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Discussion Starter · #1 ·
Ok, here it goes...

First, my CAT broke off of the flange that connects to the back of the turbo. At this time I still had boost. The CAT broke while I was driving and it took me 10 min. to get it home. So i had boost for about 10 min after the CAT broke. The next day I took it around the block and noticed that the boost was acting weird. It wouldn't kick in until about 4 grand in 1st. Then it just wouldn't kick in at all. I cheched out the engine and saw that the "Y" looking vac line just above the airbox and check valve that is on one of the ends of it were broken. The check valve looks like it had dissipated(possibly from the extreme heat from the exhaust gases) and the vac line was cracked. I got my CAT welded back together and replaced the chceck valve and vac line. I stiil have no boost at all and am stumped. Deos anyone have any ideas as to what may be wrong? I had to do a quick write up cause i'm at work. All help is greatly appreciated.
 

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Limp mode: I think several restarts will clear the code... you also could try resetting the ecu (key-and-door trick) or unplugging and re-plugging the negative terminal on the battery.

The stuff on top of the airbox is part of either the crankcase breather or the fuel tank vapor reclamation system. It's good to repair that stuff, but that's not likely your main source of leaking boost. In addition to pancreas' O2 sensor idea (which I agree with), keep looking for frayed or worn vac lines. There's a post in the info section with descriptions how to find them. Basically replace all the skinny, braided lines coming off of the intake manifold. www.hosetechniques.com sells good-quality 3.5mm vac hose. You'll need about 10 feet of it.
 

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Discussion Starter · #7 ·
I replaced those hoses awhile back when I did my boost gauge and they are still in good condition. If I am in limp mode should the ECU have thrown an CEL, because the CEL isn't on? Thanks for all your help.
 

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Do you hear the turbo spooling up, or is it non-functional?

When you say no boost - are you using a vacuum gage to measure this, or is it a seat-of-the-pants thing? If you have a boost gage, do you get *some* pressure, or do you draw 5-10 psi vacuum all the time? Post your highest (least negative?) pressure reading.

I'm thinkin' you need to get to a vag-com.
 

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Discussion Starter · #13 ·
I do have a boost gauge and the highest reading I get is just below 0. It never goes into the PSI side. It idles at around 20 and when I accelerate it goes up to just below 0. I made an app. at the dealer for Friday, unless I can figure out wtf is wrong before then. I don't have the money for a vag. Especially if I'm gonna have to cough up some major cash to get it fixed.
 

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Unless you have a hook up at the dealer why are you going there?

With Ron at VW specialties why go anywhere else?

Unless you have an extended warranty?

I'll pray for you kid :nervous:
 

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MaVeRiC said:
I do have a boost gauge and the highest reading I get is just below 0. It never goes into the PSI side. It idles at around 20 and when I accelerate it goes up to just below 0. I made an app. at the dealer for Friday, unless I can figure out wtf is wrong before then. I don't have the money for a vag. Especially if I'm gonna have to cough up some major cash to get it fixed.
Vacuum idle around "20"? Your gage must read vacuum in units of inHg (inches of mercury). 29.53 inHg = 14.50 psi = 1.0 bar. Atmospheric pressure at sea level is around 15 psi absolute, so it's not possible to create 20 psi gage vacuum.

The turbo is doing *something*, or else you'd be at -20 inHg almost all of the time. -20 inHg = -0.68 bar: "normal" vacuum at idle in a 1.8T. I'd guess it's not a vacuum leak, since that would typically show as an idle pressure closer to zero (say -15 to -5 inHg, or so). It's also probably not a boost leak, since that would typically show some kind of spike prior to dropping off. It's also probably not limp mode - that tends to show approx 2 or 3 psi boost, not zero. What's left?...

1. Blown Turbo - perhaps. I don't know enough about "blown" turbos to help diagnose this. Perhaps you could use a long screwdriver to listen to your turbo and also to a friend's turbo, and see if there is a difference?

2. Malfunctioning wastegate/N75 valve. (I need to check Bentley to see how to diagnose this properly). You can jiggle the wastegate actuator rod on the turbo: if there is any play the actuator is faulty.

3. DV stuck open? I like the idea of this -- it seems to fit what I think would happen if the charge air were allowed to recirculate all the time. Are you still on the stock DV? Also, how's your gas mileage?

4. Cooked hoses (from exhaust leak) - have you checked the smaller hoses in the turbo area? DV hose, N75 actuator hoses, etc. These are not "vac lines" in the traditional sense, so you may not have inspected them yet.

It may be time to find someone with a vag-com in your area. http://www.steve-hall.com/cgi-bin/VAG-Locator.pl
 

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Just an fyi, my boost gauge shows a hair under "0" with engine off, about -20InHg at idle and anything in between -30InHg (coasting at speed) to 18psi (WOT around 4000rpm, APR chip, trails off in the higher RPM range of course).

I would think if he had a serious vacuum leak, he'd have other symptoms (hunting idle, etc) as the various systems fought each other from conflicting signals. Also, I'd think he'd see the needle in the boost/vac gauge move a bit as the systems tried to compensate.

I agree that I doubt it's limp mode as you should still get a 2-3 psi.

Are you getting a rattle when you are tooling around? If so, that points to a possible fault with the wastegate/wastegate rod/N75 solenoid.

One last thing (apologies if this sounds a little dumb), are you taking your measurements while moving, or just sitting in your garage? I can't get my gauge to register anything higher than "0" just revving in park. The ECU won't request any boost since you are not in gear. This also won't give you a CEL.

There's a VAG-COM locater page. Maybe you could look somebody up and they could help you out for the cost of a case of beer.
http://www.steve-hall.com/cgi-bin/VAG-Locator.pl
 

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Discussion Starter · #19 ·
I meant -20. Yes, the measuremeants are while moving. I think I can hear the turbo spool up a little or start to, but I also hear a chattering kind of noise that seems to be coming from it w/ the screw driver test. Gonna do a full re-check tomorrow. Will post any new info. Thanks for your guys' help. I appreciate it.
 
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