AUJ

Yes, the 3.2 has kind of a carbon buildup reputation, but is not 100%. The way I have applied it successfully on Audis in the past is using one third of the can into the brake booster vacuum hose while revving the car at a constant 3500 rpm with hose barely connected. I use a 2 x 4 and towels and set up the reclining seat to keep a perfect rev on the accelerator. As soon as you get the product in, turn off ignition and let it sit for a couple hours. Then, start it up and rev it up to clear what deposits are possible. Very much white smoke, do not be afraid. I have used this on many cars, and every car I acquire used as part of preventive maintenance. I have cleared issues as described above, but if it is too far gone (like blinking MIL), odds are you need to move up on the invasive solution protocol. At about $10 a can, it could be a worthwhile venture before taking it in to dance with the dealer service reps. Just pour the other two thirds of the can in the gas tank to clean the line in side of the fuel system. If your runner system is already diagnosed as mechanical, then it will take invasive surgery to correct. Others with Vag-Com can run diagnostics of the solenoids to rule out electronic causes first. Just pop open the Engine Controller and run the diagnostics. It will cycle everything from individual injectors, secondary air, evap purge valve, and even engine mount solenoids on the 4.2. Sincerely hope your issues resolve. I did not know that Seafoam has an intake spray until this thread opened here. Will try it out on the 4.2 and report back on the functionality.

The Seafoam feedback site operator recommends the misting for a better cleaning. Seafoam is not a substitute for what is offered at the dealer, but may offer a cheap intervention to prevent that dealer visit in less extreme cases. Had a 2.7T that had a rough idle. After Seafoam, I had to check to the tach to see if the motor was even running. Butter smooth idle after. That was the most positive outcome from personal experience. Even run it for 100s of miles in the crankcase to prove some from another forum wrong on the "dangers" of Seafoam on other forums from "experts" residing there as well. Not selling it; just believe on first hadn success and safety of use as personally tested by a self proclaimed non-expert. If your intake is horrors, than it is up to an individual as to whether Seafoam will make it worse, for $10.

Here's a YouTube posted by Emling on an A5 3.2 Seafoamed intake to give you an idea of the smoke. There are also examples posted on YouTube with guys using the spray on Audis as well.

AUJ

Here is a general spray instructional posted on You Tube from the company; since you asked.

Newbie123

AUJ,

Thanks for the info including the videos.. Very insightful. As you noted I am struggling with a mechanical issue. Within the next few days when I replace the IMR position sensor/potentiometer, I will know for sure if I have to replace my intake manifold on the 06 3.2 liter. If so, I will see and be able to share with all what my intake valves/ports look like at 126K miles. From an observational standpoint, I have not had any rough idle or flashing MIL. Just very brief rough idle on cold starts in the recent cold weather. I have not always run premium gas and, have never added any upper engine cleaner other than an occasional bottle of Techron.

I may be the poster who first took this thread off topic. If so, my apologies to all that I have offended. Selfishly, I couldn't help myself. The information that was provided in this thread is of great assistance to Audi novice such as myself. While I have toiled with many a muscle cars in my day, (still own my 68 396 SS/RS camaro convertible), way over my head here.

I believe there are many factors in come into play regarding the likely hood of carbon build up and associated symptoms including engine design, driving style, maybe quality of gas, etc. However, if I know that I can have any chance of avoiding them with relatively inexpensive maintenance, I am going to spend the money and time to do it.

Thanks to all who continue to share their knowledge of these cars that I have had a love hate relationship since my first one. Love them when all is well. Currently haunted by code P2006 day and night.

Happy Holidays to All

raj99

Hey Newbie123,

Things that have a direct impact on carbon deposits are:
- Fuel quality: The crappier the fuel, the more impurities and the more likely there are to be deposits to collect - go to http://www.toptiergas.com/ for more info
- Driving distance/engine temps: Those hit hardest are short distance driving, where the engine never gets up to temp. Getting the engine hot means that the gunk won’t be able to collect as readily, because it’s baked off by the high temps.
- Poor seating of the cylinder rings: More oil seeps by into the fuel adding to the large amounts of particles recirculated into the intakes. Use of more than 1Qt of oil every 5K miles means higher than average oil consumption usually meaning poorly seated rings, causing excessive blow-by

So all C6 3.2 engines are DI (Audi calls it FSI), they are the first OEM to make ALL their engines this way. DI is really great for making the fuel/air mix ratios and concentrations perfect, it takes less fuel to make the right mix with DI, it takes less fuel to get the same power using DI, and it can also fight knock (pre-ignition, which harms engines) since every injector can operate independently – allowing the ECU to control the fuel to every cylinder individually. It is also used if the engine gets too hot and the coolant cannot keep up by purposefully putting extra fuel in which will evaporate harmlessly but take heat with it. Here comes the con(s).

