By Christopher A. Sawyer
The Virtual Driver

(September 30, 2015) I believe there are a couple of reasons Volkswagen's engineering staff chose to create a software cheat that defeated its diesel-powered vehicles’ onboard emissions system.

The first is a combination of pride and pressure. Pride in the German nation’s seeming mastery of technology, and pressure from VW’s centralized management structure to create a passenger car diesel engine that could meet U.S. emission standards and produce hybrid-like fuel economy numbers.

Once Toyota used TRW Power Systems Division technology to create the first production hybrid, everyone else was late to the party. They could not create a unique vehicle with hybrid power as Toyota had already done that with the Prius.

What the German automakers could do was grab the best available technology, combine it with years of experience in the production of passenger car diesel engines, and create a class of automobile and light truck that did not demand a sacrifice of style, size, space or driving fun, all while returning exemplary fuel economy. No one was more interested in this stratagem than VW.

Creating a system that would meet U.S. emission standards was difficult at best. The LEV II Bin 5 standards were the toughest in the world, and became the standard around which the rest of the world would built its future diesel regulations. This gave the automakers an incentive to meet or exceed the U.S. standards. And VW, under the autocratic control of CEO Dr. Ferdinand Piech, had an added incentive to prove itself better than its home town rivals as it was locked in mortal combat with both Mercedes and BMW.

This placed tremendous pressure on the engineering staff and component suppliers. Nothing but the best would do. However, that best also had to be affordable, and applicable to the then-current diesel family. In addition to the common-rail technology borrowed from Fiat, engineers added direct injection and turbocharging to give better fuel metering and greater power. Pretty soon every German automaker had its own version of this layout.

What they didn’t seem to have, unfortunately, was VW’s penchant for avoiding carbon buildup  on the valves and within the intake manifold. Mercedes and BMW diesels suffer from significant carbon deposits, while VW’s do not. (Ironically, VW’s gasoline direct-injected motors have the deposit problem its diesels didn’t.)

Port injection (so named because it injected the fuel into the intake port), washed some of the oil and contaminants from the backs of the valves, as well as from the ports and intake manifolds. Direct injection bypasses this route to inject a precisely metered amount of fuel directly into the combustion chamber. There is no opportunity for the fuel and its additives to wash the carbon from these surfaces.

In addition, tougher emission standards put an emphasis on increasing PCV regeneration in the engine. That is, the portion of unburned fuel, exhaust gasses and oil vapor was increased to prevent this brew from exiting through the tailpipe. And this is where VW’s second reason for this deceit arrives on the scene.

With the increase in PCV use, the carbon deposits are mixed with a viscous vapor to create a baked-on goo that coats the valves, heads, and intake manifold. Removing this coating currently requires the removal of the head and intake manifold, and walnut shell blasting of their surfaces until clean. This costs from $1,000 - $4,000 per vehicle. Researchers claim it is not unusual to have 1/4-in. deposits baked onto these surfaces, and for the valves to be “welded shut” by deposit buildup. Yet VW’s diesel engines seemed to be immune to this process. Now, it appears, we know why.

Keen to avoid the power robbing deposits that harm both power and fuel economy, the decision was made to defeat the emission controls under most conditions in order to save the company and its dealers from being inundated with requests for engine cleanings.

Though criminal on its face, the decision was logical, and designed to save both VW and its customers money and the hassle of cleaning of the deposits. Removing the malware and rewriting the code will allow the engines to operate as designed, but undoubtedly will increase engine deposits and, ironically, engine-out emissions.

The Virtual Driver