Boost Leak

[baker1o7]

Ok a little history,

The car is an 01 6 speed. Just finished installing stage 3 parts (see below). and have the a tune from Blake Beadle, base stage 3. Started the car and had a very rough idle, running rich, and would die. So assuming there is a boost leak I unplugged the MAF and the car smoothed out and ran fine, albeit rich. So attempted to pressure test the system but I can build zero pressure. Cant hear any leaks and visually inspected the connections I could see. So now I have a smoke machine to hunt out the leak. Put smoke to the system and the only place smoke was getting out was from my exhaust. I am stumped, is one of the turbos (both maybe) fucked and the pressure is by passing the seals? or is a waste gate or check valve on the spider hoses stuck open. Any help is appreciated.



RS4 K04's
85mm MAF
550cc Bosch EV 14 Injectors
Bosch 044 Fuel Pump
Wagner Sidemount Intercoolers
APR Diverter Valves
Cold Air Intake
3" Downpipes
3.5" Single Exhaust
034 Bipipes

[Cysco abt S4]

Do a compression test check your timing test vacuum lines to wastegates

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[baker1o7]

Dont have the means to currently do a compression test, timing is good as the car runs fine, and I will attempt to test the vacuum lines to the wastegates.

However, how would these items effect a boost leak test from the y-pipe to the throttle body

[616_S4]

What do you mean build pressure? You don't build pressure in a boost leak test. You're simply putting through a certain amount of pressure through the system.


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[chaos2984]

What do you mean build pressure? You don't build pressure in a boost leak test. You're simply putting through a certain amount of pressure through the system.


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This. You need an air compressor and a regulator. I just did mine and Hooked it up and pressurized to 20psi with continuous flow. Found a small leak with mine. You will hear it even if small.

[Zba]

What do you mean you don't build pressure? What do you think a leak test does? You put 15psi through the intake it should slowly drop. If it won't build pressure, there's a massive leak.

[baker1o7]

Ok, instead of running constant air on the system I built a similar system as the AWE DIY tester. Instead of an air line quick coupler I used a one way valve and attached a gauge after the supply air valve so I could put the desired amount of pressure to the system and use the gauge to see the amount of pressure in the system, and if it bleeds off I know there is a leak somewhere.

I went this route because from what I understood was that the system from the intake to the throttle body is closed and should hold pressure.

But from what I am reading that information was incorrect and the system is open so no air pressure would build

[baker1o7]

Some pressure should build in the system though if there isnt a "major" leak. So thats what lead to a smoke test and the actually question of why am i looking pressure out of my exhaust

[chaos2984]

Well you are going to loose air into the cylinders because one or 2 of the cylinder will have the intake valves open. And If your looking it through the exhaust. Then either 1 of two things you have burnt exhaust valves or you have a little overlap in that cylinder and thats where its coming from. i would run a compression test.

[spacecadet]

Where are you putting the tester?

[Zba]

If it ran fine before the turbo swap I doubt he's looking at burnt valves. What MAF and what ecu/tune do you have? Forget your findings for a sec.

[chaos2984]

If it ran fine before the turbo swap I doubt he's looking at burnt valves. What MAF and what ecu/tune do you have? Forget your findings for a sec.

Sorry forgot about that. But did you put a Timing belt on when you did the stage 3 install. Also what are your fuel trims. Everything plugged back in correctly. Any cel's. Sounds like a case of something simple causing the issue. Is it missing on 1 cylinder. Also what is the vacuum reading at idle?

[AudiTuner1187]

If you unplug MAF and it runs fine there's your problem. Something with that, maybe tuned for wrong one?

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[RocksForsSale]

Dont have the means to currently do a compression test, timing is good as the car runs fine, and I will attempt to test the vacuum lines to the wastegates.

However, how would these items effect a boost leak test from the y-pipe to the throttle body

Get the cheapo c tester on amazon, works great. I did mine while swapping out plugs.


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[616_S4]

This. You need an air compressor and a regulator. I just did mine and Hooked it up and pressurized to 20psi with continuous flow. Found a small leak with mine. You will hear it even if small.

Someone knows whats up, ive found that the smallest leaks are the loudest, Ive had a huge leak from a hose half off that i could only hear turning the pressure up a little because its a deeper note sound.

What psi are you putting through?

[Trb1]

I'm sorry, but what? This thread is full of misinformation.

If your car runs smooth after you unplug the MAF, skip the compression test/leakdown/wastegate lines. Waste of time. Motor is fine.

A boost leak test will build pressure. Yeah, it will leak out slowly, but you should be able to sustain pressure for some time with no leaks.

If your MAF is unplugged and the problem gets better, it is more than likely going to be a pressure/vacuum issue. MAF gets unplugged -> ECU goes blind -> ECU goes into an open loop A/F ratio -> car runs smoothly because it isn't constantly trying to adjust the ratio due to an unmetered air leak.

If your car is dying out with the MAF plugged in, I guarantee its a massive leak at an inter cooler or at the throttle body boot.

Edit: You didn't see the smoke leak in your engine bay because a smoke test doesn't build pressure like a pressure test does. You'll have to do some more convincing to find that leak. zero pressure built = leak.