I don't know how people who work at dealership service departments sleep at night. I have an 01' Audi A4 daily driver. Well recently it was driving on 3 cylinders, so I bought 4 new coils--$120 later, back on 4 cylinders but the car has an obvious boost leak (tons of compressor noise, I can hear the air escaping, car looses all power). This happens as soon as the car hits peak boost by about 3.5k, it feels like the power surges, then the leak is audible, power tappers off, then theRPMs drop---this repeats until you get off the gas. I break down and have the dealership look at it, figuring they are the experts. They come back with a laundry list of problems including cracked coil conectors, a leaky valve cover gasket, leaky cam angle sensor, missing splash shield under the car... all to the tune of about $4700 to fix. I told them NO THANKS and to just fix the vacuum lines, the culprit they pointed out. Now I'm a pretty clever guy and can do most of my own work but the lazy side in me made me take it to the dealer. Labor, Diagnostics, Parts, and Shop fees came to the tune of $453.67 to replace 7ft of vacuum lines. That on its own made me stagger a little bit, but if it fixed the problems it would be worth it right? Well no, I pay, go to drive the car---same damn problem! I raise hell and they tell me they can't gaurantty a fix to the problem unless they fix everything. How the hell is a broken tab on a coil plug or a leaky cam angle sensor causing a boost leak! They tell me the car has the wrong sparkplugs in it (these are the ones Advanced Auto Parts sold me for the car less than a week ago) and that this could be a likely reason the car isn't holding boost or revving to redline under boost. Figuring it would be cheap, I frustratingly agreed to have them replaced--even a dealership couldnt charge more than $50 for plugs right..... wrong. Spark plugs and labor = $130.77. I feel like I'm going to puke. I know the dealership knows exactly what is wrong with the car and I feel like they are taking advantage of me by selling me this laundry list of parts. Granted, these parts may be broken or on their way out, but they are not responsible for the boost leak problem I took the car in for and I can not get that through their damn heads! To make matters worse there is some brainless woman service cashier that refuses to let me talk to a technician and it's blatantly obvious she doesn't have an f'ing clue what she's talking about. And the cherry on top, they left a razor blade under the intake manifold. Can any of you accurately pin down the reason the car is doing this, or have any of you experienced it. It's an odd problem, its almost like you can hear the boost POP at the right rpm and the car looses all its pressure/power. I'd say it sounds like a wastegate dump, but quieter and without any surge in power.

CLIFFS: Took Audi daily driver to dealer for simple vacuum line service, was raped anally, paid $703.77 for work and parts and car is still broken.

 

I cant understand why they have done a fault code check and given you the results? im going for the DV or one way valve/check valve on the turbo system ( its plastic and degrades quite quickly ) I dont have a picture of it but some have had the same problem so perhaps they might have the data you need

 

Im going to talk to the Tech who worked on my car this afternoon and see what he thinks. I checked the Diverter valved, pushed on the plunger and when I released there was suction on the nipple--isn't that the way you test it? It sounds so obvious, like there is a coupling loose or something but I didnt find crap.

 

there is a vacuum line with a check valve in it which has caused problems for others by rotting away hence the lose of boost ( turbos not my area so just a guess ) but I did note others showed pictures of the said valve

 

Well this should be a lesson learned, get a estimate before ANY work is done. Dealer plugs are like $15 a piece, plus you are paying almost an hour of labor. Be happy you don't have a 2.7t.

Really the only way to test for a boost leak is to pressure test the system. If you have the time, you can inspect all the compressor side, take every part off, & reinstall while checking for cracks, or beaks in the parts.

Are you sure it's leaking boost? My bet is also on the DV, or maybe a N75 going out?

Really it's almost impossible for us to help with out seeing some logged runs, or codes.

 

Do you have a boost gauge in the car? Or the loss of boost is just the sensation you feel best decribes your problem?

 

No boost gauge in the car, I guess the problem could be best described as a loss of boost feeling, coupled with a loud rush of air from under the car. Oddly enough though, when driving the car last night, it kinda fixed itself. The loud leaking boost noise went away and the car has consistant acceleration. The kind of scary thing though is that it feels really slow and it doesnt have the peaky-ness I remember. (Ive been driving my GTO for awhile, and the A4 has been broken for a while). The other scary part is that I was seeing puffs of smoke from the exhaust and that has me thinking that my turbo might be ready to take a dump. I can still hear the car spooling and blowing off though, but it might be slowly dying? I guess it would make sense if it was spinning to oblivion trying to keep up with a boost leak. I havent been able to make it smoke again, and it was dark so I dont know the color and I havent smelled it. This weekend I'll take the snorkel back off and feel for shaft play. I'm praying that the turbo can hold up long enough for me to sell the car, or that it really wasnt smoking, rather it was the carb cleaner being burned off that I was using to find vac leaks.

 

carb cleaner ? that explains a lot it does smoke with that

 

UPDATE: Car hasnt smoked since last night. I really think it was just burning off the carb cleaner that was sprayed in the bay. My theory is that the car is in "safe" mode and only allowing itself to generate 3 or 4lbs of boost (thats my psi guess, it's building boost, it's just really weak). The turbo looks healthy. As far as I'm concerned, it can stay in safe mode--I dont need alot of boost for it to get good gas mileage.