[Caddylackn]

With some stupid tdi tuning issues (boost creep) and codes and flashing glow plug light, my gas mileage did not appear to go up after these mods and actually went down. I did all of those aero mods in the last two posts at about the same time.

I was also going into limp mode at full throttle, which I do for short times once a day to cleanout carbon and preventing wastegate from sticking. I replaced my vacuum line to the turbo wastegate and the limp mode went away. The hose was not very stiff and I think it was collapsing.

I did notice, that after these last aero mods my coasting ability went up, higher terminal speeds on hills or longer coasts on my commute, so the aero mods worked.

I replaced my MAF and my gas mileage improved almost 10% so that was some of it. I still get mild boost creep, where holding a constant throttle will slowly build boost and increase fuel use, as seen with the Scan Gauge II. I think this may be from having almost no back pressure (straight pipe) and a mild tune designed to increase boost. So while driving, you just constantly stare at the boost gauge and try to keep it below 18 psi (absolute) when cruising up slight grades.

I still have air bubbles so I am replacing the fuel line to the injector pump. VW wants like $200 for the pre-formed 2-foot long fuel and return line from the filter to the injector pump. I found a substitute line (clear) to use. You need to have at least one section of clear so you can check for bubbles.