Not your ordinary boost leak test question. Help me out

[kmoore]

Hey guys i got some questions concerning boost leak tests that i did. This might be kind of long so please hear me out and i could use any and all help.
About a week ago i got my uicp's and greddy type rs BOV from dejon. Well, i noticed that dejon gave me too big of a coupler (2 1/2") for my upper intercooler pipes so i called him up and asked if he could ship me the right one (2 1/4"). He said sure and he said he would ship me one right away. Well, i used the 2 1/2" uicp coupler for the time being until the right size one showed up. The 2 1/2" was a little big but i tightened it down really tight and made it work. So i got everything tightened down and did a boost leak test with the big coupler and the test showed that i had a boost leak by my throttle body. On my boost gauge during the test showed that i was pressurizing the system to 12 psi which was what i wanted. Got the leak fixed and took it out for a spin. It pulled really hard and i like both products a lot. Then, about 3 days later i got the right size coupler (2 1/4") from dejon. I put the right size coupler on and took the big coupler off. When i put the new coupler on i took off the pipe connected to the throttle body. I then did a boost leak test with the new coupler on and now i can't pressurize the system at all. I had my dad watch my boost gauge while i was trying to pressurize the system and he said that the needle didn't even move at all. I wanted to still see that the boost gauge was working, so i turned on the car and it IS still working. So it's not my boost gauge. So then, i purposely on bolted my BOV a little bit so that i could see if the pipes were getting pressurized. I did another boost leak test with the BOV un-bolted and air was coming out of the flange. So all the pipes up to my BOV are getting pressurized. I bolted the BOV back down and did another one and i noticed that air is coming out of my MAS (that big black box in between my filter and intake pipe). It is coming out of the smaller box inside of the MAS on the right side. Is air supposed to come out of there when doing a boost leak test? Should i block that off? Why can't i pressurize my entire system? What do you think is going on? Please help me out i could really use it. Thanks in advance and sorry for the long post.

 

[brute]

It sounds like you can't pressurize your whole system just because you have such a bad leak. You can try taking the air filter, MAS, and intake pipe COMPLETELY out, and hooking the boost leak tester right up to the compressor housing. Once it all pressurizes up, fix all the leaks and you should be good.

It doesn't really matter if the MAS is leaking under boost, because it never sees boost. From your compressor housing and after are the only parts that see boost.

 

[kmoore]

Thanks for the help but when i pressurize the system i can feel air coming out of that plug going into the MAS. I have triple checked that all my major pipes/hoses are connected (LICP, UICP, BOV, etc.) but i still can't pressurize the entire system. Thanks for you help. I appreciate it.

 

[UMR98GSX]

Always boost leak test from the compressor inlet since it is the beginning of the pressurized tract of the engine. Try it that way and then report back.

 

[kmoore]

That's what i have been doing. I just still don't understand why switching out the coupler and temporarily taking off the uicp that connects to the throttle body would cause me to not be able to pressurize my system. What do you guys think?

 

[UMR98GSX]

You mentioned earlier that you fixed a leak at the throttle body. Check to see that your throttle body gaskets are not leaking as well as the shaft seals in the throttle body. Changing to the correct sized coupler should not have any effect as long as you tightened it down well enough.

 

[burntheblobs]

I'm pretty sure if you test with all your valves open, the air will just go right through the engine and out the exhaust. Try making sure you're at TDC.

 

[kmoore]

What is TDC? And about the leak at the throttle body leak, that was before i replaced the coupler and removed the top uicp temporarily. Now with the pipe back on and the new coupler in, i can't even pressurize the system. So i can't even test to see if there are any leaks.

 

[kmoore]

Thanks for your guys help also.

 

[kmoore]

So does anybody know what TDC means? Can someone explain it to me?

 

[compression]

tdc is top dead center, make sure your timing is top dead center, because if its not, air can sneak through some open valves.

 

[kmoore]

Alright cool, thanks. So how do you think i should check to be completely sure?

 

[compression]

pop off your cam gear guard , you should see 2 little pins near the center of the cam gear, make sure both of them are facing straight upwards.

 

[AtomikRage45]

im having the same problem... i have been trying to use a air canister and i just cant get the boost gauge to move at all imma try with it at TDC tomorrow

 

[iceman21221]

make sure you check all your vacum lines. start at the intake manifold and check every line. Also the EGR valve gasket maybe leaking. Also while you are pumping air in the system spray a mixture of water and dish soap over any lines or gaskets from the turbo all the way to the intake manifold, then over all the vacum lines.

