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]

https://secure.memca.com/ecodetuning/images/products/product_256.jpg

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

[phantom6294]

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.

Wouldn't the waste gate need to close in order to increase boost? Closing the waste gate forces more air over/through the exhaust turbine (and hence spin faster and hence more boost) versus being diverted out the waste gate, no? Thus, a 0% WG DC means the waste gate is fully open (default position) and 100% WG DC means the waste gate is fully closed.

If you look at his log, the WG DC spikes up initially, closing the waste gate and helping to build boost, but as is common on stock cars, it creates too much (though in this specific case, the boost hits only about 15PSIg) and as such, the WG DC drops significantly and thus opens the waste gate to ensure the boost doesn't head to the moon. Then, the WG DC increases slightly to ensure the boost is maintained. As the RPM increases, and exhaust flow increase, less WG DC is needed (and thus the waste gate doesn't need to be as closed) to maintain the same boost level and the WG DC works it way down.

[Sacrilicious]

it's the other way around, actually. WG DC 100% = exhaust gases 100% dumped into the turbo. the higher duty cycle, the more boost is generated. that initial spike you see is what the ECU uses to kick start the spooling on the turbo.

here's a log of a v103 beta map that i took:

http://img530.imageshack.us/img530/8667/wgdcpg3.png

[MS3 GT]

i found out my boost is leaking when reaching higher mphs.. so that mean eighter my vacuum is leaking or clamps isnt tight enough..??

[phantom6294]

it's the other way around, actually. WG DC 100% = exhaust gases 100% dumped into the turbo. the higher duty cycle, the more boost is generated. that initial spike you see is what the ECU uses to kick start the spooling on the turbo.

Um... that's what I said. The waste gate has to be closed to send the exhaust gases to the exhaust turbine.... 100% WG DC = waste gate fully closed. You originally said you found it odd the OP's waste gate wasn't opening as much as it should. An open waste gate means low(er) boost.

[Sacrilicious]

Um... that's what I said. The waste gate has to be closed to send the exhaust gases to the exhaust turbine.... 100% WG DC = waste gate fully closed. You originally said you found it odd the OP's waste gate wasn't opening as much as it should. An open waste gate means low(er) boost.

whoops...i keep forgetting it's reversed when referring to WG position and that "open" means it's dumping to exhaust. regardless, the WG DC should be higher at the upper rpms than his graph is showing. now, my car is obviously boosting more than stock in that map (16-18 psi), but the fact that his WG DC just falls flat on its face makes me wonder what is up.

[Sacrilicious]

i found out my boost is leaking when reaching higher mphs.. so that mean eighter my vacuum is leaking or clamps isnt tight enough..??

how high is "higher mphs"? the reason i ask is that it just doesn't quite make sense. are you trying to say that you think you're leaking at high boost and high rpm? how do you know you're leaking? do you have low boost? can we see a log or get a detailed description of what happens?

[phantom6294]

whoops...i keep forgetting it's reversed when referring to WG position and that "open" means it's dumping to exhaust. regardless, the WG DC should be higher at the upper rpms than his graph is showing. now, my car is obviously boosting more than stock in that map (16-18 psi), but the fact that his WG DC just falls flat on its face makes me wonder what is up.

Okay... I started questioning myself... lol

Well, my stock car does the same thing in this cold weather; boost definitely isn't getting/holding 15-16 PSI. I've tightened three of the four clamps post turbo (I can't quite get to the last one just before the throttle body) to no avail. I had a Forge BPV on for a while in case it was the stock BPV was leaking to no avail. It seems the colder it is, the less boost my car wants to make. I just continue to wonder if the ECU is lowering its boost target for extremely cold temps to reduce cylinder pressures???

I may head out later to run some errands and will do some boost logs to compare with the OP. Ambient temps are about 30F right now.

[Sacrilicious]

Okay... I started questioning myself... lol

Well, my stock car does the same thing in this cold weather; boost definitely isn't getting/holding 15-16 PSI. I've tightened three of the four clamps post turbo (I can't quite get to the last one just before the throttle body) to no avail. I had a Forge BPV on for a while in case it was the stock BPV was leaking to no avail. It seems the colder it is, the less boost my car wants to make. I just continue to wonder if the ECU is lowering its boost target for extremely cold temps to reduce cylinder pressures???

I may head out later to run some errands and will do some boost logs to compare with the OP. Ambient temps are about 30F right now.

lol...ya, don't mind me...i just had my head going in too many directions at the time and just didn't stop to word things right. how much boost are you making these days? i drove a whole winter last year with just a cobb sri, and i was making roughly the same boost throughout the winter...MAYBE 1psi short of the stock boost? what you say makes sense, though. i'm pretty damn sure the cooling efficiency of our IC system is a lot better with the ice cold air out. better cooling efficiency = bigger pressure drop across the IC core, which would account for lower boost levels. our car is load tuned, so it would not necessarily hyperventilate if our achieved boost level was 1-2 psi less than normal.

[Trader]

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.

