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high fuel consumption (act maf readings too high)

navicx Sep 2, 2012

  1. navicx

    navicx New Member

    Not sure if I'm in a right tread. Recenly I have purchased 06' audi A4 with 1.9 tdi engine (BRB). Before that i owned a 99 passat with 1.9 AJM engine. Both 115bhp, both PD. Everything seems to be perfect with audi, I'm driving same style, same route, but it uses more fuel! Diference is not big, but about 1liter / 100km more (about 8-10 im. mpg). Audi has DPF, has 205 width wheels instead of 195, but fuel consumption difference still is too big.
    Logged some data with vcds and compared two cars. One thing what is concerning me is that MAF readings of audi's is about 100-150 higher then specified. ( if more air is in, more fuel has to be added right?)
    Should i start searching for boost leak or may be something else is the problem ? EGR duty cycle is 99.6 when accelerator on the floor. No fault codes. Any other opinions why high fuel consumption?
    Thank you

  2. PAULF

    PAULF Active Member VCDS Map User

    Seems like it's a bit sluggish. too.

    I don't know the PD engine, but I believe they use the variable vane turbos

    It could be your turbo actuator rod length too long. I've had all sorts of grief on one of my 2.5 Tdi's that turned out to be the rod length too long. This increased fuel economy, decreased low down torque, and acceleration.

    Have a look at my thread 2.5TDi Sluggish which also links into a good 1.9 turbo logging thread.
    Last edited: Sep 3, 2012

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