Power loss update

Yesterday I took apart my car and cleaned the intake manifold and egr. But now I have a new problem. Car goes into limp mode almost right away with a CEL. Before it goes into limp mode there is almost no power with a hissing sound. I know it has to be from what I did yesterday.

Start car, sounds kinda normal, maybe a tiny ticking sound but nothing really noticable. Oil pressure light flashes occasionally. Start driving and there is no power, with a hissing sound. I'm wondering if this is that I didn't tighten something down properly, like the manifold itself, or if I accidentally pulled a boost line somewhere along the line. The turbo still whistles normally.

Does the oil pressure light go on if there is an air leak out of the engine, reducing the pressure? Any help is appreciated, thanks

My guess is vacuum leak. Check all you lines and connections.
Good luck!

Sounds more like a boost leak. The oil light flashing is definitely not good though! But I don't think it's the cause of the hissing noise. Did you replace the intake gasket? Made sure the head mounting surface was clean? Did you replace the EGR gaskets? Any of those leaking will cause said hissing noise, and can immediately cause a power issue/CEL

Nero Morg said:

Sounds more like a boost leak. The oil light flashing is definitely not good though! But I don't think it's the cause of the hissing noise. Did you replace the intake gasket? Made sure the head mounting surface was clean? Did you replace the EGR gaskets? Any of those leaking will cause said hissing noise, and can immediately cause a power issue/CEL

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Replaced all gaskets and o-ring on the EGR. Head was clean when I put the new gasket on. I'll have someone with a VCDS do a scan for me and see what comes up.

Have the car scanned while the CEL is on.

I'm thinking boost leak also for the hiss.
I found my leak by spraying soapy water on the boost tubes from the turbo to the EGR valve.

Are you sure you reconnected all the vacuum hoses correctly?
Are any of them cracked?

wonneber said:

Have the car scanned while the CEL is on.

I'm thinking boost leak also for the hiss.
I found my leak by spraying soapy water on the boost tubes from the turbo to the EGR valve.

Are you sure you reconnected all the vacuum hoses correctly?
Are any of them cracked?

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I still have OE vacuum lines. Should I just order a roll and some clamps and re-do the system? Seems like that may be worth it for me, all mine are still the braided ones so I don't know how well soapy water would work.

Soapy water only works on positive pressure air leaks, not vacuum leaks. However, having exhaust and/or boost leaks can be found with soapy water. EGR piping would be classified as an exhaust leak.

Nero Morg said:

Soapy water only works on positive pressure air leaks, not vacuum leaks. However, having exhaust and/or boost leaks can be found with soapy water. EGR piping would be classified as an exhaust leak.

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So my leak would be in the vacuum leak category then?

I don't think so. I'm still leaning towards either exhaust or boost leak. Vacuum leaks are pretty quiet and hard to hear with the engine running. Boost/exhaust leaks will make the hissing noise you're hearing.

Nero Morg said:

I don't think so. I'm still leaning towards either exhaust or boost leak. Vacuum leaks are pretty quiet and hard to hear with the engine running. Boost/exhaust leaks will make the hissing noise you're hearing.

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I just scanned it and it came up with a p1556 code. Something to do with negative charged air or something like that. did replace a couple aging vacuum lines as well, to no avail. what should my next step be?

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That code is lower boost than expected. Could be a vacuum issue like leaks or low absolute vacuum, or a bad boost leak. What's your vacuum at? Measure at the small nipple off the hard plastic line off the vac pump. Just tee in a fitting with gauge. Should be at least 20inHg.

Do you still have the hissing sound when driving?

Nero Morg said:

That code is lower boost than expected. Could be a vacuum issue like leaks or low absolute vacuum, or a bad boost leak. What's your vacuum at? Measure at the small nipple off the hard plastic line off the vac pump. Just tee in a fitting with gauge. Should be at least 20inHg.
Do you still have the hissing sound when driving?

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I don't have a mity vac. The hissing sound contines while driving, with low power until it cuts into real limp mode where it stops. I assume the computer is tleling something to shut off because of the leak.

Definitely sounds like a boost leak then. Restart the car, then simply Rev it up in park/neutral. It'll boost to about 3-5Psi, which will be enough to get bubbles to form if you soak your intake, egr, boost pipes with soap.

Nero Morg said:

Definitely sounds like a boost leak then. Restart the car, then simply Rev it up in park/neutral. It'll boost to about 3-5Psi, which will be enough to get bubbles to form if you soak your intake, egr, boost pipes with soap.

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Like soak the intake manifold?

Maybe I didn't tighten some of the bolts down good enough when I replaced the intake manifold. I'll have to take it apart again and see

Torque for intake is 18ftlbs, some of them are a butt to get to, just did one last weekend lol

Nero Morg said:

Torque for intake is 18ftlbs, some of them are a butt to get to, just did one last weekend lol

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if the intake isn't tight enough will it throw that code?

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Very well could. Boost leaks would cause specified boost request to not be meant. Thus, code for underboost.

Vacuum lines to the VNT are the most likely cause, with original lines you almost certainly have a vacuum leak. Could also be a leaking actuator but the lines are cheap and easy to replace.