Hey guys, probably a stupid question, but you never know until you ask. My car runs great at 20PSI on 93 octane with the EVOIII16G. Having said that, when I did a boost leak test I may have found something, but I'm not sure. My steps:

1) Unplug intake pipe from turbo
2) Put on tester
3) Unplug UICP from throttlebody
4) Plug end of UICP
5) Fill with air to 25PSI
6) No leaks found

However, if I do this:

1) Unplug intake pipe from turbo
2) Put on tester
3) Fill with air
4) ???

On step 4 I lose a lot of air somewhere around the intake manifold. I'm talking fast, like my 6HP compressor primed to 120PSI can't keep boost above like 15PSI. I don't hear the normal "high pitch" of a hole in pipe etc, but more like a lot of air passing through a hole. Could it be because I don't have an EGR blockoff plate? Or does air go past the valves? Keep in mind, the car "seems" to run fine. As a side not, I also don't hear any leak from my stock 1G BOV at the first test.

Thanks!

Well you do have a boost leak, now you must pinpoint where it is, Do the test again but this time spray some soapy water around the area that you can hear the leak from. Where you get bubbles is where your leak is. A couple spots are the injector seals and the throttle body gasket. It could even be the intake manifold gasket giving up. Also if you have your emissions intake nipples blocked off then it could be leaking around those, ziptie those suckers down.

I had tried that before, but couldn't pinpoint it. I will try again and see what I find. Just seems that a leak that big the car wouldn't run at all. Thanks for the help.

No problem, try using a little more soap in your solution to get more bubbles, could help, also it could be a leak from the intake manifold gasket, since you can't actually see that and get to it with soapy water.

I can actually hear the leak up near the back of the motor, like where the throttle body meets the intake manifold. I guess it could be echoing somehow though.

Fmstrat said:

However, if I do this:
1) Unplug intake pipe from turbo
2) Put on tester
3) Fill with air
4) ???

Click to expand...

Alright, do your test again, but this time remove your oil cap.
If you hear a ton of air entering the Valve Cover, chances are your PCV is stuck open and allowing boost to enter the VC.

Disconnect your PCV from your IM.
Plug the port on the IM and retest.

Check all vacuum lines in the engine bay.
Zip tie them if necessary.
Hope this helps...

Thanks for the tip! I'll be giving this a shot this weekend, and I'll post the results.

Try putting your leak tester on your throttle body elbow. Since you didn't find any in the piping, try and do it there. Check around your injectors and gaskets and listen. Good luck.

Try checking the BAS screw that is on the throttle body. I heard my leak in the same place as you and put some soap and water and see if its leaking from there.

Dream On and 2nd gen GSX both have great tips.
But none of these tips are worth a damn if you don't use soapy water to track down those damn boost leaks.

Some leaks are so sublte that you can't hear them, but you can sure as hell see the bubbles form, you follow....

Chances are if you have high mileage, and if they've never been changed before, your injector seals are probably plastic by now instead of rubber.

Oh, and if your PCV is jacked up, just pay an extra few dollars and buy an OEM PCV.

Yea, I know there is none in the piping because the 30PSI test stayed in the piping at 30PSI for a long time. I left it and went inside and when I came back it was still there. Just need to get to the point with the whole intake. As for injector seals, I put in the 650's about 4 months ago and all the seals were replaced, so I doubt that's an issue, but the soap will let me know.

One other thing, a step I missed writing out. The vacumm hose that goes from the intake manifold to the BOV, and T's off to the MBC, I blocked that after the BOV. If it was left open, the BOV would actually leak air out of it. I assume that's normal since the BOV would have the pressure from the intake manifold on it during normal operation. I probably still need to get a new BOV though since I'm running 20PSI on the stock 1G BOV.

Thanks again!

Yeah, 1g BOV's leak after about 17 psi. You could upgrade, or do the Dodge garage mod. http://www.thedodgegarage.com/turbo_bov_mod.html

I read that a couple days ago and was thinking about it. But how do I test to make sure the BOV works at that pressure? With the top port plugged off between the BOV and the MBC, the 1G BOV doesn't leak as is. Am I not supposed to have to plug there? If I don't it leaks like crazy.

Fmstrat said:

I read that a couple days ago and was thinking about it. But how do I test to make sure the BOV works at that pressure? With the top port plugged off between the BOV and the MBC, the 1G BOV doesn't leak as is. Am I not supposed to have to plug there? If I don't it leaks like crazy.

Click to expand...

I'm not understanding you, what did you plug exactly?

There is a T in a vacuum line. One end goes to the intake manifold. One end goes to the BOV. One end goes to the MBC. Then the other side of the MBC goes to the wastegate controller. If I leave all this connected, air leaks out of the big hole in the BOV. If I stick some vice grips on the rubber hose between the MBC and the T, no air leaks.

