Boost leak test

[97gsxturbo97]

So I took my bone stock talon TSI AWD automatic to the track to see what it can do. I brake boosted to 12psi and launched perfectly but I kinda felt like i was being held back. I managed to do a 2.5 60ft and a 16.5 at 82mph in the 1/4 mile. Pathetic I know, I figured I did something wrong. So I go to install a cone filter from autozone, nothing special and find out that the stock airbox made a tiny hole in the stock plastic upper intercooler pipe. I figure thats my problem. I fix the hole, install the filter and go back to the track the following week.

I brake boost again at the line and launch and still feel like Im not taking off that fast. I managed a 16.9 at 83mph with a 2.8 60ft. What the heck? So then I figure mabye im pulling timing and brake boosting too long. So this time no brake boosting. The light turns green and I put it to the floor. Launch feels good, SLow but i thought i did alot better. To my surprise that was my worst run at 18.1 at 82 mph. The car is getting slower and slower so I leave.

I decide to do a boost leak test today. I pressurize up to 15 psi and it all imediately leaks out from the STOCK PLASTIC BOV, I then pressure to 10 psi and immediatley leaks out from the bov. I pressurize up to 5 psi and it all comes out the bov. If I put my hand over the bov it holds pressure. Now I know these leak around 11-12 psi but it seems like it wont hold anything. Im assuming this is my problem.

Now my question Am i running really lean or really rich because of this?

 

[rEclipserGST]

So I took my bone stock talon TSI AWD automatic to the track to see what it can do. I brake boosted to 12psi and launched perfectly but I kinda felt like i was being held back. I managed to do a 2.5 60ft and a 16.5 at 82mph in the 1/4 mile. Pathetic I know, I figured I did something wrong. So I go to install a cone filter from autozone, nothing special and find out that the stock airbox made a tiny hole in the stock plastic upper intercooler pipe. I figure thats my problem. I fix the hole, install the filter and go back to the track the following week.

I brake boost again at the line and launch and still feel like Im not taking off that fast. I managed a 16.9 at 83mph with a 2.8 60ft. What the heck? So then I figure mabye im pulling timing and brake boosting too long. So this time no brake boosting. The light turns green and I put it to the floor. Launch feels good, SLow but i thought i did alot better. To my surprise that was my worst run at 18.1 at 82 mph. The car is getting slower and slower so I leave.

I decide to do a boost leak test today. I pressurize up to 15 psi and it all imediately leaks out from the STOCK PLASTIC BOV, I then pressure to 10 psi and immediatley leaks out from the bov. I pressurize up to 5 psi and it all comes out the bov. If I put my hand over the bov it holds pressure. Now I know these leak around 11-12 psi but it seems like it wont hold anything. Im assuming this is my problem.

Now my question Am i running really lean or really rich because of this?

Rich I assume. Hard to tell with no logs or any other data. All you really have to do is buy a 2g adapter for a 1g bov. Buy a 1g bov, bolt it on. Boost leak test it, then hit the track again. I bet you do 100% better. I have a 1g bov with the 2g adapter on my car and lemme tell you, it makes a hell of a difference.

Buy a logger as well. They run about 100. Or you can use Evoscan with a laptop since you have a 97. Search harder.

 

[STEVEn95tsi]

Its hard to tell without any kind of information. Sounds like you need a new BOV. As he said^^^ 1g BOV with a 2g adapter is the a quick and simple fix. Or you can go ahead and pick up a used aftermarket BOV. But reguardless, you need a new BOV.

 

[97gsxturbo97]

Im picking up all new pipes and a new bov so that should fix my problem.

That only thing that Im wondering is that the valve is not open yet air still leaks out of the bov? Is that suppose to happen? I was expected to hear nothing until i hit atleast 10psi? Instead I can bring it up to 5psi and feel it all leak out?

These valves are suppose to leak becuase the stock spring cannot hold the valve shut. Well the valve is shut in my case and there is still air coming out so is my stock BOV defective?

 

[LiquidX]

Yes, you'll need a new BOV if it's leaking that bad. Hard piping is a good upgrade. Search the classifieds, I know of one person selling the greddy hard pipe kit .

 

[habitatguy187]

You need a new one anyway, but out of curiosity is the vacuum line attached that runs from the backside of the BOV to the intake manifold? If not that would explain why it leaks THAT easily.

 

[97gsxturbo97]

yes the vacuum line was attached

 

[97gsxturbo97]

So I did the boost leak test again only cause I havent done it too many times and wanted to make sure I am doing it right. So I pressurized the system and the most I can get the gauge up to is 13 psi which that makes sense because of the stock bov. Now it still imediately bleeds all the air out so I figured I would do a little test to confirm whats going on.

I put a rubber glove over the recirculation tube and clamped it down. I brought it up to 5psi and watched what happend. This only took 2-3 secs. Here is a video......

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[habitatguy187]

Can't see a thing.

 

[97gsxturbo97]

Sorry the camera is cheap but the first notch you see on the gauge is 5psi. The glove was completely delflated and by the time the camera was moved over it was blown up and you could see it getting bigger as the air bled out. Just stare at the blue glove and watch it. Is it pretty obvious that this shouldnt be happening. Please dont come back with an answer like the stock bov sucks, I am learning to find out what is and what is not suppose to happen in the future with other parts. Let say I did this to a 1g bov, would air still come out?

All this air is metered by the MAS yet not making it into the motor so the car is running insanely rich?

Wouldnt all this excess air dumping through the recirculating tube interrupt the compressor flow?

 

[habitatguy187]

Let say I did this to a 1g bov, would air still come out?

It shouldn't at 5psi, mine holds 20 but it's crushed.

All this air is metered by the MAS yet not making it into the motor so the car is running insanely rich?

You are correct.

Wouldnt all this excess air dumping through the recirculating tube interrupt the compressor flow?

No, actually the compressor probably opens it more by sucking so much air from this area.

 

[tjbiker031]

No if you put in a 1g bov it will fix your leak but i can guarantee you have more. the 2g bov is just a bigger leak.

 

[->PrOjEcTGS<-]

All this air is metered by the MAS yet not making it into the motor so the car is running insanely rich?

You are correct.

Not really... Initially, when the bov opens you might see a blip of richness. What you have to remember is as long as the bov dump tube is recirculated the air will be going back into the intake stream. If it gets dumped in after the maf then it's still metered, just not at the right time. Then it will get sucked in through the turbo and compressed again. The turbo can only suck in so much air and the air that gets recirced back into the intake is now some of that air. The rest of it will come through the maf, metered correctly. The air dumped by the bov has already been metered and is just sort of hiding out in limbo between the intake, turbo, IC and BOV the rest is being properly metered by the maf. That's why you might see the AFR go rich for a second and then go back to normal numbers. You'll might also see a lower lb/min with a BOV doing this. If the bov was not recirculated then I'd say "Yes" you'll run rich, but in this case, no.

My stock 1g bov did this to me and it took me a long time to figure it out. It would hold up to 20psi and then leak during a BLT. In action it would actually leak around 10psi. AFR looked the same after I fixed it. But I gained a lot of power!!