2009 A4 TSI

[Walter Moore]

You should use TOP TIER gasoline to prevent build up. Most major brands use
the top tier formulation.

As far as I know, the only reason to use premium fuel is if your
manufacturer recommends it - a sign that they have tuned the engine for
higher octane.


On Thu, Jun 5, 2014 at 10:26 AM, Vincent Gelinas <vrgelinas at gmail.com>
wrote:

> As far as I know, the energy content (BTU) is the same regardless of the
> grade of gasoline used.  The difference comes in the octane rating which
> measures the gasoline's resistance to ignition.  The reason premium is
> almost required for turbo engines is because the cylinder pressures
> generated by the forced induction increase the likelihood of pre-ignition,
> where the fuel ignites before the piston is in the power stroke.  This is
> also known as knocking and is very bad for the engine.  When knocking is
> detected, ignition timing is retarded (pulled) so the spark doesn't occur
> until later in the combustion cycle. This leads to more wasted fuel, poorer
> fuel economy, and less power because the gasoline doesn't have a chance to
> burn completely. When using good quality fuel, the ignition timing can be
> advanced a little, where the spark occurs sooner in the combustion cycle.
>  The fuel can then be burnt more completely, allowing for more power and
> increased fuel economy. Most modern engines are sensitive enough that they
> can detect a higher-octane fuel and adjust ignition timing accordingly.
>
> I may have this completely backwards.... feel free to correct me if I do.
>
> Vincent
>
>
> On Thu, Jun 5, 2014 at 10:05 AM, Jeremiah Curry <jeremiah at curryclan.net>
> wrote:
>
> > I had a 99 Passat and it started having a lot of trouble running.  Got to
> > the point where it would die at ide.  Took it to my Audi specialist and
> it
> > was full of carbon buildup.  He said it was from not running premium.
> >  Not sure if that was true, but they were very good and I never had any
> > trouble again after I started using premium.  I had always figured since
> it
> > was not a turbo I could just use regular and it would retard timing if
> > needed.
> >
> > -----Original Message----- From: Nick Lawrence
> > Sent: Thursday, June 5, 2014 7:50 AM
> > To: quattro at audifans.com
> > Subject: Re: 2009 A4 TSI
> >
> >
> > I also have trouble with this,   I would like to see a "real time"
> > timing display.    Does using regular instead of premium automatically
> > retard timing?  Or does the computer  have to sense knock then change
> > timing?      I personally haven't seen increased mpg using premium on my
> > cars. But I'm generally not on boost a lot.
> > Myth busters?
> > Nick
> >
> > On 6/5/2014 8:37 AM, Paul Caouette wrote:
> >
> >> OK!
> >>
> >> I can't help myself. Please look up the energy per unit volume of
> >> "premium" vs "regular" gas.
> >>
> >> I don't believe it is the fuel.  It is the way it is packed into the
> >> space where it is burned that increases the energy available. So, higher
> >> compression allows more fuel and oxygen to get pushed into the same
> volume
> >> awaiting that spark that lights it up. When a knock sensor detects a
> >> pre-ignituon. (Due to lower grade fuel) it regards the timing of the
> >> ignition. This will lead to less energy available in the flame front.
> But I
> >> don't think there is any more energy in premium gasoline. It is simply a
> >> better quality of the same stuff.
> >>
> >>
> >>
> >> Paul Caouette
> >> Sent from my iPhone
> >>
> >>
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-- 
+-----------------------------------------------------------------+
Walter R. Moore --  moorewr at gmail.com

"We would rather be ruined than changed;
We would rather die in our dread
Than climb the cross of the moment
And let our illusions die.”
             W.H. Auden