S6 timing

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  • HMS-S6
    S2Forum Extremist
    • Jan 2010
    • 1164
    • Home: United Kingdom Current: England

    #211
    Yes mate, the garage I previously worked at checked them out then ultimately swapped them for set off my other good S6 and both cars remained exactly the same as before the swap. I'm currently trying to find out if it IS actually lean or the spark is poor. My understanding is that the AFR shows the same for both conditions?

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    • newsh
      S2Forum Obsessed
      • Aug 2003
      • 16226
      • Country: United Kingdom

      #212
      I know you've pressure tested but ... The small vac line which goes to the FPR from the inlet manifold, I think on the AAN there are 2 short pieces of cotton covered vac tube and a chrome plated hard line. If one of those 4 clips is a little loose and the rubber tube has gone a bit hard, then you can pressure test and get no leaks but go vacuum and it moves the pipe a bit and it leaks, next time you go on boost it may leak or it may not. I had this on the vac line to my ECU, the clip was done up tight but it leaked sometimes after lifting off and going back on boost. If the leak is in the line to the FPR then it will go lean on boost and occasionally rich on idle.

      I guess you're probably going to reply that the hose and the clips are all new! But it's worth a look just to see.

      When you pressure tested, did you finish up with soapy water and look for bubbles?

      S2 Coupe 3B Project


      Ur quattro restoration

      S2 Avant

      Boost is the new rock and roll!
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      • HMS-S6
        S2Forum Extremist
        • Jan 2010
        • 1164
        • Home: United Kingdom Current: England

        #213
        Originally posted by newsh
        I know you've pressure tested but ... The small vac line which goes to the FPR from the inlet manifold, I think on the AAN there are 2 short pieces of cotton covered vac tube and a chrome plated hard line. If one of those 4 clips is a little loose and the rubber tube has gone a bit hard, then you can pressure test and get no leaks but go vacuum and it moves the pipe a bit and it leaks, next time you go on boost it may leak or it may not. I had this on the vac line to my ECU, the clip was done up tight but it leaked sometimes after lifting off and going back on boost. If the leak is in the line to the FPR then it will go lean on boost and occasionally rich on idle.

        I guess you're probably going to reply that the hose and the clips are all new! But it's worth a look just to see.

        When you pressure tested, did you finish up with soapy water and look for bubbles?
        Yeh I'm really sorry but yeh they are all new too. Plus the fuel pressure is fine when it's running lean.

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        • newsh
          S2Forum Obsessed
          • Aug 2003
          • 16226
          • Country: United Kingdom

          #214
          Originally posted by HMS-S6
          Yeh I'm really sorry but yeh they are all new too. Plus the fuel pressure is fine when it's running lean.
          So at 1.5 Bar of boost you have 5.5 Bar fuel pressure? Just checking.

          S2 Coupe 3B Project


          Ur quattro restoration

          S2 Avant

          Boost is the new rock and roll!
          sigpic

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          • HMS-S6
            S2Forum Extremist
            • Jan 2010
            • 1164
            • Home: United Kingdom Current: England

            #215
            Well I'm back on stock map now but when I checked last year yes it was 5.4 at 1.4 bar. I can check this again Monday anyways though. Not afraid of double checking by now. Lol.

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            • HMS-S6
              S2Forum Extremist
              • Jan 2010
              • 1164
              • Home: United Kingdom Current: England

              #216
              Is there any way I can check its a Mixture OR Spark problem before I go looking the wrong direction?

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              • twoqu
                S2Forum Possessed
                • Sep 2003
                • 3103

                #217
                Have we discussed plugs?
                As you have said, I am not sure how you would determine whether its a lean mixture or misfiring.

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                • HMS-S6
                  S2Forum Extremist
                  • Jan 2010
                  • 1164
                  • Home: United Kingdom Current: England

                  #218
                  Yeh. It had new Bosch and as of Friday it now has new NGK. only thing I'd add is that the car certainly doesn't have a miss fire as such. I used to spot a misfire on a V12 engine a mile offso im sure I'd feel it on an I5. It's still smooth, just 'flat'

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                  • twoqu
                    S2Forum Possessed
                    • Sep 2003
                    • 3103

                    #219
                    Might be faulty logic but we are now looking at the very last components in the chain - injectors and spark plugs.
                    You seem to have enough fuel pressure/volume. The ecu controls the injectors by grounding them. They are fed effectively battery power with engine running. So that leaves just the actual injector!
                    By replacing all the coil gubbins with the coil conversion you are only left with the plugs!
                    If there are no boost leaks then they are the other parts of the combustion process other than the actual physical compression in the cylinder!

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                    • twoqu
                      S2Forum Possessed
                      • Sep 2003
                      • 3103

                      #220
                      But you are still getting @ 1 bar of boost?
                      Where are you teeing off for the gauge and does it tally with the in dash one?

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                      • twoqu
                        S2Forum Possessed
                        • Sep 2003
                        • 3103

                        #221
                        The NGK BKR-7EIX ? What have you gapped them at?

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                        • HMS-S6
                          S2Forum Extremist
                          • Jan 2010
                          • 1164
                          • Home: United Kingdom Current: England

                          #222
                          Originally posted by twoqu
                          Might be faulty logic but we are now looking at the very last components in the chain - injectors and spark plugs.
                          You seem to have enough fuel pressure/volume. The ecu controls the injectors by grounding them. They are fed effectively battery power with engine running. So that leaves just the actual injector!
                          By replacing all the coil gubbins with the coil conversion you are only left with the plugs!
                          If there are no boost leaks then they are the other parts of the combustion process other than the actual physical compression in the cylinder!
                          Hi, yes although a second new set of plugs went in on Friday and made no difference. I have also checked the injectors and swapped them from a good car. Also no difference at all.
                          I'm starting to wonder if some of these parts (coils) have the correct earth/feed.

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                          • HMS-S6
                            S2Forum Extremist
                            • Jan 2010
                            • 1164
                            • Home: United Kingdom Current: England

                            #223
                            Originally posted by twoqu
                            But you are still getting @ 1 bar of boost?
                            Where are you teeing off for the gauge and does it tally with the in dash one?
                            Yes it matches up perfectly.

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                            • HMS-S6
                              S2Forum Extremist
                              • Jan 2010
                              • 1164
                              • Home: United Kingdom Current: England

                              #224
                              Thing is with the plugs, I removed a NEW set of Bosh plugs, popped in the NGK's and literally no difference. Nor does it explain how it suddenly drops from 13.x AFR to high 14's.

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                              • HMS-S6
                                S2Forum Extremist
                                • Jan 2010
                                • 1164
                                • Home: United Kingdom Current: England

                                #225
                                Providing I rule out poor spark I have;

                                1: Fuel pressure
                                2: Boost reading at ECU
                                3: Throttle position
                                4: Air flow through MAF
                                5: Injectors

                                Is there any factor I have missed out regarding WOT mixture control or anything that isn't a factor!?

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