Can i get your opinion on my boost test

[twack]

Alright guys, when i do a boost leak test it wont hold anything at all. as fast as it goes in the air goes out no psi at all. Im hooking it up just at the throttle body so im not worried about the intercooler pipes. can anyone help me why its breathing so much

 

[twack]

Alright guys, when i do a boost leak test it wont hold anything at all. as fast as it goes in the air goes out no psi at all. Im hooking it up just at the throttle body so im not worried about the intercooler pipes. can anyone help me why its breathing so much. when im driving the car it does hold 20psi.

 

[xioca]

Where is your boost gauge tapped at, and can you hear it leaking from anywhere?

 

[twack]

Sounds like its just out the exhaust, no matter where the pistons are at.

 

[xveganxcowboyx]

Time to get out a bottle of soapy water. Spray your throttle body and injectors. Both are known to leak. Be sure to coat everything very well. The throttle body can leak a lot of air from a couple of spots. The injectors like to leak where they mate to the head. All can be fixed with new rubber. Cheap and easy.

And just to be sure, you should turn the engine over once to be sure you don't have any valve overlap.

 

[kmoore]

^^^^With the car put back together.
Do you hear any hissing at all? And deffinately do the soapy water trick if you hear some hissing.

 

[Dream On]

I would then do as suggested and check the pcv valve, tb gaskets, tb shaft seals, lower injector insulators, and your intake manifold gasket. I think these are the only places you could have leaks, outside of the couple vacuum lines running into the intake manifold.

 

[xveganxcowboyx]

I would then do as suggested and check the pcv valve, tb gaskets, tb shaft seals, lower injector insulators, and your intake manifold gasket. I think these are the only places you could have leaks, outside of the couple vacuum lines running into the intake manifold.

Good suggestions. I didn't think of the vacuum lines and somehow forgot the PCV. ALWAYS check the PCV. They are junk as often as not.

 

[kenamond]

First of all, make sure you boost leak test on a warmed-up motor. The rings will leak pretty bad on a cold motor even if you have good compression (not sure, but the intake valves might leak more when cold, too).

Try pulling the VC breather line off, repeat the boost test, and see if you have any massive leaks coming out there. If you have a bad PCV valve, bad intake valve seals, or bad compression, that could lead to leaks coming out the VC breather.

If you get a lot coming out the VC breather, pull the PCV valve first and test it (should seal up if you blow into the end where the hose connects). If it's bad, get an OEM valve; the Autozone/Carquest/etc. valves will not work (they look exactly the same and screw in, but they'll leak like mad right out of the box). Also, test the PCV valve at the dealer; some new OEM valves will leak, too.

If PCV valve seems okay, consider a compression test.

You may already know this, but it's worth mentioning: even with massive boost leaks, your turbo is very capable of overcoming these leaks and making 20psi. The problem is that the pressure at the compressor outlet may be 30psi. It's just that by the time it gets to your boost gauge, it's leaked down to 20psi. So you're overworking your turbo which isn't something you want to do. I'd keep on top of this until you figure out what's wrong - and then fix it .

Let us know if you find anything new out.

EDIT: Also, if you have a massive boost leak, you'll be running pig rich (you leak metered air, so the ECU adds too much fuel). It would be bad enough that you'd notice it easily with gas mileage (I was getting 8 miles/gallon with not-too-bad boost leaks!). If you are rich enough, you can see black smoke in your exhaust.

 

[oldman]

One thread per topic please, threads merged.

 

[PieEyedPiper]

I'm voting for improper engine alignment for the cause of your zero pressure boost leak test.

If you think you've fixed all your leaks and you still can't build pressure I vote to put the car in reverse (while boost leak testing, and of course engine off) and remove the top timing cover to see the cams. As your're trying to pressurize the intake nudge the car backwards a bit with your body, enough to turn the cams. You should eventually hit a sweet spot that will allow you to build pressure.
Good luck.

 

[kenamond]

I'm voting for improper engine alignment for the cause of your zero pressure boost leak test.

If you think you've fixed all your leaks and you still can't build pressure I vote to put the car in reverse (while boost leak testing, and of course engine off) and remove the top timing cover to see the cams. As your're trying to pressurize the intake nudge the car backwards a bit with your body, enough to turn the cams. You should eventually hit a sweet spot that will allow you to build pressure.
Good luck.

He said, "no matter where the pistons are at," which I took to mean that he tried different crank angles. Good idea though.