I need injector education!

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  • panzerwagen
    S2Forum Maniac
    • Feb 2004
    • 900
    • Country: United States

    #1

    I need injector education!

    What happens when you install a set of injectors that are say 29lbs at 1-3ohms into a car that's a running stock fuel delivery system that originally came with 17lbs injectors at 1-3ohms? Flooding? Rich running to the point of terrible fuel economy? Possible damage to the cat? Will the stock fuel regulator keep this from happening? Will it starve the injectors if the regulator controls the pressure to stock specs?
  • Doug_RS2
    S2Forum Possessed
    • Jul 2003
    • 3847
    • Home: Scotland Current: England

    #2
    lambda should adjust the duty cycle of the injectors so you get correct mixture on idle and part throttle. The ECU doesn't use lambda (on our cars) at WOT so you rely on the maps - and these will be wrong so you will run rich in that condition. There is only a certain amount of adjustment in the maps so you run the risk of going off the scale and this will throw a fault code - BTDT.

    The fuel regulator will just keep the fuel pressure in the rail at a constant 4bar(for aby - 4bar FPR) above the manifold pressure (on boost) i think on idle (vacuum in manifold) it drops the fuel pressure to 3.5 bar.

    Does this make sense - I think this is correct.
    S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

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    • audiman
      S2Forum Freak
      • Jul 2003
      • 4827
      • Country: United Kingdom

      #3
      Thats correct Doug. Been working all this out recently The car will run very rich at WOT, so dont use WOT until the car has had the ECU adjusted to suit your new injectors. It will be dumping excessive fuel into the cat which 'could' cause damage. The car will be fine at part throttle as Doug already mentioned
      sigpic
      Tom C - www.rcmr.co.uk
      Audi UR Quattro
      Audi 100 C3 2.0 5 cyl 115ps
      Audi S2 - 07k engine project aiming for 800ps
      Audi B5 RS4 645ps 911nm

      Comment

      • Floddy
        S2Forum Addict
        • Dec 2003
        • 222
        • Country: Sweden

        #4
        Originally posted by audiman
        It will be dumping excessive fuel into the cat which 'could' cause damage.
        Worse, you could end up with a fooked up crankshaft.

        If you get way too much fuel, it could stick onto the cylinder walls, and get down into the oil pan. Oil with fuel in it doesn't lubricate very good =/.
        Red cars are the fastest ones...
        - Team Irry -

        Comment

        • audiman
          S2Forum Freak
          • Jul 2003
          • 4827
          • Country: United Kingdom

          #5
          Good point mate
          sigpic
          Tom C - www.rcmr.co.uk
          Audi UR Quattro
          Audi 100 C3 2.0 5 cyl 115ps
          Audi S2 - 07k engine project aiming for 800ps
          Audi B5 RS4 645ps 911nm

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