Boost Creep (not a usual BS thread)
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Evolving Member
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From: Long Island, NY
thanks for the lengthy response dude.
The Hallman MBC, like most other bc's, comes with a small bleed hole -- through my experience with all of my turbo cars, I've never had to add a restriction to my boost line or increased the size of my bleed hole.
I've checked my whole system, without a doubt, there's no leaks. I've swapped out the boost controller for another, and the results didn't change at all. At this point, it's got to be the WGA. If anyone has a spare stock or aftermarket one and wants to send it to me, i'll throw it on. If it works, I'll buy a new one for you
The Hallman MBC, like most other bc's, comes with a small bleed hole -- through my experience with all of my turbo cars, I've never had to add a restriction to my boost line or increased the size of my bleed hole.
I've checked my whole system, without a doubt, there's no leaks. I've swapped out the boost controller for another, and the results didn't change at all. At this point, it's got to be the WGA. If anyone has a spare stock or aftermarket one and wants to send it to me, i'll throw it on. If it works, I'll buy a new one for you
Are you using all new boost lines from the turbo to the MBC and MBC to the WGA? If there are any restrictors in the line it may be reducing the signal so much that the WGA isn't getting enough signal to move properly. You could try and reduce the bleed hole size slightly with some duct tape temporarily as a test after you verify the lines are 100% flowing with no hidden restrictors. After that indeed I would swap that WGA and see what happens.
Let us know!
Let us know!
Some food for thought:
I've seen creep induced like this when you have a WGA cranked down with too much preload. Basically your base boost would be higher that way but the amount of travel restricts how much flow can get out that passage. The typical opening angle of the WG flapper is also restricting quite a bit of flow if you compare it to just an opening with no flapper. You did mention you turned down the boost to ~15 psi and that it only creeped a few psi which means that something is wacked with either the WGA or boost control setup you have. I would verify you have a full (and strong) boost signal reaching the MBC and that you don't have restrictors limiting the flow of pressure to the MBC, which may be too weak to move the WGA open. Also make sure the MBC is flowing the correct direction as all kinds of issues can occur if hooked up backwards! I'm not sure if you have a small bleed hole in the line after the MBC but before the WGA, but make sure it's not TOO big as that will weaken the signal and let the WG shut again with no control.
To find the minimum boost level that your physical WG passage & O2 housing can flow you could just run a boost source directly to the WGA and test at what RPM you start creeping and what the max psi reached was. Use a fresh line with no holes or restrictors in it so that the test is a valid snapshot of what your minimum boost actually is. Likely you will hit ~13-15 psi at lower RPM's but at some point it will creep in the mid to upper RPM's. If that ends up being 20 psi then you should be able to set boost for 20-25 psi with 1-2 psi spike at most and have it hold steady until you reach the flow limits of the turbo and then taper at higher RPM's.
Increasing the flow through the bypass side of the O2 housing may help but your description of having boost rocket up to 20 psi and then creep up to 25+ slowly is a warning sign that the signal to the WGA is the issue, or possibly the WGA itself. I've used the Forge WGA with a full signal line and MBC and had excellent boost control results on my Evo X, just make sure the bleed hole is just big enough to relieve pressure buildup in the line. The higher you are trying to raise it above the WGA's natural opening pressure the larger the hole, just start smaller and slowly increase. Going too small (or no bleed hole) will actually keep your WGA open with trapped boost pressure between shifts and you will feel the lack of spool.
Now I use an ATP O2 DP that has a Tial 44mm WG so my boost control is even more stable, but I mainly went that route because my internal WG failed due to a design issue with the Evo X GT30 turbos.
Hope that helps!
I've seen creep induced like this when you have a WGA cranked down with too much preload. Basically your base boost would be higher that way but the amount of travel restricts how much flow can get out that passage. The typical opening angle of the WG flapper is also restricting quite a bit of flow if you compare it to just an opening with no flapper. You did mention you turned down the boost to ~15 psi and that it only creeped a few psi which means that something is wacked with either the WGA or boost control setup you have. I would verify you have a full (and strong) boost signal reaching the MBC and that you don't have restrictors limiting the flow of pressure to the MBC, which may be too weak to move the WGA open. Also make sure the MBC is flowing the correct direction as all kinds of issues can occur if hooked up backwards! I'm not sure if you have a small bleed hole in the line after the MBC but before the WGA, but make sure it's not TOO big as that will weaken the signal and let the WG shut again with no control.
To find the minimum boost level that your physical WG passage & O2 housing can flow you could just run a boost source directly to the WGA and test at what RPM you start creeping and what the max psi reached was. Use a fresh line with no holes or restrictors in it so that the test is a valid snapshot of what your minimum boost actually is. Likely you will hit ~13-15 psi at lower RPM's but at some point it will creep in the mid to upper RPM's. If that ends up being 20 psi then you should be able to set boost for 20-25 psi with 1-2 psi spike at most and have it hold steady until you reach the flow limits of the turbo and then taper at higher RPM's.
