Advice on A4 1.8T

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  • skiffy
    S2Forum Enthusiast
    • Mar 2009
    • 136
    • Country: United Kingdom

    #1

    Advice on A4 1.8T

    So the S4 is gone and I managed to get the family schlag through it's MOT without much hassle in the end. So without an S4 to focus on I can maybe try sort all the annoying aspects of this much neglected car while I have to put up with it. It's a facelift '99 1.8T Sport (150)

    1. The idle. For a long time now it's had an uneven, misfirish type idle. It oscillates between 760-800rpm, you can see the needle bobbing up and down and there's a bit of a hiccup to the exhaust, in words it sounds like derrrrrrr der der derrrrrrrrrrrrr der derrrrrrrrrr Have checked coil packs and plugs. Could it be TB needs a clean? or a clogged breather pipe?

    2. Throttle control is iffy. In my S4 I could happily put it in gear and lift the clutch without touching the throttle and it would happily cost along at a steady pace. This one I have to give gas, and if I take it away it'll kangaroo. (once driving normally it's completely fine and pulls very strong). It also feels as if there's a lot of resistance to the engine turning over. It has a new battery but cranks quite slowly on startup (does always start but doesn't fire into life like it should) and when you turn it off the engine stops dead immediately. (and yes it has oil!).

    3. According to the dials the engine runs very cold. After a 40minute drive in to work this morning both coolant and oil gauges were reading just over 60. I replaced the coolant temp sender last year but made no difference.

    Any thoughts on the above? None of this is new, been like it for ages! but since it's not been my daily I've not done too much about it.
  • hunker7
    S2Forum Possessed
    • Mar 2014
    • 3487
    • Home: Latvia Current: United Kingdom

    #2
    If you haven't driven it for a while, give her a good blast down the road. I always notice my car running much smoother after a good motorway drive.

    I would also try and connect vagcom and see if there are any error codes.

    I think for oil 60 degrees is fine (might be wrong), in my S4 it ever barely moves when driving normally. As for temperature, thermostat is stuck open possibly?
    '93 Audi 100 Avant - R.I.P
    '92 Audi UrS4 Avant - SOLD
    '93 Audi UrS4 Avant
    '15 Audi A7 quattro 3.0 TDI

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    • silizium
      S2Forum Fanatic
      • May 2005
      • 95
      • Country: Finland

      #3
      1.8T and bad idle. Check breather hoses under intake manifold.

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      • andy10v
        S2Forum Zealot
        • Mar 2009
        • 5996
        • Country: Scotland

        #4
        Fault codes?

        Is a 99 cable throttle or drive by wire? If DBW there is a throttle body alignment process.

        Temperature could be thermostat.
        Current-2004 Impreza PPP wagon

        Sold-92 3B coupe-RS2+, 996s, konis, rear torsen, forged rods........
        Sold ABY-stock

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        • silizium
          S2Forum Fanatic
          • May 2005
          • 95
          • Country: Finland

          #5
          I think facelift 1.8T is always DBW

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          • skiffy
            S2Forum Enthusiast
            • Mar 2009
            • 136
            • Country: United Kingdom

            #6
            Last time I scanned there were no codes. If DWB and I pull the TB to clean it I assume I need to run the alignment procedure in vagcom when I put it back?

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            • ChrisG
              S2Forum Fanatic
              • Jan 2005
              • 68

              #7
              Silizium - not necessarily in the UK. Certainly all facelift quattro 1.8T ( AJL code 180bhp) were definitely cable.
              Temp is almost certainly the stat, I changed the sender ( easy job) and the gauge reads the same, on the bottom ! New stat is not quite so easy - unless you're doing the cambelt at the same time !!
              Irregular idle may be hoses, one hose ( sorry don't know which one) also contains one way valve that can slip sideways resulting in an any way valve.

              Ours has a slightly irregular idle when cold, starts, revs slowly rise to 1300 /1500 rpm and over about 15 seconds subside, but generally only on start up from cold.

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              • Monkeymagic
                S2Forum Possessed
                • Mar 2012
                • 3419
                • Country: England

                #8
                The 1.8t will throw fault codes in minutes if something is up. Monitor in mvb 15 for misfires on idle. Clean out throttle body and do an alignment in group 060 on vcds. The temp will almost certainly be the thermo as with all vag stats they fail open causing over cooling.

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