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Audi and the carbon Build up woes

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Old 06-17-2017, 05:38 AM   #1
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Default Audi and the carbon Build up woes

So I am new to the world of Audi and before purchasing mine was told that one of the negatives of these cars is the carbon build up that can eventually become very costly to deal with. Can one of you long time Audi owners elaborate on your experiences with carbon build up in your cars and what you do to avoid/prevent it from happening? I've heard its something you live and deal with in general?

I mean is this something that usually happen after the 4 yrs or 50,000 miles warranty expires or how often does the build up get to a point that needs attention?

Last edited by edle; 06-17-2017 at 05:44 AM.
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Old 06-17-2017, 06:25 AM   #2
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There is a pretty good discussion of it here:

https://www.audiworld.com/forums/a4-...-pipe-2917378/

It seems the best thing one can do is use a high-quality detergent gas like Shell Nitro.
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Old 06-17-2017, 06:28 AM   #3
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Thanks for the tip, I've already only used Shell Premium for the past 10+ years only so should be good there.
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Old 06-17-2017, 08:45 AM   #4
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Gasoline quality has nothing to do with the carbon build up issue. Carbon builds up on top of the intake valves because with direct injection fuel is injected directly into the cylinders. Carbon migrates to the coldest surfaces and the intake valves are the coldest. Since fuel never touches the valves the carbon keeps building up till it starts robbing you of power and fuel economy. With port injection fuel is sprayed into the intake manifold and washes over the valves as it enters the cylinders. Carbon can't build up.

There's really no answer to keeping the valves clean other than running the car hard once in a while to heat up the valves and burn some of the carbon off or just wait till approx 40k miles and have the carbon media blasted blasted off with something abrasive like ground up walnut shells that's abrasive enough to do the job but harmless to the cylinders because invariably some will enter the cylinders but will harmlessly get burned off.

Porsche invented this technology because it's so efficient. Direct injection atomizes the fuel better at 1600 psi vs port injection that sprays fuel at 50 psi. Porsche owners just chalk the cost of regular cleaning up to regular maintenance. The rest of us take issue with paying $500+ to have this done every 40k. Oh well, DI is the reason cars are getting much better fuel mileage that they used to.
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Old 06-17-2017, 09:04 AM   #5
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I don't have a problem spending $500-ish to have this done every 40K, even every 30K is fine with me. I just didn't know if such "carbon build up cleaning service" was available. What is this service called and would my local dealership offer it?
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Old 06-17-2017, 09:15 AM   #6
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I don't what it's called but your Audi dealer offers it.

A lot of companies offer media blasting for carbon build up.

Here's a link to 034 motorsport and what they do. https://store.034motorsport.com/serv...d-engines.html

$500 doesn't bother me either since I put about 5k miles a year on my cars I will not have this car in eight years. Probably won't have in two years. A B9 S4 is inevitable

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Old 06-17-2017, 09:31 AM   #7
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Quote:
Originally Posted by up-n-coming View Post
Gasoline quality has nothing to do with the carbon build up issue. Carbon builds up on top of the intake valves because with direct injection fuel is injected directly into the cylinders. Carbon migrates to the coldest surfaces and the intake valves are the coldest. Since fuel never touches the valves the carbon keeps building up till it starts robbing you of power and fuel economy. With port injection fuel is sprayed into the intake manifold and washes over the valves as it enters the cylinders. Carbon can't build up.

There's really no answer to keeping the valves clean other than running the car hard once in a while to heat up the valves and burn some of the carbon off or just wait till approx 40k miles and have the carbon media blasted blasted off with something abrasive like ground up walnut shells that's abrasive enough to do the job but harmless to the cylinders because invariably some will enter the cylinders but will harmlessly get burned off.

Porsche invented this technology because it's so efficient. Direct injection atomizes the fuel better at 1600 psi vs port injection that sprays fuel at 50 psi. Porsche owners just chalk the cost of regular cleaning up to regular maintenance. The rest of us take issue with paying $500+ to have this done every 40k. Oh well, DI is the reason cars are getting much better fuel mileage that they used to.
So this would be an issue with any direct injection engine, right?
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Old 06-17-2017, 09:35 AM   #8
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Quote:
Originally Posted by lowjdml View Post
So this would be an issue with any direct injection engine, right?
Yes all except Lexus's 3.5 liter DI engine. They put one fuel injector in the intake manifold just to wash a bit of fuel over all the intake valves to keep them clean. Seems to work well.

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Old 06-17-2017, 09:37 AM   #9
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Quote:
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Gasoline quality has nothing to do with the carbon build up issue.
Nobody said it does. Using a good detergent gasoline will help clean the carbon from the valves.
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Old 06-17-2017, 10:16 AM   #10
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Doesn't changing oil more often than 10k help?
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