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FSI and TFSI Fuel Injection

Gear case (3)The recent FSI injection systems deserve to be explained. Because that is the only way one can comprehend the massive failure rate of the first entry technology. Hate to say it, but at Karmakanix, we have been steering potential used car buyers around the first version of the Stratified Fuel Injection from 2005.5 through 2008 in VW vehicles and 2005.5 through 2007 with Audis. Basically, all the first series that have a timing belt. The second series driven by a timing chain system has all the same problems, but an extremely lower failure rate. TFSI engines are the first belt driven 4 cylinder turbo version. FSI are second series 4 cylinder turbo motors, and the 6 cylinders without a turbo. Different monikers, same system. First, the explanation.

The FSI injection systems start with a power controlled fuel pump in the fuel tank. Unlike earlier fuel pumps that just turn on and go, this fuel pump has a power control. When viewed on an oscilloscope one sees a series of jagged scribbles along the current amperage sine wave. Normal readings in measuring value blocks, or MVB, are between 40% and 50% current. As the fuel filter slowly clogs, the rate goes up over 60%. At some point, the pump is doomed to overheat and fail. Mostly caused by fuel filter contamination. Mostly prevalent with customers who bought cheaper fuel. Fuel filters had been removed from factory recommended services back in 1993.

pcv fsi injection DSC07441 120x92After a boatload of fuel pump failures in the first FSI injection systems, the manufacturer saw fit to include a fuel filter in the major services of the future engine series. Good thinking, but what about the motors that had the problem first? Oh, they were already sold, and out of warranty. Not Really! VW and Audi were later required to give an extended warranty on this high failure rate fuel pump. Then they decided to recommend the fuel filters. In fact, any technician who knows the system can check the status of your fuel pump power readings, and recommend a fuel filter change if need be.

The electric fuel pump supplies a high pressure fuel pump that runs off a lifter at the end of the camshaft. The high failure rate of this system destined the first series of FSI motors to extended warranty status. Karmakanix has replaced quite a few of these cams and lifters, although the vast majority of the early problems with FSI injection were sent to the dealer for warranty work. These early cars are now out of warranty and the customer must now foot the bill if the system fails. If you show up with the yellow Check Engine Light on (MIL), and a Diagnostic Trouble Code (DTC) for high pressure fuel, the camshaft wear out issue is likely what you are up against.

The hardening of the 3 corner cam lobe and of the tiny lifter that drives the high pressure fuel pump is just a few thousandth of an inch deep, and once the wear really begins, the cam and lifter will fail rapidly. There could be a relationship with the dealer recommended oil change interval of 10,000 miles. Thus only 9 changes before the car crosses the magic 100,000 barrier? Or is better metallurgy required? We believe that the wear reduction from Molybdenum Disulfide additives may be the extra protection all of these FSI series engines require to avoid the camshaft and lifter wear problem. Karmakanix recommends the use of Liqui Moly MoS2 additive every 4th oil change.

Gear case (3)