What could these codes mean??? And what could this sound be? (With video)

[2k1audiS4]

I am thinking of buying this 2001.5 S4. I ran the codes on it and this is what came up:
P0300
P0507
P1136
P1138

It sounds like there is a shhhhhhhhhhhhhhing noise in the back of the engine. Like there is air blowing out of a hose. Its constant and does not fluctuate when you press the gas. Would this just be a vac hose that is off or could it be a turbo going bad? Turbos sounded fine when i revved it and there is no white smoke or anything. It has 95k miles on it and it does have 710n's. Please any help would be appreciated. I am getting the car pretty cheap(under 10K) because i have access to wholesale dealer auctions so i can put a little into fixing what ever it is. I just dont want to have to replace the turbos if that is what this noise is. The sound is noticeable if you have the hood up but not noticable if the hood is down. Here is my cell phone Video:
http://www.youtube.com/watch?v=BVXV-tYPkJs

[S4 in_lowplaces]

P0300 cylinder misfires
P0507 idle control system running high
P1136 bank 1 is running lean
P1138 bank 2 running lean

with that many miles you'll have to replace turbos soon anyways, there really no way of knowing how much longer they will last.

edit: probably needs a tune up. that might clear the codes. as for the noise, i cant tell ya sorry.

[2k1audiS4]

But could that shhhhhhing noise be a turbo or is it likely just a boost leak?

And could those codes be fixed with a couple o2 sensors?

[Jsmooth65]

pressure test that biotch

[2k1audiS4]

I wish I could but its not possible before i buy it. Thats why im trying to get a sense of if it is a turbo or not.

[S4 in_lowplaces]

well since the turbos dont have load on them i woudl think that sound isnt the turbos. It's probably a vacum leak. you just need to realize that its very hard to tell how long that leak has been there, making the turbos work harder to produce the boost that is being requested. Also, I'm not a tech, that noise coudl be somthing else.

If it was the 02 sensors you woudl see a code for 02 sensors which you are not seeing so.......

go to audi world and type in each code in the seach engine and read through them, that WILL help you.

[2k1audiS4]

Anyone else? Sorry to sound pushy but i really need the help. I am buying this car soon. I cant find anything on what the codes or the sound might be. Thanks for everyones help.

[RuS4ty]

Brake booster hose

[AudiSportB5S4]

WG line from turbo?, lol just throwing it out there ive seen that recommended before!

[AudiSportB5S4]

Brake booster hose

thats a huge vac leak if it is, the idle would be ASS probably [O_O]

[2k1audiS4]

It idles fine thats the weird thing. You would think that it would idle like crap if it has that big of a vac leak.

[RuS4ty]

thats a huge vac leak if it is, the idle would be ASS probably [O_O]

true. Just threw it out there since it was from that area and sounded like a vac leak.

[AMC]

check the spider hose connections, they make that noise when loose and from the video it sounds like its comming from that area

[2k1audiS4]

What/where are the spider hoses?

[AMC]

What/where are the spider hoses?

see that hose that goes into the firewall right between the firewall and y pipe, follow it and check it

[2k1audiS4]

Any other ideas about what could be causing the codes?

[The_Jerbel]

Wow, I'm surprised nobody has recommended doing a boost leak test yet. Do one.

[ThirdStrike]

check the spider hose connections, they make that noise when loose and from the video it sounds like its comming from that area

id bet on teh spider hose too.. the plastic gets britle and usually cracks.
if you look on both sides of your valve covers theres a breather port on the outside that has 2 of the 'legs' of the spider hose. the meeting point for them is under your y-pipe/accordian hose. check it

[pdq 5oh]

It's probably a vacuum leak. That would explain the lean codes and idle code. The idle air control bleeds air to control idle speed. It'll just shut down to compensate for the high idle caused by a vacuum leak. On fuel injected cars the idle doesn't necessarily get terrible with a vacuum leak. Fuel is added to try and compensate for the lean condition. But only so much will be added at idle. At cruise is where the lean condition is most often picked up by the ECU.

[archimense]

well since the turbos dont have load on them i woudl think that sound isnt the turbos. It's probably a vacum leak. you just need to realize that its very hard to tell how long that leak has been there, making the turbos work harder to produce the boost that is being requested. Also, I'm not a tech, that noise coudl be somthing else.

If it was the 02 sensors you woudl see a code for 02 sensors which you are not seeing so.......

go to audi world and type in each code in the seach engine and read through them, that WILL help you.

I second this opinion.

Probably a boost/vacuum leak. It needs to be pressure tested. Boost leaks cause the turbos to work harder to maintain requested boost -> killing the turbos.