LTFT

My LTFT's are usually about the following:

Idle = -1 to -3
Low RPM/low load = -1 to -3
Partial throttle = 0
WOT = 0

WGDC

The WGDC is confusing because a closed wastegate solenoid valve means an open wastegate (if and only if) boost is above the mechanical boost pressure of the wastegate actuator. On my old DSM it was about 10 psig. Dont know what it is on these MS3's?

So the solenoid is just a bleeder type valve that relieves pressure from the wastegate actuator keeping you under boost. So you should build boost to at least the actuator threshold (assume 10psi) then after that the solenoid valve has some meaning.... At that point the higher duty cycles correspond to more bleeding away of pressure from the actuator giving you boost.

Actual pedal position vs. Absolute throttle position sensor

Another thing I noticed is that I am at WOT (actual pedal position at 100%) while the Absolute throttle position sensor is registering 35% to 55%?

I have read that the ECU will adjust the "drive by wire" throttle. But doesn't this seem a bit much??

My thoughts

I am thinking that for some reason the ECU is doing this and it is probably not a leak. Still going to check for leaks though. I have read of some other threads about people getting lower boost when it is cold out. I am not seeing any WOT KR so the ecu is not adjusting due to that.

The problem is that there are not a lot of stock dashhawk logs out there to compare to. Most people seem to start logging after they have started modding. I got the DashHawk first on this car to understand how the ecu is working before I started modding, that way I can understand the effect of each mod.

I have not been able to do any more logs lately because of the snow here, but it is going to get a little warmer here in the next few days. I will do a comparison log to see if anything changes.

If nothing changes I may try resetting the ecu as well.

[phantom6294]

LTFT

My LTFT's are usually about the following:

Idle = -1 to -3
Low RPM/low load = -1 to -3
Partial throttle = 0
WOT = 0


Those look great to me. About what I see on my stock MS3 (okay, I do have an AWR 88d rear mount... but that has NOTHING to do with boost).


Actual pedal position vs. Absolute throttle position sensor

Another thing I noticed is that I am at WOT (actual pedal position at 100%) while the Absolute throttle position sensor is registering 35% to 55%?

I have read that the ECU will adjust the "drive by wire" throttle. But doesn't this seem a bit much??

This is normal. The ECU will allow the throttle to be fully or near fully open upon initial boost generation, but after that... it's rarely open much more than halfway. There's a lot of discussion about this.


The problem is that there are not a lot of stock dashhawk logs out there to compare to. Most people seem to start logging after they have started modding. I got the DashHawk first on this car to understand how the ecu is working before I started modding, that way I can understand the effect of each mod.

Ask... and ye shall receive. I went out and did some boosted runs to get some logs. As I said, my car is stock (except the mount). Here are some logs -- I am HAPPY to take screenshots at higher res, but figured I would keep the res down -- hopefully the logs are still legible.

4th Gear:
http://www.cademetz.com/ms3/4th_gear_01.png

5th Gear #1:
http://www.cademetz.com/ms3/5th_gear_01.png

5th Gear #2:
http://www.cademetz.com/ms3/5th_gear_02.png

http://www.cademetz.com/ms3/6th_gear_01.png


I realize that the higher gears don't go into higher RPM... but you'll understand I would prefer NOT to post logs showing my RPM and what gear, thereby admitting to insane speeds. I may... I may not have some logs with higher RPM runs and those logs, which may or may not exist, might show the boost continues to go down.

Also, realize that the TPS and WG DC are graphed against the same scale -- so, to get the reading for WG DC, look at the light purple numbers.

So, analysis? The fourth gear run shows an initial spike of ~16 PSIg and then it quickly falls off and by 4k RPM boost is below 13 PSIg. By ~4500 RPM, boost is ~12 PSIg and continue to fall.

First 5th gear run initially spikes to ~17 PSIg then quickly tapers and holds for just a moment at ~15.6 PSIg. After 3200 RPM the boost drops to ~13-14 PSIg range. The second 5th gear run is nearly identical.

Finally, 6th gear run initially looks great... however, notice I start the run at 2500RPM (whereas the rest started at 3000RPM) which is normally more load than I like to put on the engine... but I do this for science. At such a low RPM, the boost is maintained about 15.6 PSIg until about 3300RPM and then its downhill from there.

I would think... that if I had a significant boost leak, and the ECU were targeting a higher boost, the WG DC would be bouncing around and the boost would be bouncing around at the ECU tries to maintain that boost (e.g. 15.6 PSIg)

[Sacrilicious]

well, looks like you two are running roughly the same. looks like the car has severely detuned itself for the winter...=d

[Trader]

Yea that 4th gear log looks very similar response to my first log in 4th gear.

Both boost and AFR.

I will try some 5th gear logs as well soon.

[dread]

Wow no wonder my car always drove like shit in the winter. As far as you rel. throttle goes the max number is 74. You guys need to get tuned. It looks like the ecu is not allowing the throttle to open which is preventing boost from building.

[motomike239]

well after following this thread i can relate to the same problem, i installed my cpe-nano and now my car drives totally different as in its not nearly as responsive as before without the intake, i dont have a DH but it does seem like it doesnt hold boost for crap now :(