Can't find the boost leak. Am I insane?

[Tumbler510]

Boosted to around 20ish PSI, and car shut down. Dead.
Got it home, charged the battery (a separate issue apparently), and the car runs very rough and has terrible throttle response.
I unplugged the MAF, and the car runs fine, normal throttle response.
Plugged in my leak tester, and i can't find any escaping air.
Any ideas on where to check?
Could the MAF have crapped out all at once?

[TheDarkness]

check throttle body boot first, then make sure you smoke test/pressure test with enough PSI if you're still not finding a leak.

Replace that MAF, they need replacing every once in a while anyways

[Tumbler510]

check throttle body boot first, then make sure you smoke test/pressure test with enough PSI if you're still not finding a leak.

Replace that MAF, they need replacing every once in a while anyways

TBB doesn't give off any hissing noise, and doesn't put out any air that I can feel with my hand when testing.
I started with 5PSI, worked my way up to 15.
It seems odd that it would just go out completely in one second.

[2000s4_m]

Really dont think its a boost leak, it has happened to me and you can still drive it, it wont die on you that sudden, i thinks you're more into ICM or fuel related (fuel pump)


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[88ninety9]

Really dont think its a boost leak, it has happened to me and you can still drive it, it wont die on you that sudden, i thinks you're more into ICM or fuel related (fuel pump)


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When my icm went out it gave me the same symptoms as when I tore my tbb. I also pressure tested when my tbb ripped, and never found it until I actually removed the tbb. No faults in the system?

[Tumbler510]

When my icm went out it gave me the same symptoms as when I tore my tbb. I also pressure tested when my tbb ripped, and never found it until I actually removed the tbb. No faults in the system?

No Vag-Com codes.
Car will run forever with the MAF unplugged, so I don't think it's fueling.
If it were ICM, I would expect the same issues to occur with the MAF unplugged as plugged in, right?

[Dalers08]

Do you get super loud turbo whistle sounds when you're driving with the MAF unplugged? Check under the car the intercooler hoses that come right off the turbo.

[CELison]

If it runs fine with the maf unplugged you have un-metered air post maf, pre manifold. You have a big leak. Find it

[CELison]

Really dont think its a boost leak, it has happened to me and you can still drive it, it wont die on you that sudden, i thinks you're more into ICM or fuel related (fuel pump)


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It runs fine with the maf unplugged. It's a leak.

[Zba]

Agreed. Squeeze and wiggle your hoses while leak testing and use soapy water for fucks sake

[2000s4_m]

No Vag-Com codes.
Car will run forever with the MAF unplugged, so I don't think it's fueling.
If it were ICM, I would expect the same issues to occur with the MAF unplugged as plugged in, right?

Do you have an extra maf? To try and see if its the actual sensor that went wrong


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[Tumbler510]

If it runs fine with the maf unplugged you have un-metered air post maf, pre manifold. You have a big leak. Find it

I jsut unloaded a few tanks of my compressor trying to find it. Not a hiss or any air movement I could detect. Any way it could be in the spider hose or one of the mechanical parts in that line?

[LINDW4LL]

I jsut unloaded a few tanks of my compressor trying to find it. Not a hiss or any air movement I could detect. Any way it could be in the spider hose or one of the mechanical parts in that line?

Does your gauge show the system holding pressure once the air source is turned off?

Also, does it feel like you're getting boost with the MAF unplugged, or is the car super slow?

[Tumbler510]

Does your gauge show the system holding pressure once the air source is turned off?

Also, does it feel like you're getting boost with the MAF unplugged, or is the car super slow?

I don't pressurize the system, so there's no telling.
I haven't driven it with the MAF unplugged yet. It has been on jacks since it was towed back.

[LINDW4LL]

I don't pressurize the system, so there's no telling.

How do you test then?

[Tumbler510]

How do you test then?

Flow air into where the air filter usually is with the oil fill cap removed and the pancake valve port blocked.

[LINDW4LL]

Flow air into where the air filter usually is with the oil fill cap removed and the pancake valve port blocked.

OK, that's what I meant. It should look like this as far as holding pressure...

[Tumbler510]

OK, that's what I meant. It should look like this as far as holding pressure...

Oh yeah, no gauge on my leak tester

[AudiTechS4]

reading these comments amuses me CELusion they have no idea what they are doing

[AudiTechS4]

please if you have no idea how engine management system works don't reply with your fixes . your just leading them in the wrong direction

a maf calculates airflow thats it .

[Tumbler510]

please if you have no idea how engine management system works don't reply with your fixes . your just leading them in the wrong direction

a maf calculates airflow thats it .

Yup.
Any ideas I can try?

[AudiTechS4]

I've had a broken intercooler where the whole top.broke off and you couldn't even hear the leak because it was so big. You need to see if it's holding pressure

[AudiTechS4]

As said before pressure test with some kind of gauge and check valve to see how it holds pressure

[DxC]

Maybe you bent some valves. Maybe r fuel pump died

[Tumbler510]

Maybe you bent some valves. Maybe r fuel pump died

Don't think so.
I have compression because the car is running.
And my fuel pump is working because the car is running.

[Tumbler510]

If it helps any, the car runs fine when I have the clutch in.
The second I let eh clutch out (even in neutral),the car gets the rough idle, and stalls.