Non-DI engines have the injectors in the intake channels, and spray the intake valve’s backing as it opens into the cylinder. This happens with each intake stroke, “washing” the intake valve with fuel. You have, I am sure, seen the Chevron with Techron and like commercials about it having additives which keep valves clean. This is great for NON-DI engines. Why the valves need cleaning is due to 1970’s legislation to handle pollution. Exhaust Gas Recirculation (EGR) and Positive Crankcase Ventilation (PCV) are 2 things required by law in the US (and many other countries) to prevent pollution. EGR pipes unburned fuel and particles in the exhaust, back into the crankcase to prevent catalytic convertor congestion and failure (things like unburned fuel, impurities in the fuel, water vapor, CO2, and oil). PCV takes crankcase vapors (mainly just oil particles and the EGR stuff) which is under pressure and pre-1970’s was just vented to the atmosphere, but now is redirected through a valve system which has a rough collection system that attempts to pull the largest particles from the air in this, and separate them out and allow them to drip down into the oil filter to be collected (if bad) or allowed to be cleaned and returned to the oil pan for engine lubrication – the particles too small to collect are mixed with fresh air coming into the engine just above the intake valves and shot back into the engine to attempt to re-burn them properly.

As you can imagine, the particles will collect on all parts of the intake, turning into sludge eventually and oozing into the intake, where it eventually is burned away during combustion. The problem happens with DI engines – the injectors shoot fuel DIRECTLY into the cylinders and don’t wash this gunk off the back of the intake valves. As such the gunk builds up here but since it’s so close to the cylinder, the heat bakes the gunk into carbon deposits which build up slowly over time. These deposits eventually become so heavy that they affect the airflow into the cylinders, making them move in unexpected patterns, or in very bad cases, not enough air is pulled in as the ECU is expecting, either way the result is too much fuel to the air ratio, or uneven mixing of the fuel, which robs engine power, can cause rough idle, and eventually cause Check Engine Lights (CEL’s) due to misfires (especially when the engine is cold). This causes a negative spiral, where the even higher amounts of unburned fuel due to the Carbon Build-up (CB) makes even more unburned fuel be re-circulated and these richer deposits speed the buildup on the backs of the valves further.

A few things are done by people to correct this.
- Carbon Cleaning – the top of the engine is pulled apart, intakes and valve covers are pulled, and the heads removed, then a Dremel or similar tool is used with a fine grain grinding bit are used to grind the carbon off the intake runners, the intake air flaps, and the backs of the valves. This is usually done around every 30K miles by those wanting to be sure they have the power and performance of the car unaffected.
- Catch Can – This is a 3rd party development, which partially bypasses the EPA mandated pollution measures mentioned above. It basically goes in-line with the recirculation of the gases before they hit the intake, comprising of a separate filter system that more aggressively captures and holds the particles the stock system doesn’t handle. The difference here is that the aftermarket solution doesn’t drop this into the oil, it holds it in the can, and you have a drain at the bottom where every 5-7K miles it needs emptying. Due to this being “bad stuff” from inside the engine, it cannot be disposed of easily, and is best poured into old oil containers and taken to a recycling place like Schuck’s or your local recycling transfer station, it’s mainly oil, water and fuel, so it can go into oil recycling.
- Methanol Injection – Typically referred to as “Meth” it’s been around a LOT longer than the illicit drug, and is basically a raw form of octane. What it’s used for is to both cool the incoming air (making it denser and therefore holds more oxygen for combustion) as well as boost the octane rating, which equates to more power. Methanol is mixed 50/50 with distilled water, and uses a special tank to hold it in, with its own pump and delivery system. The methanol is injected into the air intake around the throttle body, misting the incoming air. The methanol mist in the air cools it through evaporation, and since it’s a combustible liquid, it helps take place of the washing that non-DI engines get, by coating the backs of the valves and pulls the deposits into the fuel system rather than it baking and hardening there, as well as giving more horsepower and performance out of the car at the same time. Methanol is not very expensive, but is dangerous due to high octane and ability to burn, hence mixing 50/50. A typical use system will go through a small (1 liter) tank every 1-2 tanks of gas.

One of the things I didn’t mention (as it didn’t pertain to your car) is that Forced Induction (FI) engines are not as susceptible to this, the reason being the much higher compression and thus higher cylinder and valve temps if you do get it out and run it for at least 10-20 minutes at normal running temps.

Newbie123

Hi Raj99,

Incredibly informative. So far, at 125K miles I have done little more than run an occasional bottle of Techron in the tank. I do change the oil every 5-5.5K miles. Unless I don't solve my IMRC problem on Tuesday when I put the new position sensor on, I will become intimately familiar with the exact amount of carbon buildup on my intake valves. If I have any luck at all, my intake says on for now.

That leads me to ask you, whats your preferred maintenance plan to try and prevent carbon buildup? Also, would like your thoughts on to flush or not flush the sealed transmissions.

Thanks for sharing all of your knowledge.

Jay

Frotiss

Hi I have a 2008 A6 I change my oil about 500 miles ago I use Mobil1 I look at the oil stick and it looks dirty dO you think I have a oil build up should I get the Intake manifold clean or try the Seafoam Thanks

raj99

Dirty oil, oil build up, manifold cleaning??? you seem to be mixed up here.

If after you changed your oil and you checked your oil at around 500 miles, and it's very dirty, that may mean that you might not have such a great filter installed as well.

Get yourself a good quality oil filter (i.e. Wix, Mann, etc...) and then make sure you use good quality oil and lastly, if you are still getting dirty oil, I would recommend you send your oil out for examination to ensure that you don't have metal or other substances in the oil...since that could mean FAR bigger issues that simply dirty oil.

Blackstone Labs

Frotiss

Thanks a million

haloguy628

Synthetic oil will become dark brown almost immediately after change. The viscosity and additives are still there, so don't worry. If you need reaffirmation then pull couple of milliliters out and send it for analysis.