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N/A s3 Got no boost...any suggestions?

slowcoach3 Sep 30, 2012

  1. slowcoach3

    slowcoach3 Active Member

    Hi all, my 2000 APY S3 is really doing my head in!!
    I have no boost, car feels like an N/A S3 there is still a small amount that makes the noise into the B5 TIP but none that you can feel while driving. If your driving in 4th at 40ish then bury your foot normally the torque puts you back in seat now it very very slowly climbs the rev range until maybe 5k then picks up a bit.
    So far I have
    Scanned for codes...Nothing there
    Electronicaly disconected the N75....No change
    Disconected MAF....No change, neither better or worse
    Stripped off all main boost hoses, TIP, DV etc in search of leaks...nothing found. Car idles correctly as well.
    Logged MAF in 3rd and 4th highest output was 177gs off the top of my head worked out at 220bhp, was 269bhp 3 weeks ago
    Unfortunately can't log boost request etc as only have unregistered lite VCDS.
    I checked the turbo, very little play but quite alot of oil on the blades and also in the red charge pipe,
    Any suggestions or ideas welcome as I'm stumped!
  2. Dani_B19

    Dani_B19 Audi-sports own special child.

    Have you logged fueling, timing etc to see what their all doing? Have you checked all the lower intercooler boost hoses? Checked all the pcv pipework?
  3. Andrew@A.L.D

    Andrew@A.L.D May add NOS to 600+bhp S3.

    • Rough Running At Idle: MAF, Ignition Coil, Spark Plug, VAC Leak, O2 Sensor, TB, CTS
    • Missfires under Boost Flashing CEL: Ignition Coils, Spark Plugs
    • Running Rich: Boost Leak, MAF, O2 Sensor, Coolant Temp Sensor
    • Running Lean: VAC Leak, MAF, O2 Sensor, Fuel Filter
    • Low Boost: Limp Mode, MBC, BOV, DV, Boost Leak, N75
    • High Boost: MBC Setting, N75, Spark Plugs, Ignition Coils
    • Cold Start Problems: MAF, Spark Plugs, Fuel Pump Relay, CTS
    • Poor Gas Mileage: MAF, CTS, O2 Sensor, AIT Sensor
    • Cat Efficiency Below Threshold: Down pipe, CAT, Rear O2, RACE FUEL
    • No Start: Battery - ECU, Fuel Pump Relay, Ground
    • Start For 1 Second Stall: Immobilizer
    • Overheating: Waterpump, Thermostat, Head Gasket
    • Oil in coolant: Oil Cooler, head Gasket, Water Wetter
    • Dies While Driving: Timing belt, Boost Leak, MISC
    • Shorts To ground CEL: Fuel Pump Relay, Bad Grounds
    • Oil in your IC/IC piping: Check your PCV system
  4. Prawn

    Prawn My other car is a MINI!!!!

    Sounds to me like it's running on actuator pressure mate. If it's picking up a tad at 5k or so that's most likely a hint of boost creep causing that.

    I'd check the wiring into the N75 plug, it seems to be getting more and more common for the wiring to fail inside the insulation. Caused me no end of trouble on a trackday!
  5. S3 TAM

    S3 TAM Pocket now empty

    +1 on this.

    Check N75

    Did u take the pipes off when changing sparks. May have connected it up wrong.
  6. Dani_B19

    Dani_B19 Audi-sports own special child.

    What boost is it makig?
  7. slowcoach3

    slowcoach3 Active Member

    Cheers guys..
    I can't log boost/n75 cycle as only have basic vcds which sucks.
    Everything was correctly disconnected when changing plugs, I have also gone over every single hose coming off the DV, N75 and TIP all seems ok.
    Prawn, the wiring for the N75 if I put a volt meter across this would it give any useful information? Can't do it tonight as I'll need to borrow one from somewhere...If thats actuator psi then would that limit faults to being n75 related?
    Sooo many questions and options lol

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