New to boost leak testing

[91Bomb]

Just built a boost leak tester and 1st time ever doing a test. Connected to turbo inlet but forgot and wasn't sure whether I'm supposed to have throttle plate open AND if I'm supposed to be doing anything with bov AND the hoses that goes from bov to the air duct from air cannister to turbo or those 2 other smaller hoses going to that air duct

Anyhow got 5 lbs boost on test and that's all I'm getting driving in 5th gear on highway brefore stuutering/breaking up of power until backing off the boost. I can boosst to 10 lbs in 1st, 2nd, 3rd before engine stuttering occurs badly too. Driving normal with modest boost car is perfect and so is idle. Can also drive at high speeds (80+) with no problems as long as I'm staying low on boost or none at all. Checked turbo and it spins freely and no shaft play or smoking anywhere (tailpipe included). Could not get more than 5-6 lbs on test and after shutting down air compressor boost drop was fast back to 0 and couldn't hear leak hissing anywhere. Am I doing boost test wrong and does my boost problem sound familiar? Car is bone stock and problem started after a few good full boost runs the other night.

 

[gofer]

Just built a boost leak tester and 1st time ever doing a test. Connected to turbo inlet but forgot and wasn't sure whether I'm supposed to have throttle plate open AND if I'm supposed to be doing anything with bov AND the hoses that goes from bov to the air duct from air cannister to turbo or those 2 other smaller hoses going to that air duct

Anyhow got 5 lbs boost on test and that's all I'm getting driving in 5th gear on highway brefore stuutering/breaking up of power until backing off the boost. I can boosst to 10 lbs in 1st, 2nd, 3rd before engine stuttering occurs badly too. Driving normal with modest boost car is perfect and so is idle. Can also drive at high speeds (80+) with no problems as long as I'm staying low on boost or none at all. Checked turbo and it spins freely and no shaft play or smoking anywhere (tailpipe included). Could not get more than 5-6 lbs on test and after shutting down air compressor boost drop was fast back to 0 and couldn't hear leak hissing anywhere. Am I doing boost test wrong and does my boost problem sound familiar? Car is bone stock and problem started after a few good full boost runs the other night.

it sounds to me like you can't hear where your boost leaks at because your air compressor is making so much noise. you for sure have a boost leak so you need to eliminate all that intercooler (IC) piping and start the test right at your throttle body elbow. if it holds 15 - 20psi then its good to go, then install your upper IC pipe and test from it, and so on and so on until everythings put back together.
since you can't hear the leak because your air compressor is making all kinds of noise grab a spray bottle and put water and soap in it and shake it up. then before you start your test spray everywhere air could leak out. (gaskets, bolts, bov, ic pipe connections, etc.) then when you do the test look for the soapy water to start bubbling... sometimes those stock rubber IC pipes can tear causing them to leak when you go into boost because they expand.

good luck! my guess is that you won't be able to hold past 14psi since your still using your stock 2g bov... let us know the results, im curious.

 

[Tanro]

You should be able to get the boost leak tester to 5 psi before tripping your compressor. Mine does. Hell I have taken a tire from like 11 psi to 35 without tripping the motor on my compressor.

It could be spark or fuel related and not boost leak related. I was having the exact issue you and changed my plugs with the correct gap, and new plug wires as well. Now it runs much better. I also had a boost leak around the pcv valve. I still haven't fixed that but I am running much better now.

 

[steve]

Make sure you engine isn't at TDC when your testing. At 30* ATDC you shouldn't have more than one set of valves per cylinder open.

It doesn't really matter if you hold the throttle open on not, air will flow through the FIAV, ISC, and BISS to pressurize the intake. Opening the throttle is just make it a fraction of a second quicker.

Gofer gave you some good tips.

 

[91Bomb]

I did turn air compressor off after it stopped building preesure at 5lbs and didn't hear anything. Connected to TB elbow and sprayed soapy water and seen nothng. Connected tester to turbo inlet and heard nothing


What about my stock 1g BOV? Should I test that separately?

 

[gofer]

I did turn air compressor off after it stopped building preesure at 5lbs and didn't hear anything. Connected to TB elbow and sprayed soapy water and seen nothng. Connected tester to turbo inlet and heard nothing


Plugs + wires are good.

id say to look elsewhere but only making 5psi on a BLT is 110% a boost leak somewhere...
you say you can only build 5psi doing the BLT at the turbo, how many psi are you holding at the TB elbow? does the car idle?

 

[91Bomb]

id say to look elsewhere but only making 5psi on a BLT is 110% a boost leak somewhere...
you say you can only build 5psi doing the BLT at the turbo, how many psi are you holding at the TB elbow? does the car idle?

Same 5lbs at TB elbow as turbo inlet. Car idles and drives great and can build close to 10lbs lbs in every gear before getting major stutering except in 5th gear which breaks up at 5 lbs. Can drive at 90 mph off boost and car is smooth as silk.

Anybody think BOV is bad?

 

[1twistdtalon]

I would double check your gap on your plugs, and make sure your wires and plugs are good. But you should be able to build more them 5psi when you boost leak test. Id say you have a very bad leak somewhere.

 

[steve]

But you should be able to build more them 5psi when you boost leak test. Id say you have a very bad leak somewhere.

Exactly, If you can only get to 5 psi there is something serious wrong. That means the turbo is working really hard pushing extra air trying to make some boost that isn't going into your cylinders. Unless your using a little tire inflater you should see higher pressure quickly and hear something leaking. Once you fix the major leaks the minor ones get harder to hear/find.

 

[91Bomb]

Yeah I only have a smaller tire inflator, not the tiny cheap ones but a bigger craftsman battery jump starter/ tire inflator

Anybody think the problem sounds like a bad BO V (stock 1g) because was thinking about testing that separately tomorrow. I'll have to try and get a cheap air tank because don't have the money to spend on a good air compressor.

 

[gofer]

Yeah I only have a smaller tire inflator, not the tiny cheap ones but a bigger craftsman battery jump starter/ tire inflator

Anybody think the problem sounds like a bad BO V (stock 1g) because was thinking about testing that separately tomorrow. I'll have to try and get a cheap air tank because don't have the money to spend on a good air compressor.

you may laugh but i parked at a shell gas station air compressor when my car started acting up and removed my intake. (i keep my BLT in the trunk) then i tossed in $.75 and pressurized it... sometimes if you flirt with the chick behind the counter she'll give you the 4 digit code for free air. then you can give your car a full BLT for free using a gas station air compressor.

 

[steve]

If you had the same result at the TB elbow then the BOV was out of the loop and couldn't be the cause.

 

[91Bomb]

you may laugh but i parked at a shell gas station air compressor when my car started acting up and removed my intake. (i keep my BLT in the trunk) then i tossed in $.75 and pressurized it... sometimes if you flirt with the chick behind the counter she'll give you the 4 digit code for free air. then you can give your car a full BLT for free using a gas station air compressor.

There's Shell station nearby but there's no girl there just an old man so flirting with him would be a little weird . Plus the air is free anway

 

[91Bomb]

Thinking about buying a 5 gallon air tank with no compressor and filled up that should be enough air to figure out this boost leak right?

 

[steve]

If you have little leaks, yes. It won't last long if you have anything big.

 

[91Bomb]

It is a big leak but hopefully I'll be able to locate it fast enough.