Hi, I posted this earlier today- but must have put it in the wrong part of the forum and my thread was deleted rather than moved. So here we go again (crosses fingers)....

I've got a 2007 2.0T A4 with 34k on the odometer. Lately I've noticed a couple of things that the dealer cant seem to figure out. I have two months of warranty left, so I'd like to fix this before it runs out.

My first issue is that the car clearly has boost issues- stepping on the gas used to throw my head against the seat. It's still quick, but not as fast as it used to be.

My second issue is that for the first 4 minutes of run time (after sitting over night) the engine runs a bit rough, and REALLY lacks pickup. Clouds of soot come out of the tail pipe if you step on it before it's really warmed up. I can see (and feel) a RPM variance of about 250 RPM during this time.

Once it is warmed up, it smooths out- but the boost issue remains.

I'm basically looking for something to throw at my dealer to try. They want to fix it as well- but with no CEL's or codes they don't know what to look for. I know that the coil packs tend to be an issue on these cars, but mine was replaced under recall less than 6 months ago....I also know that the PCV valves can go bad frequently- but that should be throwing a CEL. Ideas?

 

Hmm well the fact that there is no CEL points me to a non electrical problem but I am no mechanic so please don't take what I say to heart but I have owned an audi for the last couple of years. The idling issue sounds like a pcv valve issue, with the car idling, try taking off the oil filler cap, normally there should be a small amount of vacuum holding the cap on, but if there is a large amount of vacuum holding the cap on, making it hard to remove the cap once unscrewed, that is another indication that your PCV valve is bad.

Now if youve been around the forums at all, you may have heard of the cam follower problem. Your cam follower sits between your cam lobe and your high pressure fuel pump and over the years that the spring on the cam hits your follower, it can cause damage to it. If the spring gradually wears through the follower, you can cause damage to the cam and the HPFP. On here it is known that you should change your cam follower about every 30k miles just as regular maintenance, this is not part of the dealers maintenance but we try to stay ahead of the problems and fix them before it happens. The follower itself is a 30-40$ part you can find easily on ecstuning.com and the install is pretty easy as well. It took me about an hr and I had no idea what I was doing when I tackled the job. I'm not saying that this is causing your lack of boost but this problem does effect your fueling and fueling does effect performance so changing this would not be a bad idea either way you look at it.

The soot issue does not seem normal to me, if you have a clogged exhaust, it will cause a lack of power. If you Cat was clogged, your rear o2 sensor would probly pick it up and cause a CEL but if your resonator or mufflers were clogged, I don't see a CEL being kicked out so maybe there is something wrong with your exhaust. I'm not sure if there is a pressure check that can be done to check your exhaust but that is something you may want to look into. Maybe as it is idling, stick your hand at the end of each exhaust tip to make sure exhaust is coming out of both tips, if its only coming out of one you may have a clogged exhaust.

Other than that, you diverter valve is a known failure on these cars. You didn't mention that you have any aftermarket mods on your car but if you are modded, that usually causes your DV to fail even faster. But if your DV fails, it usually causes a boost leak and usually does cause a CEL but not all the time. So maybe thats something you can look into. The newest revision sells on ecstuning.com for about 80$ and is another part that is pretty easy to change and can be a fun DIY if your looking to learn more about your car.

Thats all I got for ya man, hopefully you get things worked out, Id have the dealership take a look at your cloud of soot problem, have them take the car overnight and have them start it up in the morning to see if they can duplicate the soot problem.

Hopefully you get it worked out, good luck man.

 

Thanks for the pointers. I have no problem tackling minor repairs- in my past life I was an ASE Certified Mechanic. I love working on my cars, but found that it wasn't my calling as a career. I know a fair bit about N/A engines, but the turbo system is a big question mark.

I know I'm getting exhaust flow through both pipes. On colder mornings I'm getting a healthy fog.

Nope, as of right now I have no mods on my car. I'm looking at doing the ASR programming once I get time...the nearest dealer that can program my ECU is about a 2 hour drive away.

I think I can talk my dealer into replacing the cam follower, pcv, and dv. Those dont seem like very high-cost or labor intensive fixes. Although I might buy the BSH PCV and do that myself...if the car is going to eat them regularly, it makes sense to put the upgraded part on it and fix it once and for all.

 

Don't count on them replacing the cam follower. It's not something Audi considers a maintenance item, so they won't change it until it fails. Once it fails and wears the cam lobe, you're well into $1000 for replacing the cam.

The boost issue sounds like a DV problem. I need to remember to order one of those when I order my window lock switch in a couple of weeks.