puzzling boost leak test results

[davidgt97]

Once again I am attempting to do a boost leak test in hope of finding why my car runs so poorly, especially above 4k. I have taken some time and tryed to read up on it a little but bear w/ me. I moved my mech. boost guage "t" to the fuel solenoid and my guage is out of the pillar and under the hood w/ me so I can see whats going on. I put my home-made tester (a 6" long piece of 2" pvc w/ a cap and a tire fitting threaded in the end) into the hose directly from the comp side of the turbo. I filled the line w/ 15psi and stopped to listen. The result worries me a little. The guage went from 15 to 5 rather quickly and I could hear it leaking. I repeated to find the leak was coming from the valve cover breather on the pass. side of the motor. What's going on?

 

[snowborder714]

Did you run the car a bit before performing the test? If not, your turbo seals have probably shrunk down a bit and are letting air passed. Run it for a bit, then do a test and see how bad it leaks.

Here's more info for you:
http://www.dsmtuners.com/forums/problem-diagnosis/285803-boost-leak-valve-cover-breather.html

But I can't imagine that the valve cover is your only leak if it dropped fairly quickly. Do the test again from the turbo and also from the upper intercooler pipe and use a good bit of soapy water that way you can 'see' your boost leaks.

 

[davidgt97]

I just drove around for about 20 min. and did the test again. It took 15 sec for the boost to go from 15psi to 10 psi. It took 25 sec for the boost to go from 15psi to 5 psi. It took 1:45 for 15 to 0. I sprayed down some previous leaks I fixed w/ soapy water: throttle body gaskets and seals, smic, and all the hose fittings. I also sprayed down the injector seals. So far I have found no leaks. I guess next I'll do the test right at the throttle body. Any ideas?

 

[davidgt97]

I just did the test again at the throttle body. Same results. So are you saying my issue is the pcv valve?

 

[snowborder714]

Well, that sounds better than it was before! I'd also pressurize the system to 20 psi, even if you only plan on running 15 psi.

Did you make sure to disconnect your MBC and plug the boost source vacuum line when doing the test?

And I bet you'll find a good bit of leaks when doing the test at the tb.

 

[snowborder714]

I just did the test again at the throttle body. Same results. So are you saying my issue is the pcv valve?

The vent on the valve cover is not your PCV valve. Your PCV valve comes out the firewall side of the valve cover.

See here:
http://members.shaw.ca/dsm.1000q/Engineprimer/1G/pcv.htm

Here's the whole engine bay, as it'll probably help you out in the future:
Virtual Tour of the DSM Engine Bay - 1G Visual Index

 

[davidgt97]

I went ahead and blocked off the pcv and did the test again. It was a little slower. I also found a small leak at the TB elbow. I took care of it. I also noticed that the car won't free rev past 5k so I think I have another problem since the car doesn't really make boost free revving.

 

[snowborder714]

You shouldn't block off the PCV. Hook the vacuum line back up to it and the intake manifold.

 

[davidgt97]

I already did. I didn't drive around w/ it blocked off I just blocked it to test the boost.