When I had my injectors cleaned, the guy said he found sludge inside the injector filter baskets. However, when you have a tolerance of 1 micron any amount of carbon buildup can affect the injector flow in a big way. Fortunately the buildup is not near as dramatic as the on intake valves.

In our cars the fuel injector heads are exposed to the combustion chamber so they can get carbon on/in them just like our intake valves. There have been a few documented cases of this. Rough cold start - The cold start cycle was extremely rough with RPMs approaching 2000Įngine damage - Possible in the event of a fully clogged injector. Surging idle - Idle was constantly fluctuating I’ll start with my recent symptoms and the diagnosis that led me to cleaning the fuel injectors.

There’s not much information specific to the RS4 available on the subject so this is a good place to start. Justin suggested starting a thread about FSI fuel injectors and the potential problems caused by carbon buildup on/in the injectors.