Second T on the right of that vacuum mess is attached to a hose that is attached to the top of my bypass valve--
Far right side of that T is connected to the OEM FPR.
On a side note--Do I need to worry about the vacuum line blowing off the FPR because this line now sees 10 psi of boost (it was previously disconnected when I had an aftermarket FPR)? The vacuum line didn't seem nearly as snug a fit as the other hoses even though the line was made for the FPR--I tie wrapped it just to make sure it'd stay on there (I don't have any hose clamps small enough for that hose), but I'm still wary of it possibly blowing off. All of the other lines I've never had a problem with.
Mark, from what you describe, your BOV recirc is routed the way it should be. It should be putting the air back into the system somewhere between the MAF and the turbo, which is what you said.
As far as your hoses popping off, zipties will probably be the most you will need. Especially if the connections are barbed at all. It's a good idea to secure them, but consider they are less likely to pop off then I/C pipe couplers. The surface area to volume ratio is less with smaller pipes so less clamping force is needed. But again, I would at the least put zipties on them. the last thing you need is the wastegate line to pop off and cause overboost, or the FPR signal to pop off and cause a lean mixture when the FPR no longer compensates for boost, etc. But you certainly do not have to put as much into it as I/C pipe couplings.
C-Kwik wrote:Mark, from what you describe, your BOV recirc is routed the way it should be. It should be putting the air back into the system somewhere between the MAF and the turbo, which is what you said.
As far as your hoses popping off, zipties will probably be the most you will need. Especially if the connections are barbed at all. It's a good idea to secure them, but consider they are less likely to pop off then I/C pipe couplers. The surface area to volume ratio is less with smaller pipes so less clamping force is needed. But again, I would at the least put zipties on them. the last thing you need is the wastegate line to pop off and cause overboost, or the FPR signal to pop off and cause a lean mixture when the FPR no longer compensates for boost, etc. But you certainly do not have to put as much into it as I/C pipe couplings.
I'm glad I had everything connected the way it should be
I didn't know that intercooler coupling was more prone to blow off at the same pressure than vacuum hose--that's good to know. All of the lines are either hose-clamped or zip-tied; the main one I wasn't sure of was the vacuum "barb" on the OEM FPR, which actually isn't barbed at all--hose slid on pretty easily...but they're all zip tied anyhow.
I know all to well about the dangers of using crappy coupling/hose clamps...
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rn240sx
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TO C-Kwik:I've always run OPEN bov...Now im trying to figure HOW a recirculated bov will cure my problem.. The bov is gonna open regardless and if it does open, instead of it blowing to atmosphere, its gonna shoot it back to the turbo... which essentially im back to square one. I need to find out a way to keep this bov from opening under partial throttle..It sucks that I have to step on the gas pedal pretty hard to keep this bov from pre-maturly opening...
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C-Kwik
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Right, but with an open BOV, you are releasing air that the MAF thinks is going into the motor. The ECU will add fuel according to how much air the MAF sees. But if you release air into the atmosphere, the ECU will still inject the amount of fuel based on the amount of air that it thinks is going into the motor. But since not as much air is, the ECU injects too much fuel for the actual amount of air going in and you end up with a rich mixture.
With a recirculated BOV, the air should be routed back into the system behind the MAF. Since the air never leaves the system, only the amount of air the motor is actually taking into the combustion chambers will be passing through the MAF, so the ECU will inject the proper amount of fuel.
As far as keeping your BOV closed, I would hope that adjusting the pre-tension would take care of it, but it seems yours may not be working properly.
With a recirculated BOV, the air should be routed back into the system behind the MAF. Since the air never leaves the system, only the amount of air the motor is actually taking into the combustion chambers will be passing through the MAF, so the ECU will inject the proper amount of fuel.
As far as keeping your BOV closed, I would hope that adjusting the pre-tension would take care of it, but it seems yours may not be working properly.
