Mind the gap.....

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  • SHEEPISH-S2
    S2Forum Enthusiast
    • Sep 2003
    • 136
    • Country: United Kingdom

    #1

    Mind the gap.....

    Thought I'd throw up a post following a eurika moment today, and maybe this will help someone else....

    My 3B S2 had developed an annoying running issue in the last month or so that was progressively worsening, a missfire at high boost initially (juddering at 1.2 bar and not boosting any further), then making its way down to anything above 0.5 bar. To make matters worse it did not happen on my standard mapped ECU, but did on my remapped one, and neither ECU showed any fault codes.

    I was convinced it was boost related, but no leaks. I then started fearing that my piston rings were shot as it started blowing some oil out of the oil cap..... but a compression test with all cylinders at 10.5 to 11.5 bar alleviated that concern, and a new oil cap sorted the oil leak.

    Whilst compression testing I thought my spark plug gaps looked wide, so I revisited them today with feeler gauges in hand and found they all had gaps above 0.7mm, one having a gap larger than 0.85! I reset all the gaps to 0.55mm and hey presto she's running better than ever!

    Lessen learnt..... never overlook the supposedly simpler stuff! Unbelievable difference that it's made, both to the performance and my mood!
  • Ian Simmonds
    S2Forum Fiend
    • Jun 2005
    • 2858
    • Country: United Kingdom

    #2
    Totally off topic , but a certain Train Operator recently disciplined a Guard for announcing....

    "Please mind the gap between the timetable and reality" .... Reports suggest the train was in tears of laughter having listened to a total delay of 40 minutes worth of excuses...
    85 WR Urquattro, 85 20vT International liveried RallyRep
    93 MTMS2 Avant

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    • UrS4boy
      S2Forum Obsessed
      • Feb 2006
      • 11859
      • Country: Canada

      #3
      Originally posted by SHEEPISH-S2
      ..Whilst compression testing I thought my spark plug gaps looked wide, so I revisited them today with feeler gauges in hand and found they all had gaps above 0.7mm, one having a gap larger than 0.85! I reset all the gaps to 0.55mm and hey presto she's running better than ever! ...Lessen learnt..... never overlook the supposedly simpler stuff! Unbelievable difference that it's made, both to the performance and my mood!
      Sorry if the next bit is going to burst the bubble but be aware that some brand name plugs that we have been using are having problems dropping the ground/earth electrode, either breaking off or being eaten off. Depending on how you adjusted the gap, you might have stressed the weld where the electrode attaches to the threaded bit.

      Sorry.
      RS2'd 93 UrS4 5 spd sedan
      94 UrS4 V8 6 spd manual avant

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      • SHEEPISH-S2
        S2Forum Enthusiast
        • Sep 2003
        • 136
        • Country: United Kingdom

        #4
        No problem, good to know! Just pleased i found the root cause of the running problem.

        I was planning on ordering new plugs this week anyway as I noticed some hairline cracking in the ceramics, so probably past their best and due changing. Any particular brand to avoid, what brand do people recommend?

        Thanks.

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        • Error404
          Super Moderator
          • Mar 2007
          • 19789
          • Country: United Kingdom

          #5
          Yes avoid the OEM F5DPOR - engine killers these days. FWIW I was always told you should never re-gap a used plug
          Panthero Coupé quattro 20vt
          Indigo ABY coupé
          Imola B6 S4 Avant

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