Increasing the flow through the bypass side of the O2 housing may help but your description of having boost rocket up to 20 psi and then creep up to 25+ slowly is a warning sign that the signal to the WGA is the issue, or possibly the WGA itself. I've used the Forge WGA with a full signal line and MBC and had excellent boost control results on my Evo X, just make sure the bleed hole is just big enough to relieve pressure buildup in the line. The higher you are trying to raise it above the WGA's natural opening pressure the larger the hole, just start smaller and slowly increase. Going too small (or no bleed hole) will actually keep your WGA open with trapped boost pressure between shifts and you will feel the lack of spool.
Now I use an ATP O2 DP that has a Tial 44mm WG so my boost control is even more stable, but I mainly went that route because my internal WG failed due to a design issue with the Evo X GT30 turbos.
Hope that helps!
I swapped my stock wga lastnight and still noticed the same issue, however, i switched my siganl hose from the jpipe to the bov, and saw a lil improvment, but that maybe due to the bend in the signal line since it was doing a "u" going from the jpipe to the wga. it leads me to thinking that the id on the hose might be playing a big role in this. will report back on this tonight!
Sorry about bumping an old thread but I seem to be having the same issue as you berns. I thought i had resolved it before by changing the offset on my HKS EVC 5 but apparently it didn't. I'm pretty sure the EVC is fine and doing its job.
I too have a stock O2 housing with intake and exhaust; however no tune. My boost levels are around 19 to 20psi usually but today when I floored my car in 4th and 5th (two separate pulls) I boosted fine (hitting 19 to 20psi around 3k to 4k rpm and holding fine) out of no where my boost started to climb (hitting 20.5 by 5k rpm then 23psi by 7k rpm). I can't seem to figure it out.
Have you found any resolution as of late?
I too have a stock O2 housing with intake and exhaust; however no tune. My boost levels are around 19 to 20psi usually but today when I floored my car in 4th and 5th (two separate pulls) I boosted fine (hitting 19 to 20psi around 3k to 4k rpm and holding fine) out of no where my boost started to climb (hitting 20.5 by 5k rpm then 23psi by 7k rpm). I can't seem to figure it out.
Have you found any resolution as of late?
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From: Long Island, NY
my car is still the same, and the issue still seems more severe than what most people are experiencing.
I work a lot and just haven't cared enough to really dig into it. I imagine it's the wga, there's really no other possibility at this point. I just turned my mbc down to the point where I can go WOT in 6th gear and not boost more than 26psi, which basically means, at WOT running through the gears to redline, I'm really hitting around 21psi and tapering down from there, meaning, where my boost is when I shift at redline to the next gear etc...
I work a lot and just haven't cared enough to really dig into it. I imagine it's the wga, there's really no other possibility at this point. I just turned my mbc down to the point where I can go WOT in 6th gear and not boost more than 26psi, which basically means, at WOT running through the gears to redline, I'm really hitting around 21psi and tapering down from there, meaning, where my boost is when I shift at redline to the next gear etc...
my car is still the same, and the issue still seems more severe than what most people are experiencing.
I work a lot and just haven't cared enough to really dig into it. I imagine it's the wga, there's really no other possibility at this point. I just turned my mbc down to the point where I can go WOT in 6th gear and not boost more than 26psi, which basically means, at WOT running through the gears to redline, I'm really hitting around 21psi and tapering down from there, meaning, where my boost is when I shift at redline to the next gear etc...
I work a lot and just haven't cared enough to really dig into it. I imagine it's the wga, there's really no other possibility at this point. I just turned my mbc down to the point where I can go WOT in 6th gear and not boost more than 26psi, which basically means, at WOT running through the gears to redline, I'm really hitting around 21psi and tapering down from there, meaning, where my boost is when I shift at redline to the next gear etc...
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Evolving Member
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From: Long Island, NY
it's a consistent problem.
floor it in 3rd gear from 2000rpm, start boosting, hit 22psi, gradually increase to around 26, then taper around 7000... That's how it goes in any gear for the most part. I can't just hit 25psi and taper from there, like I'd like to.
floor it in 3rd gear from 2000rpm, start boosting, hit 22psi, gradually increase to around 26, then taper around 7000... That's how it goes in any gear for the most part. I can't just hit 25psi and taper from there, like I'd like to.
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Joined: Aug 2009
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From: Dayton, OH
Having the same issue here. It just started for me when I replaced my cat with a test pipe. I ran a full 3 inch exhaust with a larger o2 pipe and greddy boost controllor for months and was able to control boost fine. As soon as I put on the test pipe my boost is out of control. Shoots up to 20 psi and creeps to 24 to 25 if I let it. Its does this with my boost controller on and off. I have no control over my boost no matter what I set my boost controller to. Tmrw ill be checking all my connections but I didn't see anything wrong today. Do I just need to adjust my wastegate?
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