 

[oldman]

TDC is exactly where you don't want to be during a pressure test. #1 TDC = #4 valve overlap.

kmoore,

1. Please do not bump your threads.

2. Why is your mas/intake pipe still in the picture during pressure test? it should have been removed.

3. Did you disable your mbc during the test? Is your mbc hooked up to the BOV line.

4. Is your BOV vented.

I suspect that your intake pipe is still connected to the BOV recirculation tube,the brether on the VC, the leak you hear by the mas is probably coming from one or both of them.

 

[kmoore]

TDC is exactly where you don't want to be during a pressure test. #1 TDC = #4 valve overlap.

kmoore,

1. Please do not bump your threads.

2. Why is your mas/intake pipe still in the picture during pressure test? it should have been removed.

3. Did you disable your mbc during the test? Is your mbc hooked up to the BOV line.

4. Is your BOV vented.

I suspect that your intake pipe is still connected to the BOV recirculation tube,the brether on the VC, the leak you hear by the mas is probably coming from one or both of them.

First off, i don't understand when you say "bump yor threads" maybe you could pm and explain it to me? Second, my intake pipe is not connected to my turbo (Because i got to get to the turbo inlet to connect my boost leak tester). When i did my test i DID remove my MAS to do the test. But, when i did the test i noticed that air was comming out of that plug that plugs into the MAS (is this normal). Third, i do not have a MBC. And finally, no my BOV is NOT vented (Greddy type RS w/ recirculating piece). Thanks for the info

 

[oldman]

Be more specific about the "plug". In a stock formation, there are four things that plugs into the intake pipe, BOV return tube, BCS return hose, VC Breather return hose and the hose that goes to the canister, which one is leaking air?

 

[kmoore]

Ok, you know that black box that is in between your air filter and your intake pipe? I believe that it is called a MAS (Mas air sensor) i could be wrong. Well, there is a rectangle looking plug that is right by the BOV and plugs in there. When, i unplug that plug from the MAS or that black box in between my air filter and intake pipe, and when i do my test i feel air coming out of that plug.

 

[kmoore]

Also, when you say "TDC is exactly where you don't want to be during a pressure test." Did you mean to say "don't" or "do". Also, it said that i double posted my last post, but i don't see it on my screen. If i did i am sorry.

 

[oldman]

1. Do you mean the electrical plug? If so, is air coming out of the electrical plug on the mas side?

2. I'm assuming the intake pipe is off the turbo inlet but not removed from the car. If so, what else is still plugged into the intake pipe?

3. Do you still have the factory Boost Control Solenoid (BCS)?

 

[oldman]

Also, when you say "TDC is exactly where you don't want to be during a pressure test." Did you mean to say "don't" or "do".

"Don't". Members above were right about avoiding valve overlap (both intake and exhaust valves are open resulting in pressure air escaping right out of the exhaust) but they were wrong about how to avoid it. TDC (Top Dead Center) is exactly where valve overlaps occur, turning the crank to 30* after TDC will ensure no valve overlap. In any case, if you're not hearing air rushing out of your tailpipe, this is not of your concern.

Also, it said that i double posted my last post, but i don't see it on my screen. If i did i am sorry.

I have no idea what you're talking about.

 

[kmoore]

1. Do you mean the electrical plug? If so, is air coming out of the electrical plug on the mas side?

2. I'm assuming the intake pipe is off the turbo inlet but not removed from the car. If so, what else is still plugged into the intake pipe?

3. Do you still have the factory Boost Control Solenoid (BCS)?

1. Yes the electrical plug. And yes, air is coming out of there. The plug goes from the MAS to what looks like the fuse box.

2. Yes i removed the pipe from the car entirely. When the pipe and filter are connected i have 3 hoses plugged into it (The one from the BCS, The one coming from the valve cover, and coming from way down from what looks like underneath the car.

3. And yes i still have the factory Boost Control Solenoid

 

[oldman]

Then the air you hear coming out of the plug when the mas/filter was still connected was probably coming from the BCS or the breather hose, most likely both.

 

[kmoore]

Well, when i put my hand by the plug (while testing) i am positive it is coming from there. But, should i plug those hoses when i do my test?