2G Can't get boost leak test to work

[howdeyjake]

After finally finding a piece of IC piping that wasn't even connected, I have now came to this problem with my boost leak. I can build like 13-15 lbs. of boost constantaly when WOT with my EVOIII 16g and SMIC, but when I was doing a boost leak test, I can't find another leak, infact, when I check the boost gauge in the car, it doesn't even move the slightest bit. I connect my dads huge air compressor pushing exactly 21.5 psi to this

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Where the very bottom of the plastic intake connects onto the turbocharger. I connect my boost leak tester to that piece right? I can't figure out what is up with this. Any help is very much appreciated.

Thanks,
Jake

 

[phunny]

did you make sure to pinch off the boost controller vaccum line. Because boost controllers have small holes in them to vent off pressure.

 

[kenamond]

First of all, you should update your profile. It doesn't have anything listed.

You should attach your tester to the compressor inlet. That's where the bottom of the assembly in your picture normally connects. Then you clamp it down tightly.

Do you have a mechanical boost gauge?

Do you have someone watching your boost gauge when you pressurize the intake during the test? If you have a bad leak, it can drop to zero before you can run around and look at your gauge if it's in the driver's compartment and not visible from the front of the car.

 

[TurboFever]

Where the very bottom of the plastic intake connects onto the turbocharger. I connect my boost leak tester to that piece right? I can't figure out what is up with this. Any help is very much appreciated.

Thanks,
Jake

Im not sure if I just read it wrong or what. But you dont connect the tester to your intake pipe. You can connect it to the turbo inlet .

 

[a_scobel]

Yep..connect the leak tester to the turbo itself. Put the amount of psi into the system equal to what boost you normally run..so if you're on the T25 around 15 psi of air should be fine.

 

[howdeyjake]

Like I said I am running a stock SMIC and piping, with a EVOIII big 16G turbo. When I pressurize the system, I told my mom to sit in my car and watch my aftermarket boost gauge that is on my A-Pillar arm thingy. I pressurize the system and it doesnt move at all. If I were to start up the car and drive away, it would show vac. and boost +-20 just fine. Yes I'm not that dumb to connect it to the black plastic intake tube, I was connecting it to the turbocharger inlet. I made sure the output of the air compressor was 21.5 psi(used a tire gauge). Anyone have any other clues? I don't hear any air leaking out anywere, even got out the soapy spraybotle and sprayed the IC piping down.
Keep the ideas coming!

Jake

 

[a_scobel]

Hmm I saw your other thread about the upper intercooler pipe connecting to the side-mount IC...are you sure that pipe is on there good?

Also a good site for you would be here. Instead of calling everything a 'box thing' or 'pipe thing' Click around!

 

[howdeyjake]

Yup. I checked all of the piping for anything that would cause a MAJOR leak, but it seems like that for the most part, everything is on tightly.

Anyone have any idea of what would cause this?

 

[kenamond]

I'm not positive on this, but if your boost gauge is an electrical gauge rather than mechanical, it might not function at all when unpowered. And the light inside the gauge doesn't mean it's an electrical gauge. In a mechanical gauge, the boost pressure physically moves the needle. An electrical gauge converts the pressure to an electrical signal which moves the needle.

Also, some have said that there is a small crank angle range where both intake and exhaust valves are open in atleast one cylinder (I imagine this means that there are four such crank angle ranges, one for each cylinder). You may have shut your motor down in one of these bad angles such that air is leaking through your cylinders and out your exhaust. They also said that you should be able to hear it leaking out of your exhaust. Tell your mom to put her ear to the tailpipes and listen for air, or maybe you can hear it in the exhaust mani. To fix this, you could either manually turn the motor over with a 1/2" breaker bar or turn the car over a bit with the ignition disabled. You might end up in the same situation as before, but it's very unlikely. I've done 20 or so leak tests on 4-5 different occasions and never had that happen.

Another thing you can do is pull your UICP hose (S-shaped with braided skin) off of your throttle body elbow and do your leak test there instead of your compressor inlet (clamp your tester to the TB elbow inlet). If one of your IC pipes is completely disconnected from the IC or other pipes, you wouldn't be able to build any pressure, but testing at the TB elbow would limit the test to your TB, IM, and cylinders rings, valve seats, valve shaft seals. If you can't get any boost signal (not even a wiggle) on your boost gauge in this test, it might be that your boost gauge only works when powered. I don't see how your car would run at all if these parts leaked badly enough to not register on a functioning boost gauge.

If that's the case, you might be able to turn the ignition to "ON" but not start the car and repeat the test so that the gauge is "on".

 

[howdeyjake]

Didn't even think that it may run off of electricity. Tomorrow I will check it again with my car in the "On" position. Thanks for all the help!!

Jake

 

[kenamond]

When you get a chance, update your mods in your profile.

 

[eboy0]

I'm having the same exact problem, I can't build pressure at the turbo inlet at all! I fixed all my leaks on the TB, and when I open the TB plate, and try to pressurize, I get 0 psi once again, and no hissing anywhere... does it escape that fast while my compressor is on?

 

[kenamond]

I'm having the same exact problem, I can't build pressure at the turbo inlet at all! I fixed all my leaks on the TB, and when I open the TB plate, and try to pressurize, I get 0 psi once again, and no hissing anywhere... does it escape that fast while my compressor is on?

First, you must have an aftermarket boost gauge. The stock gauge isn't actually a boost gauge, and the needle will not budge during a boost leak test.

If you have an aftermarket boost gauge and are doing a boost leak test, have someone monitor the gauge while you apply pressure so you don't have to run back to peek at it.

If you have bad boost leaks, it can drop down very quickly.

If you're applying pressure and it's not holding, try cranking your motor over 15* or more. It could be valve overlap. I forget the crank angle ranges where this occurs, so you might try searching for it. I'm vaguely recalling that there are four 15* ranges of crank angles where overlap could mess up a boost leak test, but I'm not sure, and it's different for the 1g vs 2g. Either oldman, Defiant or steve posted something about it as I recall.

Check all of the normal locations for leaks: PCV, TB gaskets, BISS (could've fallen out), TB shaft seals, couplers, IC pipes (holes), IC (holes), BOV and BOV flange, IM/head gasket, vaccuum lines, and injector seals. Could also be intake valve seals, but that's hard to tell apart from ring blowby if your compression is low. Make sure you seal off your MBC or BCS line coming off the compressor housing during a boost leak test, or it'll leak pressure through the bleeder in the MBC or BCS. If you're stumped, you can pull the UICP off the TB elbow and do the leak test on the TB elbow to see if the major leak is after the TB elbow or before.

Good luck!