Questions about Audi S6 C4

[I Boost]

I am new to cars, as this is my first vehicle. My 1995 S6 has a stage 1 chipset and with this, I should be pushing around 16-20psi of boost after some research. My boost gauge consistently says that I push max boost at 5psi and I am wondering why that may be. I couldn't find any forums or threads that have someone with similar problems so I thought I'd post on here. Any suggestions or input is appreciated!

[4rings2turbos]

First off:

WHAT A SWEET CAR FOR YOUR FIRST CAR!! Post up some pics! Sedan or Avant?

Alrighty, down to business. That car is a bit of a handful for a first car. A number of things can cause your car to under boost. First and easiest: do you hear any loud 'whooshing' sounds when you're under heavy throttle? That would indicate a boost leak. Secondly, is there a MIL (malfunction indicator lamp, in laymans terms check engine light)? If there is, it I possible that the engine is seeing something wrong and limiting boost because of it, known as 'limp'.
If there is a light your local auto parts store will scan it for free and give the the generic code that the ECU has stored. If you'll be in the Audi/VW scene for a while then you might consider looking into VCDS. With this cable/software combo you can dig real deep and get a ton of info from your car. $350 for a licensed cable and the software is free. There is a way to pay for the software and buy a cheap cable of eBay for $99 but I have no experience with this.

I hope this kind of gets you on your way. Please post up any more questions or details and we'll help you as much as possible! I have experience with two C4s of my own but only the 2.8L A6 so my knowledge of the AAN engine is limited. But I do have a couple friends with them so I can ask some questions on your behalf. This forum is kinda quiet when it comes to the C4 so you might consider posting in the 'misc and classic audi models' section as the AAN has been used I several other older audis.

And definitely post up some pictures and maybe an into thread. Welcome to Audi!

[I Boost]

I really appreciate the reply! I will attach some pictures to at the end of this message! I thought it could be in limp mode, but I don't think that is the case because every once in a while it WILL push full boost at around the said 16-20psi. But now that you've brought it up, there is a check engine light that is on consistently. I'm also not sure of the boost leak issue because when it is under a heavy load, it consistently stays at exactly 5psi and won't even budge past it. I haven't noticed any strange sounds coming from the motor, but then again, I am 16 and I am not terribly sure what kind of sound could be considered strange. The reason I thought I needed to buy an Audi is because my dad owns a 2012 S5 that is heavily modified, and I also have a friend and a older mechanic friend who knows just how special this car really is. He actually made the arrangements for me to buy it! It is the sedan and here are the following modifications: stage 1 chip, custom front mount intercooler, full 3" magnaflow exhaust, 1.8t coil conversion, and a boost gauge of course. Here are the imagesIMG_1964.jpgIMG_20150810_122953670_HDR.jpgIMG_20150810_123041422 2.jpgIMG_1474.JPG

[4rings2turbos]

Of course my man happy to help.

Steady 5psi does sound like limp mode, or maybe torn diverter valve. Getting a scan would be a great first step. After that, if your dad doesn't already have VCDS now is the time to convince him that he needs to buy one for you both to use :)

With that you can log the data as you drive and it will show you requested boost vs actual and you'll for sure whether you're getting the PSI requested or not.

Love the car, black is sweet. Also has clear turn signal lenses and an aftermarket bumper from what I can see. I dig those vents on the side.

[I Boost]

Yes, I will take it in to O'reilly or Autozone to get it checked out. I am currently trying to convince my dad to buy it! I was having trouble finding the exact VCDS I would need. We'll see. I also have a quick question; if my diverter valve is torn, I found a billet one off of 034motorsport for about 100, but I am curious to see if I can throw a BOV on there without having to retune it because it seems like common sense that the motor/ecu still thinks air is being recirculated instead of being blown off. Would it result in the motor running badly? Thanks again

[4rings2turbos]

It's such a great tool and will pay for itself in the first two diagnosis. I got mine from Europaparts.com great company, they're a forum vendor and only stock high quality parts and are extremely competitively priced. You'll want the $350 one, if you guys have any question just open up the live chat or shoot Hugh an email.

A BOV will mess things up and for longevity and simplicity it's best to stick with a diverter valve. That billet one will serve you very well.

[I Boost]

So here's an update, my car is pre-1996 so it still has OBD1 and it doesn't have the port to check the ecu when I went to autozone. After school today I will be performing the "jump" method to check the sollenoids, because I think that it may have something to do with the wastegate sollenoid.

[4rings2turbos]

Ahh, see this is where my limited C4 knowledge comes in. I should have known.

Okay, there is a way to retrieve codes without any equipment. Let me look it up for you, hold on.

[4rings2turbos]

Reading fault codes via blink sequence.

So here is a very convoluted way of retrieving codes, but it is free. That article will get you started, the idea is bridging two sensors while the engine is running and the MIL will blink a sequence. The MIL will blink a number of times then pause for 2.5 seconds if it blinks twice before the pause that's a 2, it blinks 4 times before the pause that's a 4. And so on. The codes are four digits long.

Let me know if that makes sense. Try this out and post up your results and I can help you search for the meaning of them.

Good luck!

[I Boost]

Thank you! I will keep you updated

[I Boost]

So here's the story. I pulled the fault code 2113, and it just kept repeating this fault code so I think it is the only one. I found it on the website you provided above but as I've stated before, I'm new to cars so I don't know what it means. "2113 (Blink Fault Code), 00515 VAG1551/2 Fault Code Number
(G40) Hall sensor in distributor
(3B, early AAN engines) or camshaft position Hall Effect sensor later S4/S6 AAN engine).
Distributor alignment, faulty sender, Mis-located sensor & distributor, Cam timing possibly incorrect on AAN engine, Check lower Crankshaft Gear keyway"

[I Boost]

Alright, so I just performed the system output test, and the only solenoid that did not click was the n75 wastegate solenoid. What does this mean for me?

[4rings2turbos]

Sounds like you need to replace the cam position sensor and the N75 valve.

here's the G40 CPS (camshaft position sensor) location it looks like the cam sprocket comes off. (ignore the early AAN info, yours is late model)

A bad N75 will definitely cause boost issues, not uncommon for them to die. and your N75 info

[I Boost]

Great, I just ordered the N75 valve. Is it a necessity that I get that cam position sensor immediately?

[4rings2turbos]

It's possible that the engine can cut out if it's not getting signal. That thread about the cps goes into what the engine uses it for and the two other sensors the ECU uses to start the engine and keep it running.

But if you don't mind running the risk of needing a tow then it won't do damage. Usually your insurance company will tow you for free if it does happen to die.

[Bordom]

Not a fan of that bumper. Really contemplated picking up a C4 S6. Looks real clean other wise

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