Replaced stock BPV with EVO 8 BPV now boost hits 20psi

[hellraisin']

I preformed a boost leak test on my 98 talon tsi awd. I found that my stock 2g plastic bpv started leaking at about 10psi. I replaced it today with a metal EVO 8 bpv which bolts right in and now the car hits 19-20 psi in the lower rpms but falls to a steady 14psi afterwards. It doesnt have an MBC that I can see. The car is stock other then a boost gauge and now an EVO 8 bpv.

The car freakin flys like mad but I think I can hear the stock T25 turbo giving all its got. Almost like a vibrating whistle sound in thr higher rpms at wot.

 

[Dsmkauai]

Boost spike is your exhaust stock? Also FYI it's bov (blow-off valve) not bpv hope it's just a error And that t25 won't last to long like that unless tuned. Also if your on stock fuel system watch out for fuel cut. Check the wastgate out could be bad and causing the issue. If all hooked up stock should only boost 14psi and not spike crazy like that.

 

[hellraisin']

Bypass valve as in recurulating and blow off valve as in venting to atmosphere. Thats the way ive always heard it said. Either way.

Why would that make it boost spike I wonder?

 

[Dsmkauai]

Gotcha we just use bov round here
Cuz it finally doesn't have a boost leak .

 

[hellraisin']

Gotcha. I'm new to DSMs and turbo cars so thanks for not letting me sound ignorant! Lol My whole car stock. Exhaust and everything.

 

[PlanZero]

Are you sure your boost gauge is accurate? It's highly unusual to spike to 20 psi on stock fuel system without fuel cut, and you will definitely know fuel cut when you feel it (feels like a misfire), and even 14psi is on the high end. Are you sure there's no MBC? There's also a free mod to your stock BCS that can give you an extra 1-2 psi that may have been done at some point.
And you are correct, a stock valve (1g, 2g, evo, etc.) Is technically a bypass valve. Most aftermarket pieces are blow off valves, because in other platforms they're usually vented to the atmosphere.

 

[hellraisin']

The boost gauge is supposedly of good quality I assume. VEI systems as I recall, I'll double check later this evening. Whether or not its installed correctly I don't know.

Never felt it fuel cut.

Im going to check closer for an MBC but it should be pretty noticeable. I really don't think it has one.

 

[jared98gst]

Every car is different with fuel cut, for instance stock car with pump (rewired) maxxin out 450s id hit fuel cut at 18-22 psi depending on air density on a eBay 16g, that t25 will go quick spiking to 20 especially with miles on it.

Gj scrapping that plastic bov, make sure all other leaks are found and enjoy that beast!
If you hit a brick wall you know you've gone to far

 

[hellraisin']

If this helpes, a video I took today. The cel was on then went off. I know that's something to take seriously.

You can kinda see the boost gauge on the lower left. Sorry for the shaking. Iowa roads suck.

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[hellraisin']

Before I added the EVO 8 BOV after preforming a boost leak test. Even crappier video. But it shows what it was like before.

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[bo0st]

Does it seem slow? My T25 seems to pull harder than that.

 

[hellraisin']

Does it seem slow? My T25 seems to pull harder than that.

I put the stock 2G bov back on today. Now it's back to building only about 12psi. It runs like it does in the second video I posted.

It does seem slow I guess. I've never ridden in or owned another DSM to compare it to.

 

[hellraisin']

Found out the vacuum line off the BCS that connects to the intake tube pre turbocharger was unplugged. I can't tell if the BCS has been modified or not. I suspect that it has as I can't see anything in the nipple.

I can't drive it because I found out the valve cover is cracked. I was wondering where the oil was coming from. Spent $100 and have a replacement valve cover on the way.

Also one of my new tires has a screw in the sidewall. I plugged it so it won't go flat but it looks like I'll have to buy another tire. Tire Rack didn't send me a warranty paper with my tires even though road hazard is supposedly free so it looks like I'm about to have to spend another $125+/- on a tire.

I found my oil cap was loose today. Went to tighten it and it never tightened. Metal piece and nut fell down into the engine. Luckily I was able to retrieve both and nothing appears to be damaged after extremely thorough examination.

I'm beginning to think this car is jinxed.

 

[bo0st]

Found out the vacuum line off the BCS that connects to the intake tube pre turbocharger was unplugged. I can't tell if the BCS has been modified or not. I suspect that it has as I can't see anything in the nipple.

I can't drive it because I found out the valve cover is cracked. I was wondering where the oil was coming from. Spent $100 and have a replacement valve cover on the way.

Also one of my new tires has a screw in the sidewall. I plugged it so it won't go flat but it looks like I'll have to buy another tire. Tire Rack didn't send me a warranty paper with my tires even though road hazard is supposedly free so it looks like I'm about to have to spend another $125+/- on a tire.

I found my oil cap was loose today. Went to tighten it and it never tightened. Metal piece and nut fell down into the engine. Luckily I was able to retrieve both and nothing appears to be damaged after extremely thorough examination.

I'm beginning to think this car is jinxed.

Sounds like a fun project.

