Hey guys so Ive been extensively searching for a boost leak due to a idle surge issue. I have it holding just about as good as I have ever seen my car hold pressure, so I am wondering how the speed at which pressure bleeds down compares to yours?

Any input is welcome. My experience with boost leak tests extends to only my car, if yours holds better or worse, let me know.

Thank you

Nobody has any comment?

Its not a trick question....

Seems to hold low boost decent, but that pressure is really low for a good test, especially with your turbo. Leaks are much easier to find under higher pressure.

Fair enough. I will up the regulator from 30 psi. I am filling through a 3/16" hose so it takes a while to build up to 20+ (where the tester gauge maxes out). I will move my good boost gauge to a location I can see it while I am filling, and try to get it up to 30psi.

Car has idle surge and I am pretty sure that 20+ psi is more than adequate for determining if I am leaking air at idle, but who knows.

Thank you for your input Ill try to post another video at 30ish psi.

I can reply tomorrow as I am doing my friends talon, he has leaks barely , dont forget to use soapy water aswell, the big tends to open it's self so hold it down or closed lf possible,

I've found that the smaller the leak the more pressure I had to use to find it. Had a similar issue I was trying to track down, held 20psi similar to yours and I couldn't see any leaks. But as soon as it hit 25psi the leak started to whistle. Tightened it down and fixed the problem.

I am shooting for 30 psi in the next test. I hope I find something!

Just did a boost leak test today and after fixing the leak the pressure went down much slower than yours. I'd say you definitely have a boost leak. If you have a manual boost controller be sure to remove it for the test. Make sure you spray with soapy water all vacuum lines and afpr, injector seals, bov, brake,booster, and also make sure it's not leaking from your tester too

Excellent, this is what I was looking for. I have covered the obvious places and still never found any air coming out. I do have my valve cover breather going to a vented catch can fwiw.

I thouroughly checked the vac diaphram on the cyclone actuator setup, as well as the fuel pressure regulator and tial wg separately. I used a hand vac pump to pull 22 in hg on each one and made sure they didnt bleed off over a period of about 15 mins. I have not yet checked the brake booster VD, so I will block off that port at the manifold next time I test, and try to remember to do that.

The tester is just a 2" block off in the IC pipes at the turbo outlet and the air sprayer connected to the vac port in the manifold.

On a side note, I swapped my throttle body out to my previous one which has the FIAV and ISC deleted from the bottom. The car has zero idle surge and I can choke the engine out with the BISS screw. So my idle surge was from one of the valves on the TB and not a vac leak. But I still want to expand my ability to find leaks, so keep any opinions and insight coming. Thank you

The speed in which it bleeds down can vary with crank position. There's points in the rotation where valves will be open at the same time.

Yes, but I routinely set to TDC for BLT to keep the tests consistent. I should maybe mention that too.

I had in my head that this minimizes the leakage past the valves because they are barely open at that angle, but maybe there is a better position to test at? That could potentially be why Jacolu3 has a slower bleed down? Or I could have hidden leaks, still acknowledging that's a possiblity

Yeah I just meant comparing his to yours might not necessarily be right since the valves could be at different positions.
I've never really paid attention to the speed in which it leaks down, just test around 10psi higher than my boost level and check for leaks big enough to feel/see. Alot harder to find an internal leak though .

Yea thats a pretty good point, it would vary for anyone, at the time I was really trying to rule out a big enough leak to be causing my idle surge. Now that I know idle surge is gone I have found out that my pressure tests aren't being done very well.

If I run 24 psi I should try to achieve 34 psi in the system? I always thought you were supposed to just set your compressor regulator to 10 psi over the boost level. I don't have a boost gauge that goes that high. My auto meter only goes to 30. Should I disconnect it before putting that kind of pressure in the system? or just avoid burying the needle against the stop? It looks like it has some overshoot wiggle room.

Yeah I wedge the throttle open pressurize the system at the turbo til a gauge on the manifold reads around 50psi.
I'm sure testing it to 30 would suffice in your case.
As for the gauge I can't imagine pegging it out is good for it, but I've done this plenty of times in the past and haven't broken one. Don't know much about how they work internally but it seems it could push the needle out of calibration.

Yea Ill just keep the air blower valve open until its nearly pegged. thats 30+ psi and should be good enough. Thanks for your time.

Some interesting reading on mechanical boost gauges. It shows how you could calibrate one if it did get damaged during a high pressure test. I guess the adjustment is a bent rod so over pressure probably could cause a calibration issue, but that assumes the needle is rigid enough to not bend first.

http://www.ozfalcon.com.au/index.php?/topic/2066-gauges-how-to-gauges-how-to/