Fuel Injection System: A Work in Progress

fuel injection  DSC07241 200x153Gear case (3)All of the Volkswagen, Audi and Porsche cars all use a fuel injection system manufactured by Bosch. This article is only about gasoline fuel injection systems. And the concentration is more about what goes wrong than how it works. This body of information is rather pointed at the more technically spirited reader, and many terms may be unfamiliar and remain unexplained to the novice. Maybe an Index of technical terms will follow some day. For now, there is the Internet, knock yourself out. My apologies, I just don’t have enough time and space, either on this page or in my mind. There are many sub chapters involved here, since the information is so extensive. Sorry to make you click so much. This chapter is not meant to bum anybody out, just to inform to you of the facts so the repairs are understood and appropriate action can be taken.

When we mention the word “warranty” in this section, we are talking about the factory warranty and any extended warranty the factory may have on some of the high failure items. We are not talking about the aftermarket warranties that many customers purchase when they buy their car used. Your aftermarket extended warranty may cover some of these repairs, but our Knowledgebase refers to the factory warranties. And we will update this section as time pans out the problems. Call you Service Advisor for clarification if you need to. Have your policy handy. Every one is different.

fuel injection 150x105-217The first three systems from 1968 through the 70’s are lightly covered in our page on Early Engines.

Any fuel injection system is all about getting the precise amount of fuel mixed accurately with the precise amount of fuel. The reason it works so much better than an old time carburetor is not just the accuracy, it is the placement. German fuel injection system design has all been about injecting the fuel right above the intake valves, and recently directly into the cylinders. They have never really had a fuel injection system that had throttle body injection, which is just replacing the carburetor with another mixing device in the same location. Bosch has made them, but for other brands of cars. Throttle body injection has not been on any VW or Audi products.

A variety of methods have been used for measuring the air and injecting the fuel. Some have reincarnated in more reliable forms. Measuring manifold pressure is one of those. The original Type III D Jetronic inductive pressure sensor morphed into the MAP sensor of the Audi 5000 Turbo, then into the quartz crystal MAP sensor inside a Corrado ECU. The air flap of the 1975 Bus and Bug L Jetronic turned into the hot wire and then hot film MAF sensors of today. The first series of MAF sensor had many issues. With many improvements, modern MAF sensors are not known to fail. Every modern fuel injection system uses a combination of sensors to calculate the air intake volume, and they do it well.

From the outset in 1968, fuel injectors were electric, with a signal that varied in tenths of a milliseconds to open and close them. This soon went to 100ths of a millisecond, and now multiple pulse injectors venture into the microsecond range. Just the CIS K Jetronic technology had injectors that opened continuously and just sprayed. That CIS turned electronic with CIS E, but was then abandoned mostly in the 1988 model year by Volkswagen. VW changed to the Digifant injection in 1988, although Motronic CIS continued through the 16 valve series. Audi went to electric injectors in most models, but kept CIS though the end of the 5 cylinder 8 valve turbo motors. Every fuel injection system since has had pulsed electrically operated injectors.

TFSI & FSI Fuel Injection System

In this fuel injection system page, we are talking about one series of motors: the TFSI and FSI engines the came in the VW and Audi models starting in 2005.5. The CBEA motor started in 2008 and a couple of models, then in 2009 for most cars. Open your hood. The moniker is right on top of the motor. Many parts are under warranty and/or extended warranty, for now. Fuel pumps, camshaft & lifter, you may need them. Every model has its exclusions, and we have to run your vehicle’s VIN at Karmakanix to tell you what your warranty status may or may not be. This article will not go further into the warranty status, as that will change over time. Soon all these engines and parts will be long past warranty. These problems may look entirely stereotypic, most of them are entirely avoidable. Keep them from failing on your dime. There are just a few other uncommon fuel injection system repairs that we have had to do on the FSI motors. A couple of pressure sensors and some electric fuel pump control modules. But rather than elaborate on a rare bird, let’s cut to the chase. The repairs you have to pay for, warranty or not.
Gear case (2)Karmakanix Knowledgebase Information on TFSI & FSI Fuel Injection

Oil Consumption Issue: PCV & Carbon Buildup

fuel injection system pcv DSC07444 120x92A seeping PCV system can cause your engine to build up carbon. This carbon buildup problem is a serious issue and no doubt will become more so as the engines age. High oil usage on these 2.0T engines leads to a much faster carbon buildup in the intake system. Eventually the carbon disturbs the air swirl patterns as the air enters the cylinder, causing poor combustion of the stratified fuel charge. After setting DTC codes for mild misfires when cold, eventual the engine becomes undrivable. Attempting to drive the earlier motor will definitely destroy it. However the power is so low, and the banging noise is so loud, nobody tries to drive them. Sometimes the critical change occurs within weeks, sometimes months, never years. We definitely recommend that you read this link if you have been experiencing oil consumption of over about 1 quart per 2000 miles.
Gear case (2)Karmakanix Knowledgebase Information on Carbon Build Up

Gear case (2)Karmakanix Knowledgebase Information on Carbon Cleaning

Have you wondered yet what these customers are going to do once their cars get past the extended warranties? We have. Our best advice is consistent 5000 mile oil changes, regular fuel filter changes, and keep track of your oil consumption. We consider that to be normal maintenance procedure for your TFSI engine. So should you. Call your Karmakanix Service Advisor, you are likely to get a different story than from the dealer. We are on your side.

Gear case (3)