 

[Dsmkauai]

Sounds like a typical DSM gahaha

 

[OGDSM1989]

Nah......its a typical DSM. Needs some love and care ......good save on the metal pieces. I would take care of the valve cover and tire, then just look into some basic maintenance ( trans , t-case and diff a good tune up maybe bleed out all the brake and clutch fluids,power steering fluid , thermostat, rad flush , oil change and filter ) and drive it the way it is for a bit, have fun dont go crazy on mods right now and just enjoy the car.

 

[hellraisin']

Trans is done, by the dealer as with the oil and all that jazz. T case I have left to do. Rear diff as well. Tune up is done except wires. I'm just trying to get the darn thing to run right.

I know my stock 2G BOV is leaking. Can't find any other boost leaks. When I eliminate that leak (by installing the EVO 8 BOV) I get boost spikes in the lower RPM range to around 19-21psi. Either that or the boost gauge I have is bad or installed incorrectly.

I'm going to keep messing with it until I figure it out and get it right.

 

[hellraisin']

Figured I'd post an update with the new Autometer mechanical boost gauge installed. I installed it where the previous one was as for the vacuum source. It's T'd into a vacuum line close to the brake master cylinder. I'm beginning to wonder if that may be an issue.

Here is a video to better describe the issue I'm having. The car isn't WOT in the video. I'd estimate that the accelerator is pushed 80% to the floor in the video. Everything about the boost reading seems abnormal to me but I've never owned a DSM before this and have nothing to compare it to. The car has the EVO 8 BPV installed.

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[Eurogaps]

check the wastegate vacuum line

check the vaccum solenoid

maybe yoy have a broken hose

 

[BoostinWonder_]

Have you tried replacing the wastegate? In the past I had to replace my 16g's wastegate when I was experiencing a similar issue.

Do you have a stock exhaust?

This might help you with your boost gauge installation:
http://www.vfaq.com./index-main.html

Stock boost pressure from a T-25 is around 10-15 psi, I believe.

Hope this helps.

 

[hellraisin']

check the wastegate vacuum line

check the vaccum solenoid

maybe yoy have a broken hose

I've looked at the wastegate vacuum line. Everything appears to be good. I'll check it more thoroughly.

I've preformed a boost leak test and didn't find any faulty vacuum line. But I may check again.

Have you tried replacing the wastegate? In the past I had to replace my 16g's wastegate when I was experiencing a similar issue.

Do you have a stock exhaust?

This might help you with your boost gauge installation:
http://www.vfaq.com./index-main.html

Stock boost pressure from a T-25 is around 10-15 psi, I believe.

Hope this helps.

I haven't replaced the wastegate. Stock exhaust. Thanks for the vfaq link.

My boost gauge is not installed in the correct location. The previous owner had an electronic boost gauge installed and upon replacing the gauge I used the same T fitting they had in place. Which I now know was installed in the wrong location.

It should be a max of 15psi from what I've read. I'll see if installing the vacuum line to the correct source does anything.

 

[Eurogaps]

are you made the correction?

 

[2gmitsueclipse]

From reading this, it sounds like the boost spike issue has always been there (masked by the 2g plastic bypass valve), or something changed when you installed the EVO bypass valve.

The max spike under normal conditions on a stock 2g should be around 15 psi (with restictor in BCS removed) and settle to about 13 psi.

As the OP is realizing, the boost gauge should be moved to an appropriate spot. Refer to the link below or vacuum line B in the diagram pictured below:

• http://www.roadraceengineering.com/instructions/vdoboostgaugeinstructions.htm

Additionally, the wastegate has been mentioned, but it does not seem to have been tested.

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Yours should open around the 10 psi range.

Ensure the stock BCS (wastegate sloenoid below) vacuum lines are routed correctly:

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[hellraisin']

are you made the correction?

Not yet. I had to order some new compression fitting sleeves and nylon line. The current line is cut too short to reach the proper location. The compression fitting sleeve was a little deformed on the back of the boost gauge. I have both now and will be doing it in the next few days.

From reading this, it sounds like the boost spike issue has always been there (masked by the 2g plastic bypass valve), or something changed when you installed the EVO bypass valve.

The max spike under normal conditions on a stock 2g should be around 15 psi (with restictor in BCS removed) and settle to about 13 psi.

As the OP is realizing, the boost gauge should be moved to an appropriate spot. Refer to the link below or vacuum line B in the diagram pictured below:

• http://www.roadraceengineering.com/instructions/vdoboostgaugeinstructions.htm

Additionally, the wastegate has been mentioned, but it does not seem to have been tested.

• You must be logged in to view this image or video.

Yours should open around the 10 psi range.

Ensure the stock BCS (wastegate sloenoid below) vacuum lines are routed correctly:

You must be logged in to view this image or video.

I would say you are correct as for the issue and the faulty 2G BPV masking it. I'm moving the line for the boost gauge to the right spot tomorrow probably. Awesome video on testing the wastegate. Thank you! Will check the vacuum lines and ensure they are routed correctly. Thanks for your help. This being my first turbo car I'm a little ignorant. I feel like I should have found some of the info you have given here during my searching... *sigh*


Oh, and I have another thread on here about a ticking sound that happens only when in boost and when cold. I'm sure it's turbo related and it didn't start until after running the EVO BPV and boost spiking to near 20 psi for a 10 or 15 min drive. Not to get off topic from the issue in this thread but I think maybe I've damaged the turbo with the boost spiking.

 

[Eurogaps]

ok

be in contac...I want to know if you resolve the problem...