Audi Carbon Cleaning (Walnut blast)

If you own an Audi, chances are that you have heard of their infamous carbon buildup issues. Most Audi models from 2008 onwards, and many earlier models are subject to this issue. This is because increasing emissions legislation lead to manufacturers commonly implement direct fuel injection technology, referred to by Audi as FSI, TSI, or TSFI, and in the greater market, GDI (Gasoline Direct Injection). While this article is not about this technology, some basic knowledge is required to understand why carbon buildup is a major downside of it. 

What is Gasoline Direct Injection?

Gasoline Direct Injection, or GDI is simply a system that injects fuel directly into the combustion chambers. Early combustion engines used carburation as a method for fuel delivery, but this is no longer used in modern engines. If your engine is not using GDI technology, it is likely to use port fuel injection or PFI. PFI does not inject fuel directly into the combustion chamber, but instead into the intake manifold where it is mixed with air before even entering the combustion chamber. This means that the intake valves that regulate air entering the combustion chamber are constantly being cleaned by the fuel. In engines with GDI, this cleaning does not take place. GDI technology grants greater flexibility on fuel injection quantity, timing, and duration, thus improving fuel economy. 

What does GDI have to do with carbon buildup? 

When the intake valves are not being cleaned by fuel, carbon will build up on them. This carbon is due to crankcase vapors being re-circulated back through the intake via the PCV breather system to be burnt off. Over time some of the vapors will condense on the intake valves creating a thick stubborn buildup akin to asphalt or tar. 

Symptoms of excessive carbon buildup

While your vehicle can still function, even with moderate carbon buildup, a distinct decline in fuel economy and performance is present. In severe cases, the engine will run very poorly and may even stall, especially during the first cold start of the morning. As carbon buildup is a slowly progressing condition, often taking over 50,000 miles to show symptoms, drivers may not notice their vehicle acting strangely. However, following a carbon cleaning service, immediate improvements can be felt. Your vehicle, will run better, accelerate faster, and consume less fuel. 

Audi Walnut Blasting in Seattle

Doing a quick internet search, you may notice many fuel additives that claim to cure carbon buildup. While there are many real benefits to fuel additives, in GDI engines, cleaning carbon buildup from intake valves is not one of them. This is because none of the fuel will reach the intake valves to clean them. There are two main methods we implement to perform carbon cleaning. In very light cases of carbon buildup chemical cleaning can be used. This involves injecting a very concentrated cleaning chemical directly into the intake tract while running the engine, this mimics how PFI functions and as such, reaps its cleaning benefits. Unfortunately, carbon buildup can be very stubborn and in moderate to severe cases, a physical media blasting is needed to adequately clean the buildup. While most industrial media blasting uses, sand, ceramic, metal, or glass media, the most popular choice for automotive applications is to use walnut shell media. This is because walnut shells are hard, yet will not damage any internal engine surfaces. Great care is taken to prevent any media entering where it shouldn’t, however in the case that it does, the organic matter will not damage anything. While walnut blasting can be a pricier alternative to chemical carbon cleaning, it is by far the most thorough method for cleaning carbon buildup, and will leave a like new finish when completed. At Precision Motorworks, we have invested in a high quality professional grade walnut media blasting machine in order to offer the best service possible. We’ve opted to skip diy-oriented options such as brush and hand cleaning methods.

What can be done to prevent this issue?

While carbon buildup is unfortunately an unpreventable side effect of GDI technology, a few things can be done to help mitigate issues. Firstly, making sure that your PCV system is in good working order is key, an inefficient or failing PCV system will cause buildup to occur at a much accelerated rate. Secondly, choosing a high quality fuel, certified by TopTier will help slow buildup. While this may seem counterintuitive, since the fuel is not cleaning the intake valves, the benefit actually comes from the way the additives within the fuel interact with the engine oil. If you think your Audi may be suffering from carbon buildup issues, let our Audi specialists help you get the best performance and life out of your engine!