Mine leaks in the same area as yours does.

I have mine narrowed down the the throttle body shaft seal, you might want to check there.

Fmstrat said:

There is a T in a vacuum line. One end goes to the intake manifold. One end goes to the BOV. One end goes to the MBC. Then the other side of the MBC goes to the wastegate controller. If I leave all this connected, air leaks out of the big hole in the BOV. If I stick some vice grips on the rubber hose between the MBC and the T, no air leaks.

Click to expand...

1. The BOV requires equal pressure on both sides, uicp and vacuum line, to seal properly.

2. Which mbc do you have? TurboXS? Please complete your profile damn it. Step one in leak testing is to disconnect the mbc because pressure will leak through the wastegate pressure relief hole on a ball and spring type mbc, the situation gets worse with a bleeder type mbc like the TurboXS Standard version.

3. 1 and 2 explains why your bov leaks with the mbc connected, pressure was bled off the bov line by the mbc causing the bov to open due to unequal pressure. More importantly, you have accidentally demonstrated one of many reasons why the bov line should not be tapped for your mbc. I strongly suggest that you leave this line short and un-interupted to the intake manifold and tap your compressor, J-pipe or licp for pressure source for your mbc.

I hope I made it clear.

Geez, and we wonder why you are called a DSM God.

Settle down grandpa.

Updated my profile and added a picture to my gallery to boot. I had heard about disconnecting MBC, that's why I clamped the hose instead.

My question was more revolving around how would I know if my 1G BOV leaks, as it doesn't seem to during the leak test at 30PSI.


Thanks again for everyones help.

what are the other side effects or using the bov for your mbc pressure

Fmstrat said:

My question was more revolving around how would I know if my 1G BOV leaks, as it doesn't seem to during the leak test at 30PSI.

Click to expand...

I couldn't hear my bov leak at all when I pressure tested to 25psi, spray some soapy water into the dump tube, bubble starts to appear at about 16-18psi. I also question your so call 30psi test, I have done alot of pressure tests and was never able to achieve 30psi. Are you reading the boost gauge or the gauge on the compressor?

power=dsm said:

what are the other side effects or using the bov for your mbc pressure

Click to expand...

I just posted this the other day. Pre-TB plate vs. post-TB plate.

oldman said:

1. The main reason why a lot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.

2. The proper functioning (opening and closing) of the bov depends greatly on the pressure accuracy of the BOV line both on and off boost so it's best to leave it connected directly to the manifold without any interference.

3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.

4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.

5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.

Click to expand...

Alrighty, did the pressure test again. And yes, 30 using boost gauge. First, I did a piping only test. Found one leak between two connected pipes, as soon as I tighted it, BAM popped the clamp (30 PSI all at once is friggin loud, btw). Time to order some band clamps for all of them to be safe. Anyway, replaced that and piping was OK. My BOV seems to be behaving differently now though. It now seems to leak at just 7PSI out the dump tube. And the soapy water revealed that there is a leak in the body of the BOV. Very small bubbles appeard above 25psi right in the center of the body. Guess it's a manufacturing defect. Think I'll get an aftermarket rather than modify it just to be safe.

Then did the test directly on the intake manifold. I found one minor leak, tiny bubbles at the idle screw. However, it's so small I can plug it easliy with my finger. Guess it needs a new washer. Unfortunatly, there is another leak I can't find still. It's not as bad as I first thought, as when filling with the compressor the boost gauge gets up to 25 real quick, I then stopped filling at 25psi, and it drops down about 1PSI per 2 seconds. I also noticed that the pitch of the leak sounds different if the throttle plate is open or closed. I sprayed soapy water all over the place, no luck. Sounds like it's coming from the back somewhere.

I went to put everything back together, and low and behold, oil in the inlet of the turbo. Just a thin coating, but since I'm using a catch can and the intake pipe is dry except for about an inch from the turbo having oil, I can only imagine it's oil seals. Fairly new turbo, too.

Fmstrat said:

BAM popped the clamp (30 PSI all at once is friggin loud, btw). Time to order some band clamps for all of them to be safe.

Click to expand...

Make sure you pick up T bolt clamps.

Then did the test directly on the intake manifold. I found one minor leak, tiny bubbles at the idle screw. However, it's so small I can plug it easliy with my finger. Guess it needs a new washer.

Click to expand...

BISS o-ring.

I also noticed that the pitch of the leak sounds different if the throttle plate is open or closed.

Click to expand...

Throttle body shaft seals.

Yea, I have two T-bolts already, need a few more then I'm replacing all of them. Thanks for the info, last time I looked for BISS stuff the only place I could find the O-ring exactly was ordering from MachV, but that link has the exact size in it. Will be picking one of those up soon. (Btw, O-ring is what I meant by washer).

Thanks a TON for that link about TB shaft seals. Exactly what I was looking for.