Stock BPV - How typical is it for leaking?

[Trader]

Thinking about getting the Forge BPV. My dashhawk is showing 16 psi at 3200 rpm down to about 10 to 12 psi at 6000 rpm (4th gear run).

Is it most peoples experience that the bpv is leaking causing the loss in boost and that a BPV will fix the issue?

Does anybody have a DH log that they can post showing the boost curve before and after the BPV?

 

[cjms3]

yeah it should fix this issue. alot of people have the same problem u do. low boost in high rpm's i just ordered my forge from protege =)

 

[Trader]

Attached is a data log in 4th gear. It was about 35 degrees when I recorded this.

I am completely stock.

My boost goes from about 15.5 psi to about 10 psi at 6000 rpm.

AFR drops from 12.5 to about 9.5.

Is it typical to run this rich?

And what kind of boost would I expect to hit in the upper rpms if I get a BPV ?

Thanks

 

[Sacrilicious]

can you do another log with your WG DC % logged as well? we need to see if your turbo is actually maxing itself out...it does look like you have SOME sort of leak in the system, though. it does not necessarily have to be the BPV, but if the BPV doesn't fully shut, then it would be able to create the problems you are seeing...unfortunately, the BPV isn't the only thing that can cause this...any sort of large leak in your intake track can cause this...=/

 

[Trader]

New log with WG%. It was about 15 degrees during this log. I let the car warm up fully though.

This show 3rd & 4th gear. I logged RPM, BOOST, actual throttle position, Abs TPS, & WG duty cycle %.

I know that the higher the WG duty cycle % the more boost you will build due to it bleading air from the actuator.

I am getting about 12 psi in 3rd gear and a spike to 15 psi in 4th and then it is pretty constant between 10.5 & 11.5 psi. The ECU seems to be controlling this by not bleading off air from the WG actuator like I would think it should.

Any thoughts?

 

[Sacrilicious]

ya, your WG DC looks awfully low...that would definitely explain why you're not boosting high enough. is that boost hose that leads to the WG tight? is it possible that it came loose?

 

[Trader]

Does anybody have any stock DH logs showing the wastegate duty cycle that I can compare to?

 

[phantom6294]

I thought my stock BPV was leaking as well, and got a Forge BPV and saw no change. I don't have any DH logs saved though before and after though. I didn't see quite as low boost numbers as you're showing but it wasn't what I would have expected. Same thing with the Wastegate as with your log... it wasn't maxing out so it seems like the ECU wasn't necessarily trying to hit 15.6 PSI. It would seem to make sense if the ECU was shoting for a higher boost number, it would max out the wastegate. For me, it seems the colder it gets, the less boost my car wants to make; especially when it gets so bitterly cold as its been lately (sub-freezing temps). I wonder if the air is cold enough and hence dense enough as to neccesitate lower boost to lower cylinder pressures? I'm no physics expert to know whether or not the air density changes enough though. Just a thought.

 

[LukeP]

tate lower boost to lower cylinder pressures? I'm no physics expert to know whether or not the air density changes enough though. Just a thought.

I believe it has something to do with this. Cold air is denser and would require less compression to get it to the same number of atmospheres as it would with warmer air. I think it would work out to roughly the same on the butt dyno.

 

[dread]

your car may make less boost in the cold because its pushing denser air and needs less boost to make the same targets. Trader your logs look horrible. What are your mods. Sac is right on your wastegate should not be closing like that and your boost should be higher on the stock tune. I would start looking for loose hoses. I doubt the problem is a leaky BPV since it is so extreme. Log your long term and short term fuel trims next.

 

[Trader]

I am stock, no mods at all.

 

[dread]

good, so you ltft's (long term fuel trims) should be close to zero if there is no leak. If you do have a leak your ltft's will be positive numbers indicating the ecu is adding fuel to compensate for the unmetered air that is getting somewhere. Check your intercooler hoses and anything that is after the turbo.

 

[phantom6294]

good, so you ltft's (long term fuel trims) should be close to zero if there is no leak. If you do have a leak your ltft's will be positive numbers indicating the ecu is adding fuel to compensate for the unmetered air that is getting somewhere. Check your intercooler hoses and anything that is after the turbo.

Um, if he had leak, post turbo, and under boost, wouldn't see negative numbers for his fuel trims? If air is leaking post turbo, the car would run rich, and the ECU would pull fuel (which is negative fuel trims, right?). If the leak were pre-turbo, and assumingly post-MAF, and under boost, he would run lean and the ECU would add fuel (which is positive fuel trims, right?). It would be in vacuum where a leak, regardless of location, would cause the ECU to add fuel (a positive fuel trims, right?)

 

[dread]

you might be right about the post turbo leak it depends if air is getting in or getting out. Either way if your fuel trims are negative or positive you probably have a leak somewhere. I would say if they are more they 8 off of zero you might have a leak.

 

[MS3 GT]

will boost automacally drop when reaching high mphs??

 

[dread]

no

 

[Sacrilicious]

the thing that concerns me is that the WG DC isn't even making the attempt to get your boost up to where it needs to be. i'll try to dig up one of my logs with the stock map, but this looks a lot like your WG isn't even attempting to open as much as it should.

 

[dread]

Yeah that doesn't look good. What could cause that sac? I would suggest taking your log to the dealership since you are stock.

 

[Sacrilicious]

well, that's why i was thinking that the hose leading to the WG wasn't perfectly tight. if that's the case, then it would make sense.

 

[Sacrilicious]

the hose connected to the fitting coming off of the WG (brass cylinder) is what i'm wondering about.