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  1. #81
    RobinA3's Avatar
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    Quote Originally Posted by staz1000
    It has variable inlet timing ie the size of the inlet is adjusted. It's actually called Continuous intake camshaft adjustment. Variable Valve means it uses 4 inlet valves until a certain point and then all 8. Dependant on how many valves there are of course. The TFSI does not do this.

    EDIT: I'm reading the pdf file posted by a3norwich and although it mentions variable vale timing it doesn't seem to mention it again or explain it. If it was continously changing the number of vavles used then surely there'd be a kick like in any other VVT car. I'm still confused on this. Also as fsi injects direct;y into the chamber the inlet valves are only used to add air. And tumble flaps are used to adjust the fuel/air mixture inconjunction with the fuel pressure regulator. Normal VVT engines are completely different from this.

    VVT is where the rotation of the inlet camshaft is retarded or advanced to vary the opening of the inlet valves in relation to the crankshaft angle.

    VVT is not where the some of the valves are used and some not used, this is called cylinder deactivation!!!!! They use this on most gas guzzlers and also some city cars to increase fuel economy.
    Last edited by RobinA3; 4th June 2007 at 21:04.

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  3. #82
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    Also the tumble flaps are there to change 'tumble' or 'swirl' the inlet air flow to give a better combustion within the cylinders.

  4. #83
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  5. #84
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    Cylinder deactivation is where a bank of cylinders is deactivated not valves.

    It's called VVT (or VVTI) on renaults that vary the number of valves used. It's not just for fuel economy but for better emmissions and acceleration. 8 valves are better at lower revs and 16 at higher.

    But http://en.wikipedia.org/wiki/Variable_valve_timing says that VVT is when the lift, duration OR timing is changed. In the case of the TFSI it is not the timing that is changed which is what I thought everyone was trying to tell me. I've learned sopmething anyway.
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  6. #85
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    Quote Originally Posted by staz1000
    Cylinder deactivation is where a bank of cylinders is deactivated not valves.
    Thats also not exactly true!

    On V8 pushrod engines the valves are deactivated and fuel is not supplied to those cylinders.

  7. #86
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    I thought this post was about engine noise! Ok, the Tfsi may have VVT but that still does not make a clicking noise acceptable!

    I had a Toyota Celica for a few years and that definitely had VVT and I experienced nothing like the engine noise that suddenly appeared in the A3.

    Looking at all the posts (before it got to be a VVT hissy fit) there were a number of people who either did or did not have this noise.

    If it is normal, why does every tfsi engine not act this way and in my experience why does it suddenly happen?
    A5 2.0T Sport Brilliant Black

  8. #87
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    Quote Originally Posted by RobinA3
    Thats also not exactly true!

    On V8 pushrod engines the valves are deactivated and fuel is not supplied to those cylinders.
    You misunderstand me. I know if a bank of cylinders is deativated then the valves can also be deactivated. I meant it in terms of not all the valves deactivated on a cylinder that is still functioning.

    Smee noone is having a hissy fit. We're just discussing how the engine works.

    Also smee I'd give up worrying about it. Those with the noise put up with and and those without don't care about it until they get it themselves.
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  9. #88
    Geordie

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    Wilkinson

    Follow up to my post way back on march 16th about my engine noise. Sorry its a bit late but have been away. Audi were very good. Following my letter the Warranty Manager came to my house to listen to the noise from the belt region. He agreed it was a "fair shout". Car went in and it appears the belt was overtensioned. This was readjusted and the noise has all but gone.

  10. #89
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    Hi gents,

    I just bought a 07' S3 and i was also worried about the noise on tick over.
    Can't really hear it when cold (but engine is running faster) or once i take RPM up to 1,500 when hot.
    But when i put car in garage (when it's ticking over) sounds a 'little' like a diesel!
    Took it too my local audi garage and they said it is the injectors, i can't believe they are that loud!

  11. #90
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    Yep its the high pressure injectors, which i believe is diesel technology. I believe they improved this on the newer fsi engines
    Ron
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