Chemical carbon cleaning

A6 All/ S6 All
#1

I know this has been covered all over the web but i thought i would share some personal real world experience with regards to chemical carbon cleaning.

I witnessed a B7 RS4 undergo 3 treatments of this solution by BG products - https://vimeo.com/3989681

Once the treatments were completed the manifold was removed after a 1000 miles or so and the results were really quite noticeable and impressive however there was a really big issue.

The cleaning fluid took the path of least resistance through the manifold and only one of the inlets was clean and the rest were pretty much untouched. The conclusion was that if the fluid could be diverted into each inlet port the results would be really rather good.

My immediate thought was could something like a nitrous oxide jet be installed over each port and be fitted with a blanking plate so that they become a permanent fixture for preventative maintenance use?

We seem to have some pretty clever guys here so thought i would put the idea out there.

#2

One thing you aren’t taking into consideration is that the carbon being cleaned has to go somewhere…that somewhere during this process is through your engine. One thing you do not want is a huge chunk breaking off and going into the cylinder and scoring your cylinder walls. When you clean the ports manually you aren’t letting all of the junk go through the motor. When you use media blasting to clean the ports your time is probably cut more than half and you’ll get amazing results.

You clever idea is really kind of a waste of time considering you can buy the tools to do a walnut blasting for less than $250. You might need to do the cleaning every 15-20k miles so hacking up your intake manifold and risking vacuum leaks or other issues would be kind of counter productive IMHO.

#3

Can you please provide some links to the walnut blasting kits/parts that would be best for our cars.

#4

I dont quite agree.

If the manifold was coming off to undertake a manual clean it would be a pretty simple process to modify the manifold whilst its off.

That way you are starting with a clean inlet and by using the chemicals on a regular basis of say 5k to 10k miles you wont be getting large chunks of carbon build up.

Buying the equipment to undertake the work yourself is fine if you are a competent DIY’er however a full carbon clean for the S6 in the UK starts at £750 or around $1200

#5

The most complicated solution is rarely the best one.

The hardest part of a carbon clean is removing the manifold. It’s not even that hard, it’s just finicky the first time. A friend wiht an RS4 got so good at it, he can have it off in 45 minutes now. Once its off the media blast method is so easy you will wonder why people make such a big deal out of carbon buildup.

Removing the manifold every two years to do a thorough carbon cleaning that actually works, and that you know works because you’re looking at it, is far superior to hoping a chemical clean is doing the job. The only beit of the chemical solution is that you don’t need to remove the manifold. The irony of this is that you need to remove the manifold to ensure it has worked thoroughly and properly anyway lol.

While the price may be 750 to 1200 pounds sterling to do a carbon clean in the UK, I think someone should spend their energy learning to remove the manifold and to use media blast method to carbon clean instead of trying to invent an injection system.

Don’t also forget that euroswagr’s other main point above is that this ‘solution’ may actually cause a boatload of other problems as well.

Finally, people with direct injection cars love to blame carbon buildup for all of their problems. It’s not that big of a deal. Sure it’s a top end limiter (the extent of which is actually FAR less than people think, as our extensive acceleration testing on this site has shown) but at the end of the day, most people who get a big ‘bump’ from doing a carbon clean are actually fixing other problems by accident that have nothing to do with carbon. My car ran the fastest ever stock 1/4 mile time for a B7 RS4…and it did so with 35,000 miles on it and never a carbon clean. When I got it cleaned, the acceleration delta was nominal at best. Mistro’s car did 1/4 mile testing week 1, carbon clean week 2, and 1/4 mile testing week 3. Zero change in performance results.

#6

That’s fine, it’s only my opinion, but how much does the IM you are going to possibly ruin cost to replace? In reality this probably needs done every 25-30k miles depending on how obsessed over carbon buildup the owner is and for the life of the car or the extent of your ownership 2-3 cleanings for a couple grand isn’t horrible for maintenance costs.

Don’t products like this usually kill or shorten O2 life, I’d hate to kill those and need to pull the engine on my S6, which if you aren’t a DIY would easily cost you a few grand.

People have been talking about and discussing a permanent fixture/cleaning system on the RS4 for years, but it must not make much sense to design and install. So that is why I think it just makes the most sense to keep it simple and continue with the options that are already there instead of trying to design something that may possibly not work that great in the end anyways.

In the end it’s your time, money and car…we just like to give an honest perspective around here. You aren’t thinking of anything we haven’t seen or heard before.

#7

Im in agreement with that sentiment.

Ive close to 90k miles on my S6 and have had several misfires faults over the years of ownership; every time i researched the fault the default reply was “carbon buildup” however it has always been something else (crankcase pressure and a failing battery so far).

Think I will stick with my regular “Italian” tune ups ;D

#8

I guess my thoughts were that most of these chemical treatments have a reputation for being snake oil however having seen the results firsthand i can say that the BG one can make a significant difference.

#9

most of the chemical treatments are snake oil. Most of them inject using the fuel system, and thus miss the carbon completely thanks to direct injection…the reason there is carbon buildup in the first place lol.

The rest as you note are flawed in execution. It’s like trying to invent a lazy way to do a job, which everyone loves (myself included) but if that lazy way causes problems, or is prohibitively expensive and complicated vs. a simple cleaning, sometimes you just have to accept some hard work (or cost).

As euroswagr mentioned, carbon cleaning isn’t needed every 6 weeks as some of the dummies on other sites will have you believe. It is also not $5,000 so it’s not that bad of a pill to swallow.

If I were you, I would find a BMW board in the UK, and find out what the 335i guys are doing for carbon cleanings. They’re a great resource because

a) they’re direct injection and suffer with carbon just like we do
b) there are millions of them
c) the cars are cheap, and with some being 7 years old, they’re even cheaper now so people won’t accept a 1250 pounds carbon clean (audi dummies seem to love to pay MRC or whoever double what they ought to because they like ‘prestige’ (even though the products are generally not that great i.e. Milltek, MRC port/polish etc.)
d) they’re owned by enthusiasts who are obsessive about stuff like this so they will figure out a way to fix carbon
e) they’re owned by young guys who tend to be cheap, so they find a cost effective solution at the same time

Those things mean they will probably know a BMW shop who does media blast carbon cleanings for about 600 pounds. If you get 2 done over the next 3 years, that’s the same as you should be paying in oil changes so it shouldn’t be too prohibitive.

#10

Sakimano said it best but I’ll add a little to it.

Intake induced chemical carbon cleaning had been used for years and years way before FSI. While it can do great things it isn’t as well targeted as a good on the spot cleaning. Chemical intake charge cleaning misses big parts of the intake and the Valves. At the speeds the air is allowed to travel at low rpm the air is on a almost constant fixed path. That path will do well for some valves and areas but not for all.

Also remember that if you push the chemical through the intake it’s going to carry that and any buildup in to the cats and past the 02s. Two things that you need to pull the motor on in a v10 to replace or service

#11

wow…also key!

save 1000 bucks every two years and spend $2,000 to pull engine for o2 sensor or de-cat. Yikes.