Magazine for the auto service professional
Issue link: http://asp.epubxp.com/i/636156
54 | February 2016 (the multiplicative value is the fuel trim variation at all other engine speeds but idle either adding or removing fuel). So using the scanner I went to the VW measuring block that would show me the additive and multiplicative (fuel trims): group 32 in this case. With the car at idle the additive number was high at +7.9%, and the multiplicative was OK at 0%. Everything was pointing to a vacuum leak, but these engines have very few vacuum lines, and the ones it did have were connected and made of hard plastic with good connectors that don't often fail. I was starting to think an injector O-ring or the lower intake gasket could be the con- cern, so I attached my smoke machine to the intake snorkel. To my surprise there was no smoke at all under the hood. The engine was tight and sealed. The only spot that revealed any smoke was the tailpipe and the right rear wheel area. Yes, the right wheel well had smoke coming out of it! This didn't make a lot of The Tech Bench Again, these VWs don't typically have EVAP leak issues from the lines or connectors. The scanner showed that the VW was running lean at idle and adding fuel. The same data group after the repair and a city stop-and-go road test verifes the repair.