Hi Everyone,

I've added a 997TT to my stable and while I really do like the car, I've had a few headaches so far.

The biggest of which was that I had to put a new clutch in it immediately. (different story)

But whenever I get a car I like to try to get everything on the level. Oil change, checkup, boost test, etc. I'm Boost Leak testing and I have air (not a lot, but some) coming back out the intake (drivers side where the MAF is). I'm trying to figure out HOW this is possible. When you pressure test is the air supposed to be be tight? Not escaping at all? I sprayed soapy water on all the vacuum lines that I can see, all around the IPD plenum, at the ends fo the Y pipe, at ends of IC's and no leaks. Only thing that allows air to escape is this air coming BACK OUT the intake.

The only thing I can think of is that a check valve is not closing that lets air into the BRV and then that air is traveling up the intake hose. Does this make any sense?



Rundown on the car:
65mm VTG's
Agency Power BRV's (soon to be replaced with Evoms)
Evoms intake hoses
Evoms intercoolers
IPD Plenum

 

When doing a pressure test, you do need to cap off the openings of the system you're testing, which on a 997TT means blocking off both inlet pipes at the MAF sensor. Otherwise there's nothing stopping the air from flowing backwards out through the airbox, just as there should be nothing stopping air from being drawn in that way when the engine is running.

 

Ok, I had just plugged the pipes coming off the compressor wheel of both turbos. So you're saying that is not correct?

Driver Side:


Other side is plugged off similarly with a nozzle for my air connection.

This is where I hear/feel air coming out.

 

I've figured out that air is coming OUT the vacuum line attached to the driver side BRV.

So basically blowing back into the BRV. How would that happen?

 

Pictures explain a lot, you're testing correctly . Your diverter valves are probably leaking internally from a worn piston or o-rings, which can happen after a few years of use with that type of design. Boost will leak from the vacuum/pressure chamber through to the intake tract side, meaning the valve isn't opened or held shut when it should be. We recently redesigned our BRV solution to utilize the maintenance-free OEM piston and diaphragm along with a billet cap and a stiffer spring to prevent this: http://www.evoms.com/product_p/eng997ttbrv2.0.htm.

 

I actually ordered the parts you suggested earlier, but I'm now seeing that you utilize the OEM valve, which I don't have because I have this Agency Power part.

I'm going to post a video to show what is happening. Air is coming DOWN the vacuum line into the BRV. From my understanding air shouldn't move that direction at all in the system.

 

Kinda of topic but could u share specs of your pressure tester? Homemade with pvc parts or did u purchase from a vendor?

 

It's just two PVC 2.25" plugs. Drilled a hole on one and actually used a lighter to soften up the plastic. Then pushed a valve stem into it. They take about 15 minutes to make.

 

Thanks to a phone call with Sam at EVOMS I think I've figured out that the problem is a faulty Agency Power BRV. He has send me some OEM units and we'll see if this fixes the problem.

 

That is great service! + Rep Sam. And because you have the same name! I have seen this before with those BRVs. Are you getting surging on acceleration?

 

Sam, I've had some weird issues. Car just hasn't felt right since I got it. (About a month ago).

I went to the track and while I'm not a Great driver, my best trap speed was 122. I think I should be over that.

I just put a ERP Triple disk clutch in, and EPL tuned the car. So I feel like it should be stronger than that. Hopefully this BRV fixes the problem.

 

Well, I plugged the BRV lines and pressure tested and air is still escaping somewhere.

It sounds like it is way down deep. For example, I removed the oil fill cap and I can hear air somewhere deep in the system escaping. Doesn't sound like a little vacuum line or anything like that.

 

Check valves

 

You saying check the BRV valves, or it's a check valve somewhere up on top?

 

There are a few and off the plenum also that stop boost from going into the oil tank. Can you lower the motor a bit and use soapy water while under pressure? I'll text you some pics